Aptamer-regulated colorimetric and electrochemical dual-mode sensor for the detection of uranyl ions utilizing AuNCs@COF composite

Aptamer-regulated colorimetric and electrochemical dual-mode sensor for the detection of uranyl ions utilizing AuNCs@COF composite | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Aptamer-regulated colorimetric and electrochemical dual-mode sensor for the detection of uranyl ions utilizing AuNCs@COF composite Zhijun Chen, Jinquan Liu, Wenyu Wang, Guoqing Qin, Siru Liu, Weilin Zhang, and 5 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-5971480/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 14 Apr, 2025 Read the published version in Microchimica Acta → Version 1 posted 14 You are reading this latest preprint version Abstract In this context, an innovative dual-mode colorimetric and electrochemical sensor was developed for the detection of uranyl ions (UO22+), utilizing a covalent organic framework@gold nanoclusters (AuNCs@COF) composite. The synthesis of AuNCs@COF was simple, and the incorporation of AuNCs imparted the composite with exceptional peroxidase-like catalytic activity and enhanced electrochemical properties. By regulating the adsorption and desorption of aptamers on the AuNCs@COF surface, both peroxidase-like activity and conductivity were modulated, enabling the detection of UO22+ utilizing colorimetric and electrochemical dual signals. Under optimal conditions, the sensor revealed a broad linear detection range and a low detection limit, with ranges of 1.36×10-10 - 1.36×10-5 mol/L for colorimetric detection and 5.0×10-10 - 2.5×10-5 mol/L for electrochemical detection, achieving detection limits of 107 pmol/L and 347 pmol/L, respectively. Unlike other single-mode sensor for UO22+ detection, this dual-mode sensor demonstrated superior sensitivity, specificity, and repeatability. Furthermore, the results of spiked recovery experiments in real water samples highlight the promising potential of this dual-mode sensor for environmental water monitoring applications. Uranyl Ion Gold nanoclusters Covalent organic frameworks Electrochemistry Colorimetry Figures Figure 1 Figure 2 Figure 3 Figure 4 1. Introduction Uranium plays an indispensable role in the military, atomic weaponry, and various other fields and generally stable in water in the form of uranyl ions (UO 2 2+ ) [1, 2] . Even if uranium levels in drinking water meet the safety standards, long-term consumption of water containing low concentrations of uranium can still lead to gradual accumulation in the body. This accumulation may result in chronic harm to organs including the kidneys, liver, and bones, while also increasing the risk of radiation-related diseases such as leukemia and cancer [3-5] . Establishing effective methods for detecting trace UO 2 2+ in water is of considerable importance for assessing uranium exposure, occupational health monitoring, and environmental impact evaluation. For the detection of UO 2 2+ , several methods have been developed, including fluorescence [6, 7] , electrochemical [8-10] , colorimetric [11-13] , atomic absorption spectrometry (AAS) [14] , atomic emission spectrometry (AES) [15] , surface-enhanced raman spectroscopy (SERS) [16, 17] and inductively coupled plasma mass spectrometry (ICP-MS) [18] . Among them, while technical methods like AAS and ICP-MS offer relatively high sensitivity, they often require expensive instruments, tedious and laborious sample pretreatment procedures, and extended analysis time. In contrast, electrochemical sensor presents advantages such as rapid analytical speed, high sensitivity, good selectivity and suitability for miniaturization [8, 19] . Colorimetric has emerged as one of the most frequently employed techniques for laboratory analysis and field determinations due to its outstanding visual analysis, cost-effectiveness, simplicity operation and convenient detection [12, 20] . Both electrochemical and colorimetric methods can achieve sensitive detection of UO 2 2+ in water, but most sensors used for UO 2 2+ detection operate in a single detection mode. This can sometimes be impacted by complex matrix interferences, resulting in false positives or false negatives, thereby compromising detection accuracy [21] . The creation of multimodal sensor platforms that integrate many output signals is suggested as a solution to this problem to enable highly reliable and convenient UO 2 2+ detection. Dual-mode sensor utilizes two distinct detection mechanisms, offers advantages such as high sensitivity, high selectivity, complementarity, and dual verification [22, 23] . Dual-mode sensor provides two independent detection results for the same sample, enabling cross-validation, which significantly enhances the reliability and accuracy of the results while minimizing the likelihood of false positives and false negatives [24-26] . Additionally, using two distinct detection methods minimizes potential errors associated with single-mode sensor, further improving precision. This dual-mode sensor strategy allows for accurate detection, even at low concentrations, making it a robust and versatile tool for sensitive analyses across various conditions. In recent years, dual-mode sensors have experienced rapid advancements and found applications in detecting UO 2 2+ . For instance, Sun et al. employed the Fe 3 O 4 -Au@CdTe nanomaterial to establish a dual-mode detection technique that combines fluorescence and surface-enhanced Raman scattering (SERS) [27] . This innovative approach showcased the remarkable sensitivity and accuracy of dual-mode sensors in UO 2 2+ detection. Despite these promising results, dual-mode sensor methods for UO 2 2+ remained relatively underexplored. This highlights a significant opportunity to develop more efficient and versatile dual-mode sensors for the accurate and sensitive detection of UO 2 2+ . Covalent organic frameworks (COFs) are a category of highly ordered porous materials that are constructed from light elements such as carbon (C), hydrogen (H), oxygen (O), and nitrogen (N), which are interconnected through covalent bonds. With tunable structures, chemical stability, and large specific surface areas, COFs show immense potential across various applications [28-30] . Compared to other porous materials, COFs offer abundant π-conjugation structures, a porous architecture, and highly customizable surface chemistry, making them excellent vehicle for loading functionalization factors or enriching target analytes. These features enhance sensitivity and selectivity in detection, enabling COFs to meet diverse sensing requirements and provide complementary detection mechanisms [31, 32] . This versatility has driven the development of COF-based dual-mode sensors for detecting organophosphorus pesticides (OPs), alkaline phosphatase (ALP) [33] , and other analytes. For example, Zhou et al. developed a homogeneous electrochemical and photothermal dual-mode sensing platform for thiocholine detection based on a COF/MB@MnO 2 composite [34] . Similarly, Lin et al. designed a fluorescent and electrochemical dual-mode technique for reliable detection of thiocholine using MB/COF@MnO 2 [35] . The above two methods were constructed using the MB/COF@MnO 2 composite, featuring high MB content, high oxidase activity of the MnO 2 layer, and specific thiocholine recognition. These features enhanced the platforms' sensitivity and selectivity for thiocholine detection. However, the self-assembly of MB and the encapsulation of MnO 2 nanosheets with nanozyme activity can be time-consuming and inefficient, which may affect the stability of the detection results. As far as we understand, there have been no reports of the usage of COFs for dual-mode sensor development aimed at UO 2 2+ detection. Therefore, it is of great significance to further modify COFs functionally, synthesize novel COF materials or COF-based composites, and enhance the performance of COFs. These advancements could enable the development of dual-mode detection for UO 2 2+ , thereby improving the accuracy and reliability of detection results. Inspired by the above investigation, a novel covalent organic framework@gold nanoclusters (AuNCs@COF) composite was fabricated using a facile assembly process. The AuNCs@COF composite demonstrated excellent peroxidase-like activity and enhanced electrochemical properties, thanks to the incorporation of AuNCs. Meanwhile, the colorimetric and electrochemical dual-mode sensors for UO 2 2+ detection were developed by integrating aptamers as recognition elements. The adsorption and desorption of aptamers on the AuNCs@COF surface regulated both the conductivity and peroxidase-like catalytic activity of the composite material, enabling sensitive detection of UO 2 2+ . This dual-mode detection system allows for cross-verification, thereby improving detection accuracy. Additionally, the proposed dual-mode sensor boasts simplicity in its design and construction while offering exceptional performance. 2. Experimental 2.1. Reagents and instruments Please refer to the supplementary material for further details. 2.2. Synthesis of COF COF was synthesized following a previously reported method [36] . First, 1,3,5-Tris(4-aminophenyl)benzene (TPB, 0.246 g, 0.7 mmol/L), 2,5-dimethoxyterephthalaldehyde (DMTP, 0.214 g, 1.1 mmol/L), and polyvinylpyrrolidone (PVP, 0.500 g) were dissolved in acetonitrile (250 mL). Then glacial acetic acid (12.5 mL) was introduced. Following two hours of stirring at 25 °C, benzaldehyde (10 μL, 0.1 mmol/L) was added, and stirring was maintained for an additional hour. Ultimately, centrifugation (10000 rpm, 20 min) produced a yellow precipitate, which was then rinsed three times with acetonitrile. The as-prepared yellow precipitate was vacuum-dried for 12 h at 40 °C. 2.3. Preparation of AuNCs@COF composite The synthesis of AuNCs@COF composite was mainly based on the previously documented method of preparing AuNCs with slight improvement [37] . 6-aza-2-thiothymine (ATT, 0.086 g), NaOH (0.060 g) and as-prepared COF (0.050 g) were ultrasonically dispersed with ultrapure water (7.5 mL). To ensure complete adsorption, the mixture was agitated at 25 °C for 12 h. Subsequently, HAuCl 4 ⋅3H 2 O (25 mmol/L, 2.5 mL) was added and left to stir for 6 h at 25 °C during the dark. After the reaction, centrifugation was used to gather the yellow solid product (10000 rpm, 20 min). To get rid of any remaining reactants or impurities, the product was rinsed three times using ultrapure water and ethanol alternately in turn. Finally, the AuNCs@COF composite was obtained by vacuum-drying the cleaned product for an entire night at 40 °C. 2.4. Dual-mode detection of UO 2 2+ For the colorimetric detection of UO 2 2+ , the AuNCs@COF was first dispersed in ultrapure water, so that the concentration reached 1.5 mg/mL. The UO 2 2+ aptamer (Apt) was then combined with the prepared AuNCs@COF solution and incubated for 60 minutes in an acetic acid-ammonium acetate buffer solution (200 mmol/L, pH 4.0) to allow for aptamer adsorption. Subsequently, varying concentrations of UO 2 2+ were introduced and reacted for an additional 60 min. After this incubation, hydrogen peroxide (H 2 O 2 , 100 mmol/L) and 3,3′,5,5′-tetramethylbenzidine (TMB, 20 mmol/L) were introduced to the solution for color development. After 30 minutes of reaction, a stopping solution was added to halt the process. The absorbance of the resulting solution at 652 nm was then measured. All reactions were performed at 25 °C to ensure consistency and reliability in the detection results. For the electrochemical detection of UO 2 2+ , the prepared AuNCs@COF solution was applied to the surface of a screen-printed carbon electrode (SPCE) and dried overnight at 25 °C, forming the AuNCs@COF-modified electrode (AuNCs@COF/SPCE). Subsequently, the UO 2 2+ aptamer was immobilized onto AuNCs@COF/SPCE by incubating the electrode in an acetate buffer solution (0.2 mol/L NaAc-HAc, pH 4.0) at 25 °C for 60 minutes. To remove unbound aptamer, the electrode was rinsed with the buffer, yielding the aptamer-modified electrode (Apt/AuNCs@COF/SPCE). Following aptamer modification, varying concentrations of UO 2 2+ were introduced onto Apt/AuNCs@COF/SPCE and incubated at 25 °C for 60 minutes to enable binding. Afterward, the electrodes were rinsed three times with NaAc-HAc buffer solution to eliminate unbound UO 2 2+ . Finally, the modified electrodes were immersed in a 0.1 mol/L KCl solution containing 5.0 mmol/L [Fe(CN) 6 ] 3-/4- , and the electrochemical signal were recorded using differential pulse voltammetry (DPV). 2.5. Peroxidase nanozyme catalytic kinetics To assess the catalytic activity of AuNCs@COF, the kinetic parameters of AuNCs@COF nano-enzymes mimicking peroxidase were determined by measuring the signal changes at different TMB and H 2 O 2 substrate concentrations according to the Lineweaver-Burk equation [38] . Simultaneously, the K m and v max values were calculated using the Lineweaver-Burk diagram transformed by the Michaelis-Menten equation. The Lineweaver-Burk diagram, derived from the Michaelis-Menten equation, was utilized to obtain the K m and v max values. In Eq, v 0 and [ S ] denoted the initial velocity and TMB/H 2 O 2 substrate concentration, respectively. v max represented the maximum reaction velocity. K m was referred to as the Michaelis constant. 2.6. Real water sample detection Two kinds of water samples, namely tap water and Xiangjiang water, were chosen for analysis. The samples underwent preparation through centrifugation, filtration using 0.22 μm filter paper, and dilution. Subsequently, varying concentrations of UO 2 2+ standard solution were added to determine the standard recovery rate. Tap water was collected within the laboratory, and Xiangjiang water was taken from Xiangjiang River. 3. Results and discussion 3.1. Principle of colorimetric/electrochemical dual-mode detection of UO 2 2+ A novel dual-mode sensor for the colorimetric and electrochemical detection of UO 2 2+ in water has been designed based on AuNCs@COF with aptamer as the regulatory and recognition unit. As illustrated in Scheme 1, The COF was firstly fabricated using a simple Schiff base condensation reaction. Subsequently, AuNPs were in situ modified on the surface of COFs to synthesize AuNCs@COFs with enhanced peroxidase-like activity and conductivity, attributed to the prevention of self-aggregation of the AuNCs [39] . In this system, the aptamer specifically recognizing UO 2 2+ can be adsorbed onto the AuNCs@COF surface through π-π conjugation. Consequently, both peroxidase-like activity and conductivity can be effectively modulated by dynamically regulating the adsorption and desorption of the aptamer on the AuNCs@COF surface, enabling the detection of UO 2 2+ through colorimetric and electrochemical dual signals. In the colorimetric detection mode, the peroxidase-like activity of AuNCs@COF was enhanced by the adsorption of the aptamer, which accelerated the conversion of H 2 O 2 to hydroxyl radicals (•OH). The generated •OH was then oxidized TMB into blue oxidized TMB (ox-TMB), producing a blue solution with a maximum absorption peak at 652 nm. Upon the addition of UO 2 2+ , specific binding occurred between UO 2 2+ and aptamer, causing aptamer to detach from the AuNCs@COF surface. This detachment reduced the peroxidase-like activity of AuNCs@COF, leading to a decrease in the absorption peak intensity at 652 nm. In the electrochemical detection mode, the aptamer adsorbed onto the AuNCs@COF surface, hindering electron transfer and reducing the surface current intensity of the electrode. This was due to the fact that both DNA and the redox probe [Fe(CN) 6 ] 3-/4- were negatively charged, which resulted in electrostatic repulsion. In the presence of UO 2 2+ , the specific binding of UO 2 2+ to aptamer caused aptamer to dissociate from AuNCs@COF/SPCE, enhancing the electrochemical signal. As a result, the specific detection of UO 2 2+ was achieved through the attenuation of colorimetric signals and the enhancement of electrochemical signals. Furthermore, by combining both colorimetric and electrochemical signals, this dual-mode sensor enabled accurate and sensitive detection of UO 2 2+ , making it a robust and versatile tool under various conditions. 3.2. Characterization of AuNCs@COF composite The morphology of the synthesized materials was characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM), with the results presented in Fig. 1. The synthesized COF exhibited radial spheres with an average particle size of 144 nm (Fig. 1A and 1C). As anticipated, the shape and size of COF modified with AuNCs remained largely unchanged following the modification process (Fig. 1B and 1D). This indicated that COF demonstrated considerable stability under these reaction conditions. As illustrated in Fig. 1E, the EDS spectra of AuNCs@COF corroborated the coexistence of C, N, O, and Au elements, indicating the successful modification of AuNCs onto the COF structure. The presence and uniform distribution of AuNCs throughout the COF framework were also confirmed through energy dispersive spectroscopy (EDS). Meanwhile, N 2 adsorption-desorption isotherms were employed for assessing the porosity of COF and AuNCs@COF. The pore size distributions for both COF and AuNCs@COF were found to be quite similar, with an average pore size of 3.5 nm, suggesting the presence of a substantial number of mesopores (Fig. 1G). Calculated from the Brunauer-Emmett-Teller (BET) equation, the BET specific surface area (SBET) of COF was determined to be 703.77 m 2 g -1 , while that of AuNCs@COF was measured at 339.39 m 2 g -1 . The SBET of AuNCs@COF was markedly lower than that of pristine COF, indicating that the successful modification with AuNCs occurred within the pores of COF rather than on its surface (Fig. 1F). The high dispersion of AuNCs within the COF matrix effectively avoided aggregation, thereby providing abundant active sites for catalytic reactions. The obtained COF was analyzed in comparison to the Fourier transform infrared (FT-IR) spectra of TPB and DMTP to further confirm the synthesis of COF. As shown in Fig. S1A, during the formation of COF, the -N-H vibration peak at 3355 cm -1 from TPB, along with the -C-H peaks at 2872 cm -1 and 2766 cm -1 , and the -C=O peak at 1687 cm -1 associated with the aldehyde group of DMTP, disappeared. Meanwhile, a new -C=N peak appeared at 1595 cm -1 , confirming the formation of COF. These spectral changes indicated that the condensation reaction between TPB and DMTP was successful, confirming the synthesis of COF. The chemical structures of the resulting composites were also characterized by FT-IR, as shown in Fig. 2A. Characteristic vibrational peaks of imine (-C=N) at 1617 cm -1 and 1595 cm -1 were observed for both COF and AuNCs@COF [36] . The high consistency of their FT-IR spectra suggested that the structural integrity of COF was unaffected by the doping of AuNCs. The crystallographic properties of COF and AuNCs@COF were also analyzed using X-ray diffraction (XRD) measurements. As shown in Fig. 2B, the COF exhibited diffraction peaks at 2.83°, 4.88°, 5.66°, and 7.49°, which corresponded to (100), (110), (200), and (210) crystallographic planes, respectively [40] . A similar diffraction pattern was observed in AuNCs@COF, indicating that the crystal structure integrity of the COF was preserved during the modification process. Nevertheless, their concentration in COF was relatively low, and FT-IR and XRD patterns do not showed the distinctive peaks associated with AuNCs. Utilizing X-ray photoelectron spectroscopy (XPS), the elemental compositions, chemical states, and molecular structures of COF, AuNCs, and AuNCs@COF surfaces were analyzed. As demonstrated in Fig. 2C, both COF and AuNCs@COF exhibited the presence of C, N, and O elements. Notably, AuNCs@COF also contained Au elements originating from AuNCs. In the spectrum of N 1s XPS (Fig. S1B), the two peaks centered at 399 eV and 400.1 eV belonged to -C=N and -N-H 2 , respectivelyc [41] . The -C=N peak corroborated the efficient synthesis of COF via a Schiff base condensation reaction. Furthermore, Au 4f 5/2 and Au 4f 7/2 were represented by characteristic peaks in the Au 4f XPS spectra at 88.2 eV and 84.4 eV, (Fig. S1C) [25] . Compared to the Au 4f 5/2 and Au 4f 7/2 peaks of pure AuNCs at 88.0 eV and 84.3 eV, no significant shift in their positions was observed (Fig. S1D). These results provided additional confirmation of the successful fabrication of the AuNCs@COF composites. 3.3. Feasibility investigation The operability of the proposed dual-mode method for UO 2 2+ detection was verified. In the colorimetric mode (Fig. 3A), a significant increase in the ultraviolet-visible absorption (UV-Vis) peak intensity at 652 nm was observed upon the introduction of aptamer alone. This confirmed that the aptamer adsorbed onto the surface of AuNCs@COF, enhancing the peroxidase-like activity of AuNCs@COF. The addition of varying concentrations of UO 2 2+ led to a noticeable reduction in the UV absorption signals at 652 nm, with a more pronounced decrease observed at higher concentrations of UO 2 2+ . These results suggested that UO 2 2+ specifically bound to aptamer [11] , causing its detachment from the surface of AuNCs@COF and thereby reducing the catalytic activity of the material. In the electrochemical mode (Fig. 3B), the introduction of aptamer dramatically lowered the electrical signal (curve a), demonstrating that aptamer effectively impeded electron transport, which resulted in a reduced current intensity at the electrode surface. When UO 2 2+ was present, there was a tendency for the electrochemical signal to be enhanced with increasing UO 2 2+ concentration (curves b and c). This confirmed that UO 2 2+ specifically bound to aptamer, promoting its dissociation from AuNCs@COF/SPCE, and restoring the electrochemical signal. These findings validated the proposed dual-mode sensor method for UO 2 2+ detection. 3.4. Electrochemical properties of AuNCs@COF The electrochemical properties of electrodes modified with different materials were assessed through cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). First, CV tests were performed in the 5.0 mmol/L [Fe(CN) 6 ] 3-/4- solution containing 0.1 mol/L KCl at a scan rate of 50 mV⋅s -1 , covering a scan potential range from -0.5 V to 0.6 V. As presented in Fig. 3C, the bare electrode's CV curve exhibited two pronounced and opposite redox peaks. The anodic and cathodic peak currents were -56.3 μA and 65.6 μA, respectively, indicating that the electrode works well and can be used for subsequent experimental studies. Upon modifying the electrode with COF, a slight decrease in peak currents was observed. The anodic peak current (Ipa) decreased to -51.0 μA, while the cathodic peak current (Ipc) dropped to 58.1 μA. This confirms the successful immobilization of the COF material on the electrode surface, likely due to its poor conductivity as an organic material, which hindered efficient electron transfer [42] . In contrast, AuNCs@COF/SPCE exhibited a significant increase compared to COF/SPCE, with the Ipa and Ipc rising to -57.4 μA and 63.9 μA, respectively. This enhancement was attributed to the superior electrical conductivity of AuNCs, which accelerated the rate of electron transfer. Following UO 2 2+ aptamer modification, Apt/AuNCs@COF/SPCE displayed a significant decrease in peak currents, with Ipa and Ipc dropping to -41.0 μA and 49.2 μA, respectively. The decrease in conductivity was credited to the electrostatic repulsion between the negatively charged aptamer and the [Fe(CN) 6 ] 3-/4- probes in the electrolyte solution [42, 43] , suggesting that the aptamer was adsorbed onto the AuNCs@COF surface. EIS techniques were also used for further assessment of the performance of the various electrodes. The Randle equivalent circuit corresponding to the EIS spectrum was also presented, comprising four elements: charge-transfer resistance (Rct), solution resistance (Rs), Warburg constant (W), and constant phase angle element (CPE). As showed in Fig. 3D, AuNCs@COF behaved the smallest semicircle diameter (1102.2 Ω), which was lower than that of the bare SPCE (1311.8 Ω), COF/SPCE (2021.3 Ω), and Apt/AuNCs@COF/SPCE (4588.3 Ω). The result further suggested that the incorporation of AuNCs effectively enhanced the conductivity of the electrodes, thereby improving the electrochemical performance. In conclusion, AuNCs@COF demonstrated outstanding electrochemical properties and served as a promising nanomaterial for applications in electrochemical sensing. 3.5. Peroxidase-like activity and catalytic mechanism of AuNCs@COF The peroxidase-like activity of the AuNCs@COF composite was determined by the TMB-H 2 O 2 system in a NaAc-HAc buffered environment. As exhibited in Fig. S2A, only a weak absorption peak at 652 nm was observed in the substrate-only condition, mainly attributed to the auto-oxidative decomposition of H 2 O 2 [44] . After the introduction of COF, oxTMB showed a slight elevation of the absorption peak at 652 nm, possibly because COF possesses some peroxidase-like activity. Moreover, With the introduction of AuNCs, the UV absorption peak of oxTMB at 652 nm demonstrated a notable elevation imputed to the peroxidase-like activity of AuNCs [39] . When the prepared AuNCs@COF was introduced, as predicted, a significantly enhanced UV absorption peak was observed compared to AuNCs alone, indicating a strong peroxidase-like activity of AuNCs@COF. The Michaelis-Menten equation was implemented to perform a steady-state kinetic analysis of AuNCs@COF's catalytic activity (Fig. S3A and S3B). Typical Lineweaver-Burk double reciprocal plots were generated to ascertain the K m and v max of AuNCs@COF nanozyme (Fig. S3C and S3D), and the decreased K m indicated a stronger affinity of the enzyme for the substrate. As presented in Table S1, the calculated K m and v max were 1.18 mM and 3.04×10 -4 mM s -1 for TMB, and 0.0821 mM and 0.988×10 -5 mM s -1 for H 2 O 2 , respectively. These values were compared with those of other peroxide-like nanoenzymes. The results indicated that AuNCs@COF demonstrated favorable peroxidase-like activity, with catalytic performance that is comparable to or superior to that of the referenced nanoenzymes. The excellent enzyme-like activity exhibited by AuNCs@COF can be attributed primarily to the high specific surface area of the COF structure. This characteristic facilitates the uniform dispersion of AuNCs, exposing more active sites. Consequently, substrate molecules will have more opportunities to accumulate on the porous COF via non-covalent interactions, which enhances the contact between the substrate and the catalyst, ultimately improving catalytic efficiency. To further explained the catalytic activity mechanism of AuNCs@COF, the generation of reactive oxygen species (ROS) generated during the oxidation reaction was initially confirmed through free radical scavenging experiments. Tryptophan (Trp) was utilized as 1 O 2 trapping agent, p-benzoquinone (PBQ) as •O 2 - trapping agent, and isopropyl alcohol (IPA) as •OH trapping agent, respectively. As depicted in Fig. S2B, the absorbance decreased following treatment with each of the three scavengers, with the most significant change observed after IPA treatment. This suggests that •OH was the dominant substance in the catalytic process of AuNCs@COF nanoenzymes. Electron paramagnetic resonance (EPR) experiments also verified this result. As revealed in Fig. S2C, the EPR spectrum displayed characteristic signal peaks corresponding to three radicals captured by 2,2,6,6-tetramethylpiperidine (TEMP) and 5,5-dimethyl-1-pyrrolin N-oxide (DMPO). Notably, the signal peak intensity of the •OH radical dramatically exceeded that of the other radicals, indicating a higher generation of •OH during the catalytic process, substantiating that •OH was the main active substance. According to previous studies [45] , AuNCs has exceptional electron transfer ability for H 2 O 2 . In conjunction with the previously mentioned experimental studies, the activity mechanism of the prepared AuNCs@COF was inferred. TMB and H 2 O 2 molecules were adsorbed onto the surface of AuNCs@COF composite, and TMB contributed lone pair electrons, while H 2 O 2 underwent oxidation to form •OH radicals as electrons were transferred through the activation site on AuNCs@COF. Subsequently, the •OH radicals catalyzed the oxidation of TMB to oxTMB. 3.6. Dual-mode detection of UO 2 2+ Under optimal conditions (Fig. S4 and Fig. S5), the constructed dual-mode sensor was employed to detect different concentrations of UO 2 2+ . As shown in Fig. 4A, the absorbance at 652 nm gradually decreased with increasing UO 2 2+ concentration in colorimetric mode. Meanwhile, as illustrated in Fig. 4B, there existed a strong linear correlation between the logarithm of UO 2 2+ concentration and absorbance within the concentration range of 1.36×10 -10 mol/L to 1.36×10 -5 mol/L. The calibration curve has a strong correlation coefficient (R 2 ) of 0.9981 and may be expressed as follows: y = 0.0666 lgC UO 2 2+ + 0.6087. The limit of detection (LOD) was found to be as low as 107 pmol/L using the probabilistic methods recommended by the International Union of Pure and Applied Chemistry (IUPAC). As depicted in Fig. 4C, the electrochemical signal in the electrochemical mode showed an increasing trend with the increase in UO 2 2+ concentration. In addition, Fig. 4D showed a good linear correlation between the electrochemical signal and the logarithm of the UO 2 2+ concentration over the concentration range of 5.0×10 -10 mol/L to 2.5×10 -5 mol/L. The calibration curve equation was y = 2.318 lgC UO 2 2+ + 12.918 with an R 2 of 0.9919 and an LOD of 347 pmol/L. Compared with other UO 2 2+ detection methods, the dual-mode method we developed has a lower detection limit and a wider linear range, showing excellent sensitivity, and can be used for the detection of lower concentrations of UO 2 2+ (Table S2). 3.7. Selectivity, reproducibility, and stability of dual-model method To evaluate the selectivity of dual-mode sensor, the effect of 50-fold concentration of 17 potential interfering metal ions (K + , Na + , Ag + , Ba 2+ , Cd 2+ , Co 2+ , Hg 2+ , Zn 2+ , Mg 2+ , Pb 2+ , Cu 2+ , Mn 2+ , Ca 2+ , Nd 3+ , La 3+ , Fe 3+ , V 5+ ) on the quantitative detection of UO 2 2+ was investigated. As shown in Fig. S6A and S6B, the signals remained largely unchanged in the presence of interfering ions, whether alone or in combination. In contrast, both colorimetric and electrochemical signals demonstrated a marked response following the introduction of UO 2 2+ . These results confirmed that the developed dual-mode sensor possesses excellent selectivity for UO₂²⁺ detection. To evaluate the reproducibility of the system, 11 different dual-mode sensors were tested in parallel. The relative standard deviation (RSD) for the colorimetric and electrochemical modes was determined to be 2.53% and 1.98%, respectively (Fig. S7A and S7B), confirming the sensor's excellent reproducibility. Furthermore, the stability of the electrochemical sensor was evaluated by measuring its response signals at multiple time points (1 day, 2 days, 5 days, 8 days, 9 days, 10 days, and 15 days) while maintaining consistent experimental conditions. The results showed that the current signal retained 89.70% of its initial value even after 15 days (Fig. S7C), demonstrating the sensor's satisfactory stability. 3.8. Analysis of UO 2 2+ in water samples To assess the practical detection performance of the developed colorimetric and electrochemical dual-mode sensor, a standard addition assay was performed to analyze varying concentrations of UO 2 2+ in tap water and Xiangjiang River samples. The findings of the experiment were presented in Table 1. The colorimetric sensor demonstrated recovery rates between 97.46% and 101.01% in tap water, and between 92.25% and 104.52% in Xiangjiang River water, accompanied by RSD values ranging from 1.98% to 8.93%. Similarly, the electrochemical sensor demonstrated average recoveries of 94.02% to 101.37% and 95.14% to 102.81% in tap water and Xiangjiang River water samples, respectively, with RSD values between 1.71% and 6.01%. The RSD values of the dual-mode sensor were consistently below 8.93%, confirming the reliability of the detection results. In summary, the dual-mode method was suitable for detecting UO 2 2+ in real environmental samples. Table 1 Results for the determination of UO 2 2+ in real samples. Sample Colorimetric method Electrochemical method Added (M) Found (M) Recovery (%) RSD (n=3, %) Added (M) Found (M) Recovery (%) RSD (n=3, %) Tap water 1.36×10 -8 1.38×10 -8 101.01 5.32 5.00×10 -8 5.07×10 -8 101.37 2.93 1.36×10 -7 1.36×10 -7 100.04 4.04 5.00×10 -7 4.70×10 -7 94.02 1.71 6.82×10 -6 6.65×10 -6 97.46 8.93 1.00×10 -5 1.00×10 -5 99.97 5.71 XiangjiangRiver 1.36×10 -8 1.43×10 -8 104.52 3.95 5.00×10 -8 5.10×10 -8 102.04 4.00 1.36×10 -7 1.26×10 -7 92.25 2.01 5.00×10 -7 5.14×10 -7 102.81 1.73 6.82×10 -6 6.78×10 -6 99.48 1.98 1.00×10 -5 9.51×10 -6 95.14 6.01 4. Conclusion Herein, a novel colorimetric and electrochemical dual-mode sensor was established for the detection of UO 2 2+ by integrated the peroxidase-like catalytic activity and electrochemical properties of synthesized AuNCs@COF with an aptamer as the regulatory and recognition element. The dual-mode sensor constructed has a lower detection limit and can be mutually validated through the combination of colorimetric and electrochemical methods, improving the accuracy of detection. The colorimetric mode had a linear range of 1.36×10 -10 - 1.36×10 -5 mol/L with an LOD of 107 pmol/L, and the electrochemical mode had a linear range of 5.0×10 -10 - 2.5×10 -5 mol/L with an LOD of 347 pmol/L. This method exhibited good specificity, stability and repeatability, while better results were achieved in the application of testing actual water samples of tap water and Xiangjiang River water. As a result, we expected that this dual-mode sensor has the potential to detect and analyze different types of uranium-containing samples. Declarations CRediT authorship contribution statement Zhijun Chen: Writing - original draft, Formal analysis, Visualization, Data curation. Jinquan Liu: Writing - review & editing, Supervision, Conceptualization. Wenyu Wang: Methodology, Investigation. Guoqing Qin: Validation. Siru Liu: Validation. Weilin Zhang: Investigation. Changmin Peng: Investigation. Yan Tan: Resources. Zhongran Dai: Resources. Deshuai Zhen: Resources. Le Li: Resources, Project administration. Declaration of Competing Interest The authors declare no financial conflicts of interest. Funding This work was supported by the National Natural Science Foundation of China (No. 12175103 and 82304195), the Natural Science Foundation of Hunan Province (No. 2023JJ50127) and the Open Funding of State Environmental Protection Key Laboratory of Monitoring for Heavy Metal Pollutants (No. KLMHM202434). References F B Xiao, H Li, P Xie, J Liu, W F Du, L Li, S Y Yang, Z Y Wu. Colloidal templating of highly ordered porous amidoxime-functionalized hydrogel for intelligent treatment of uranium contaminated water [J]. Chem Eng J, 2022, 431(2): 134141. H R Nan, Y H Liu, W J Gong, H B Peng, Y Q Wang, Z B Zhang, X H Cao. 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A versatile label-free electrochemical biosensor for circulating tumor DNA based on dual enzyme assisted multiple amplification strategy [J]. Biosensors and Bioelectronics, 2018, 122: 224-30. F G Ge, Y J Sun, K Wang, G J Ma, F X Li, Q Bai, Y Liu, N Sui. Colorimetric/electrochemical dual mode detection ascorbic acid based Au@PdNi nanozyme [J]. Microchem J, 2024, 201: 110745. Y L He, N Li, W K Li, X X Zhang, X Zhang, Z X Liu, Q Y Liu. 5,10,15,20-tetrakis (4-carboxylphenyl) porphyrin functionalized NiCo2S4 yolk-shell nanospheres: Excellent peroxidase-like activity, catalytic mechanism and fast cascade colorimetric biosensor for cholesterol [J]. Sensor Actuat B-Chem, 2021, 326: 128850. Scheme 1 Scheme 1 is available in the Supplementary Files section. Additional Declarations No competing interests reported. Supplementary Files SupplementaryMaterial.docx Scheme1.tif Scheme 1. (A) The preparation of COF, AuNCs@COF, and Apt/AuNCs@COF. (B) Schematic diagram of the principle of colorimetric and electrochemical dual-mode sensor detection of UO 2 2+ . GraphicalAbstract.docx Cite Share Download PDF Status: Published Journal Publication published 14 Apr, 2025 Read the published version in Microchimica Acta → Version 1 posted Editorial decision: Revision requested 20 Feb, 2025 Reviews received at journal 17 Feb, 2025 Reviews received at journal 14 Feb, 2025 Reviewers agreed at journal 13 Feb, 2025 Reviewers agreed at journal 12 Feb, 2025 Reviewers agreed at journal 09 Feb, 2025 Reviewers agreed at journal 08 Feb, 2025 Reviews received at journal 07 Feb, 2025 Reviewers agreed at journal 07 Feb, 2025 Reviewers agreed at journal 07 Feb, 2025 Reviewers invited by journal 07 Feb, 2025 Editor assigned by journal 07 Feb, 2025 Submission checks completed at journal 07 Feb, 2025 First submitted to journal 06 Feb, 2025 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-5971480","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":413263491,"identity":"0e9ac03a-430d-41ce-bd00-1b04e653e393","order_by":0,"name":"Zhijun Chen","email":"","orcid":"","institution":"University of South China","correspondingAuthor":false,"prefix":"","firstName":"Zhijun","middleName":"","lastName":"Chen","suffix":""},{"id":413263492,"identity":"2a9f08c6-a63e-45ca-ba80-4eea41cc5176","order_by":1,"name":"Jinquan Liu","email":"","orcid":"","institution":"University of South China","correspondingAuthor":false,"prefix":"","firstName":"Jinquan","middleName":"","lastName":"Liu","suffix":""},{"id":413263493,"identity":"0ac1aa2e-51ea-4f1b-bac0-d2cc7d24d177","order_by":2,"name":"Wenyu Wang","email":"","orcid":"","institution":"University of South China","correspondingAuthor":false,"prefix":"","firstName":"Wenyu","middleName":"","lastName":"Wang","suffix":""},{"id":413263494,"identity":"51a0f03c-b640-4e8a-9525-4f6c739be52c","order_by":3,"name":"Guoqing Qin","email":"","orcid":"","institution":"University of South China","correspondingAuthor":false,"prefix":"","firstName":"Guoqing","middleName":"","lastName":"Qin","suffix":""},{"id":413263495,"identity":"66431c82-c681-457b-b03e-7a6273250e29","order_by":4,"name":"Siru Liu","email":"","orcid":"","institution":"University of South China","correspondingAuthor":false,"prefix":"","firstName":"Siru","middleName":"","lastName":"Liu","suffix":""},{"id":413263496,"identity":"ce7e06d4-8b0f-46a0-ba05-c66b46a8e21e","order_by":5,"name":"Weilin Zhang","email":"","orcid":"","institution":"University of South China","correspondingAuthor":false,"prefix":"","firstName":"Weilin","middleName":"","lastName":"Zhang","suffix":""},{"id":413263497,"identity":"01979868-b2fa-4bb7-a339-f95bdbed19e4","order_by":6,"name":"Changmin Peng","email":"","orcid":"","institution":"University of South China","correspondingAuthor":false,"prefix":"","firstName":"Changmin","middleName":"","lastName":"Peng","suffix":""},{"id":413263498,"identity":"cf669795-e057-490e-995b-fbd50b37c6c1","order_by":7,"name":"Yan Tan","email":"","orcid":"","institution":"University of South China","correspondingAuthor":false,"prefix":"","firstName":"Yan","middleName":"","lastName":"Tan","suffix":""},{"id":413263499,"identity":"1c5894ee-7086-43b7-9dd2-a06401bf674b","order_by":8,"name":"Zhongran Dai","email":"","orcid":"","institution":"University of South China","correspondingAuthor":false,"prefix":"","firstName":"Zhongran","middleName":"","lastName":"Dai","suffix":""},{"id":413263500,"identity":"bc5671b5-d6fa-45f4-bfc9-c2908b1253ca","order_by":9,"name":"Deshuai Zhen","email":"","orcid":"","institution":"University of South China","correspondingAuthor":false,"prefix":"","firstName":"Deshuai","middleName":"","lastName":"Zhen","suffix":""},{"id":413263501,"identity":"86f932fb-cd01-44c1-8b9b-852b72e6a319","order_by":10,"name":"Le Li","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAArklEQVRIiWNgGAWjYHACxgMJBQxybOzNB4jXcyDBgMGYj+dYAglaGAwYEudJ5CgQp9zg/OEHBx4Y2KS3MeQwMPyo2EaElhtpBkCHpeW2MZw9wNhz5jYxWnhAfjmc28bYl8DM2EaMlvNnQFr+p7Mx8xgQqeVADkjLgQQ2NmK1SEL8kmzYxsOWcJAov/CdP/zw4Y8KO3n5+Y8PPvhRQYQWFHCARPWjYBSMglEwCnABANN8PXAqZHBUAAAAAElFTkSuQmCC","orcid":"","institution":"University of South China","correspondingAuthor":true,"prefix":"","firstName":"Le","middleName":"","lastName":"Li","suffix":""}],"badges":[],"createdAt":"2025-02-06 08:38:09","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-5971480/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-5971480/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1007/s00604-025-07156-3","type":"published","date":"2025-04-14T15:57:10+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":75873841,"identity":"6da23254-22c5-479c-9ed4-1d4c7387c8da","added_by":"auto","created_at":"2025-02-10 07:24:07","extension":"jpg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":123161,"visible":true,"origin":"","legend":"\u003cp\u003eThe SEM images of (A) COF and (B) AuNCs@COF. The TEM images of (C) COF and (D) AuNCs@COF. (E) Dark-field TEM picture and elemental mapping images of AuNCs@COF. (F) N\u003csub\u003e2\u003c/sub\u003e adsorption-desorption isotherms and (G) pore size distribution of COF and AuNCs@COF.\u003c/p\u003e","description":"","filename":"Figure1.tif.jpg","url":"https://assets-eu.researchsquare.com/files/rs-5971480/v1/76b1f315b07947aad7d8867e.jpg"},{"id":75874523,"identity":"ae017ff7-f4bc-4804-8a6a-712e7f91a09d","added_by":"auto","created_at":"2025-02-10 07:32:11","extension":"jpg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":1949630,"visible":true,"origin":"","legend":"\u003cp\u003e(A) FT-IR spectra and (B) XRD patterns of COF and AuNCs@COF. (C) XPS survey spectra of COF and AuNCs@COF.\u003c/p\u003e","description":"","filename":"Figure2.tif.jpg","url":"https://assets-eu.researchsquare.com/files/rs-5971480/v1/1c945278830ae88699b6d78e.jpg"},{"id":75873847,"identity":"57dd0d09-18e7-4631-8644-9b979abc2cf8","added_by":"auto","created_at":"2025-02-10 07:24:08","extension":"jpg","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":3367593,"visible":true,"origin":"","legend":"\u003cp\u003e(A) Feasibility analysis of the colorimetric model. (B) Feasibility analysis of the electrochemical model: a. Apt/AuNCs@COF/SPCE, b. 100 nmol/L UO\u003csub\u003e2\u003c/sub\u003e\u003csup\u003e2+\u003c/sup\u003e/Apt/AuNCs@COF/SPCE, c. 500 nmol/L UO\u003csub\u003e2\u003c/sub\u003e\u003csup\u003e2+\u003c/sup\u003e/Apt/AuNCs@COF/SPCE, d. AuNCs@COF/SPCE. (C) CV and (D) EIS curves of modified electrodes.\u003c/p\u003e","description":"","filename":"Figure3.tif.jpg","url":"https://assets-eu.researchsquare.com/files/rs-5971480/v1/8d90226f31c0d650afbef3bb.jpg"},{"id":75873854,"identity":"8b2dc7dd-2b9b-4260-ada8-db7719b09a59","added_by":"auto","created_at":"2025-02-10 07:24:08","extension":"jpg","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":2533148,"visible":true,"origin":"","legend":"\u003cp\u003e(A) UV-Vis absorption spectra in different UO\u003csub\u003e2\u003c/sub\u003e\u003csup\u003e2+\u003c/sup\u003e concentrations. (B) Calibration curves between absorbance values and UO\u003csub\u003e2\u003c/sub\u003e\u003csup\u003e2+\u003c/sup\u003e concentrations (inset: the linear fit plot of absorbance values as a function of the logarithm of UO\u003csub\u003e2\u003c/sub\u003e\u003csup\u003e2+\u003c/sup\u003e concentration, where the error bars were standard deviations for n=3). (C) Differential pulse voltammetry (DPV) curves for different concentrations of UO\u003csub\u003e2\u003c/sub\u003e\u003csup\u003e2+\u003c/sup\u003e. (D) Correspondence between peak current and UO\u003csub\u003e2\u003c/sub\u003e\u003csup\u003e2+\u003c/sup\u003e concentration (inset: the linear fit plot of peak current as a function of the logarithm of UO\u003csub\u003e2\u003c/sub\u003e\u003csup\u003e2+\u003c/sup\u003e concentration, where the error bars were standard deviations for n=3).\u003c/p\u003e","description":"","filename":"Figure4.tif.jpg","url":"https://assets-eu.researchsquare.com/files/rs-5971480/v1/3616b462d85625a2fe0b295f.jpg"},{"id":81050917,"identity":"3ae654c9-d821-48eb-8a5f-dbf43d509cdc","added_by":"auto","created_at":"2025-04-21 16:06:43","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":8964274,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-5971480/v1/f7b4e553-92c3-4e55-881b-fb5beecc54c3.pdf"},{"id":75874521,"identity":"bbfef7c2-61a2-4232-a2b2-c7b9f9d7b92b","added_by":"auto","created_at":"2025-02-10 07:32:08","extension":"docx","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":3998260,"visible":true,"origin":"","legend":"","description":"","filename":"SupplementaryMaterial.docx","url":"https://assets-eu.researchsquare.com/files/rs-5971480/v1/7f84ed68676872f8e8d1dda1.docx"},{"id":75874517,"identity":"e649d158-0ed1-4003-aa8d-8062e5f64521","added_by":"auto","created_at":"2025-02-10 07:32:07","extension":"tif","order_by":2,"title":"","display":"","copyAsset":false,"role":"supplement","size":4510398,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eScheme 1. \u003c/strong\u003e(A) The preparation of COF, AuNCs@COF, and Apt/AuNCs@COF. (B) Schematic diagram of the principle of colorimetric and electrochemical dual-mode sensor detection of UO\u003csub\u003e2\u003c/sub\u003e\u003csup\u003e2+\u003c/sup\u003e.\u003c/p\u003e","description":"","filename":"Scheme1.tif","url":"https://assets-eu.researchsquare.com/files/rs-5971480/v1/08dc18761522d3187da31a39.tif"},{"id":75873886,"identity":"38693d7e-1bc1-423d-8645-b3aeb6191fb3","added_by":"auto","created_at":"2025-02-10 07:24:09","extension":"docx","order_by":3,"title":"","display":"","copyAsset":false,"role":"supplement","size":3597586,"visible":true,"origin":"","legend":"","description":"","filename":"GraphicalAbstract.docx","url":"https://assets-eu.researchsquare.com/files/rs-5971480/v1/593ff29809c3790863b27311.docx"}],"financialInterests":"No competing interests reported.","formattedTitle":"Aptamer-regulated colorimetric and electrochemical dual-mode sensor for the detection of uranyl ions utilizing AuNCs@COF composite","fulltext":[{"header":"1.\tIntroduction","content":"\u003cp\u003eUranium plays an indispensable role in the military, atomic weaponry, and various other fields and generally stable in water in the form of uranyl ions (UO\u003csub\u003e2\u003c/sub\u003e\u003csup\u003e2+\u003c/sup\u003e)\u003csup\u003e\u0026nbsp;[1, 2]\u003c/sup\u003e. Even if uranium levels in drinking water meet the safety standards, long-term consumption of water containing low concentrations of uranium can still lead to gradual accumulation in the body. This accumulation may result in chronic harm to organs including the kidneys, liver, and bones, while also increasing the risk of radiation-related diseases such as leukemia and cancer\u003csup\u003e\u0026nbsp;[3-5]\u003c/sup\u003e. Establishing effective methods for detecting trace UO\u003csub\u003e2\u003c/sub\u003e\u003csup\u003e2+\u003c/sup\u003e in water is of considerable importance for assessing uranium exposure, occupational health monitoring, and environmental impact evaluation.\u003c/p\u003e\n\u003cp\u003eFor the detection of UO\u003csub\u003e2\u003c/sub\u003e\u003csup\u003e2+\u003c/sup\u003e, several methods have been developed, including fluorescence\u003csup\u003e\u0026nbsp;[6, 7]\u003c/sup\u003e, electrochemical\u003csup\u003e\u0026nbsp;[8-10]\u003c/sup\u003e, colorimetric\u003csup\u003e\u0026nbsp;[11-13]\u003c/sup\u003e, atomic absorption spectrometry (AAS)\u003csup\u003e\u0026nbsp;[14]\u003c/sup\u003e, atomic emission spectrometry (AES)\u003csup\u003e\u0026nbsp;[15]\u003c/sup\u003e, surface-enhanced raman spectroscopy (SERS)\u003csup\u003e\u0026nbsp;[16, 17]\u003c/sup\u003e and inductively coupled plasma mass spectrometry (ICP-MS)\u003csup\u003e\u0026nbsp;[18]\u003c/sup\u003e. Among them, while technical methods like AAS and ICP-MS offer relatively high sensitivity, they often require expensive instruments, tedious and laborious sample pretreatment procedures, and extended analysis time. In contrast, electrochemical sensor presents advantages such as rapid analytical speed, high sensitivity, good selectivity and suitability for miniaturization\u003csup\u003e\u0026nbsp;[8, 19]\u003c/sup\u003e. Colorimetric has emerged as one of the most frequently employed techniques for laboratory analysis and field determinations due to its outstanding visual analysis, cost-effectiveness, simplicity operation and convenient detection\u003csup\u003e\u0026nbsp;[12, 20]\u003c/sup\u003e. Both electrochemical and colorimetric methods can achieve sensitive detection of UO\u003csub\u003e2\u003c/sub\u003e\u003csup\u003e2+\u003c/sup\u003e in water, but most sensors used for UO\u003csub\u003e2\u003c/sub\u003e\u003csup\u003e2+\u003c/sup\u003e detection operate in a single detection mode. This can sometimes be impacted by complex matrix interferences, resulting in false positives or false negatives, thereby compromising detection accuracy\u003csup\u003e\u0026nbsp;[21]\u003c/sup\u003e. The creation of multimodal sensor platforms that integrate many output signals is suggested as a solution to this problem to enable highly reliable and convenient UO\u003csub\u003e2\u003c/sub\u003e\u003csup\u003e2+\u003c/sup\u003e detection.\u003c/p\u003e\n\u003cp\u003eDual-mode sensor utilizes two distinct detection mechanisms, offers advantages such as high sensitivity, high selectivity, complementarity, and dual verification\u003csup\u003e\u0026nbsp;[22, 23]\u003c/sup\u003e. Dual-mode sensor provides two independent detection results for the same sample, enabling cross-validation, which significantly enhances the reliability and accuracy of the results while minimizing the likelihood of false positives and false negatives\u003csup\u003e\u0026nbsp;[24-26]\u003c/sup\u003e. Additionally, using two distinct detection methods minimizes potential errors associated with single-mode sensor, further improving precision. This dual-mode sensor strategy allows for\u0026nbsp;accurate detection, even at low concentrations, making it a robust and versatile tool for sensitive analyses across various conditions. In recent years, dual-mode sensors have experienced rapid advancements and found applications in detecting UO\u003csub\u003e2\u003c/sub\u003e\u003csup\u003e2+\u003c/sup\u003e. For instance, Sun et al. employed the Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e-Au@CdTe nanomaterial to establish a dual-mode detection technique that combines fluorescence and surface-enhanced Raman scattering (SERS)\u003csup\u003e\u0026nbsp;[27]\u003c/sup\u003e. This innovative approach showcased the remarkable sensitivity and accuracy of dual-mode sensors in UO\u003csub\u003e2\u003c/sub\u003e\u003csup\u003e2+\u003c/sup\u003e detection. Despite these promising results, dual-mode sensor methods for UO\u003csub\u003e2\u003c/sub\u003e\u003csup\u003e2+\u003c/sup\u003e remained relatively underexplored. This highlights a significant opportunity to develop more efficient and versatile dual-mode sensors for the accurate and sensitive detection of UO\u003csub\u003e2\u003c/sub\u003e\u003csup\u003e2+\u003c/sup\u003e.\u003c/p\u003e\n\u003cp\u003eCovalent organic frameworks (COFs) are a category of highly ordered porous materials that are constructed from light elements such as carbon (C), hydrogen (H), oxygen (O), and nitrogen (N), which are interconnected through covalent bonds. With tunable structures, chemical stability, and large specific surface areas, COFs show immense potential across various applications\u003csup\u003e\u0026nbsp;[28-30]\u003c/sup\u003e. Compared to other porous materials, COFs offer abundant \u0026pi;-conjugation structures, a porous architecture, and highly customizable surface chemistry, making them excellent vehicle for loading functionalization factors or enriching target analytes. These features enhance sensitivity and selectivity in detection, enabling COFs to meet diverse sensing requirements and provide complementary detection mechanisms\u003csup\u003e\u0026nbsp;[31, 32]\u003c/sup\u003e. This versatility has driven the development of COF-based dual-mode sensors for detecting organophosphorus pesticides (OPs), alkaline phosphatase (ALP)\u003csup\u003e\u0026nbsp;[33]\u003c/sup\u003e, and other analytes. For example, Zhou et al. developed a homogeneous electrochemical and photothermal dual-mode sensing platform for thiocholine detection based on a COF/MB@MnO\u003csub\u003e2\u003c/sub\u003e composite\u003csup\u003e\u0026nbsp;[34]\u003c/sup\u003e. Similarly, Lin et al. designed a fluorescent and electrochemical dual-mode technique for reliable detection of thiocholine using MB/COF@MnO\u003csub\u003e2\u003c/sub\u003e\u003csup\u003e\u0026nbsp;[35]\u003c/sup\u003e. The above two methods were constructed using the MB/COF@MnO\u003csub\u003e2\u003c/sub\u003e composite, featuring high MB content, high oxidase activity of the MnO\u003csub\u003e2\u003c/sub\u003e layer, and specific thiocholine recognition. These features enhanced the platforms\u0026apos; sensitivity and selectivity for thiocholine detection. However, the self-assembly of MB and the encapsulation of MnO\u003csub\u003e2\u003c/sub\u003e nanosheets with nanozyme activity can be time-consuming and inefficient, which may affect the stability of the detection results. As far as we understand, there have been no reports of the usage of COFs for dual-mode sensor development aimed at UO\u003csub\u003e2\u003c/sub\u003e\u003csup\u003e2+\u003c/sup\u003e detection. Therefore, it is of great significance to further modify COFs functionally, synthesize novel COF materials or COF-based composites, and enhance the performance of COFs. These advancements could enable the development of dual-mode detection for UO\u003csub\u003e2\u003c/sub\u003e\u003csup\u003e2+\u003c/sup\u003e, thereby improving the accuracy and reliability of detection results.\u003c/p\u003e\n\u003cp\u003eInspired by the above investigation, a novel covalent organic framework@gold nanoclusters (AuNCs@COF) composite was fabricated using a facile assembly process.\u0026nbsp;The AuNCs@COF composite demonstrated excellent peroxidase-like activity and enhanced electrochemical properties, thanks to the incorporation of AuNCs. Meanwhile, the colorimetric and electrochemical dual-mode sensors for UO\u003csub\u003e2\u003c/sub\u003e\u003csup\u003e2+\u003c/sup\u003e detection were developed by integrating aptamers as recognition elements. The adsorption and desorption of aptamers on the AuNCs@COF surface regulated both the conductivity and peroxidase-like catalytic activity of the composite material, enabling sensitive detection of UO\u003csub\u003e2\u003c/sub\u003e\u003csup\u003e2+\u003c/sup\u003e. This dual-mode detection system allows for cross-verification, thereby improving detection accuracy. Additionally, the proposed dual-mode sensor boasts simplicity in its design and construction while offering exceptional performance.\u003c/p\u003e"},{"header":"2.\tExperimental","content":"\u003cp\u003e\u003cstrong\u003e2.1.\u0026nbsp; \u0026nbsp;\u0026nbsp;Reagents and\u0026nbsp;\u003c/strong\u003e\u003cstrong\u003einstruments\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003ePlease refer to the supplementary material for further details.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e2.2.\u0026nbsp; \u0026nbsp;\u0026nbsp;Synthesis of\u0026nbsp;\u003c/strong\u003e\u003cstrong\u003eCOF\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eCOF was synthesized following a previously reported method\u003csup\u003e\u0026nbsp;[36]\u003c/sup\u003e. First, 1,3,5-Tris(4-aminophenyl)benzene (TPB, 0.246 g, 0.7 mmol/L), 2,5-dimethoxyterephthalaldehyde (DMTP, 0.214 g, 1.1 mmol/L), and polyvinylpyrrolidone (PVP, 0.500 g) were dissolved in acetonitrile (250 mL). Then glacial acetic acid (12.5 mL) was introduced. Following two hours of stirring at 25 \u0026deg;C, benzaldehyde (10 \u0026mu;L, 0.1 mmol/L) was added, and stirring was maintained for an additional hour. Ultimately, centrifugation (10000 rpm, 20 min) produced a yellow precipitate, which was then rinsed three times with acetonitrile. The as-prepared yellow precipitate was vacuum-dried for 12 h at 40 \u0026deg;C.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e2.3.\u0026nbsp; \u0026nbsp;\u0026nbsp;Preparation of AuNCs@COF\u0026nbsp;\u003c/strong\u003e\u003cstrong\u003ecomposite\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe synthesis of AuNCs@COF composite was mainly based on the previously documented method of preparing AuNCs with slight improvement\u003csup\u003e\u0026nbsp;[37]\u003c/sup\u003e. 6-aza-2-thiothymine (ATT, 0.086 g), NaOH (0.060 g) and as-prepared COF (0.050 g) were ultrasonically dispersed with ultrapure water (7.5 mL). To ensure complete adsorption, the mixture was agitated at 25 \u0026deg;C for 12 h. Subsequently, HAuCl\u003csub\u003e4\u003c/sub\u003e\u0026sdot;3H\u003csub\u003e2\u003c/sub\u003eO (25 mmol/L, 2.5 mL) was added and left to stir for 6 h at 25 \u0026deg;C during the dark. After the reaction, centrifugation was used to gather the yellow solid product (10000 rpm, 20 min). To get rid of any remaining reactants or impurities, the product was rinsed three times using ultrapure water and ethanol alternately in turn. Finally, the AuNCs@COF composite was obtained by vacuum-drying the cleaned product for an entire night at 40 \u0026deg;C.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e2.4.\u0026nbsp; \u0026nbsp;\u0026nbsp;Dual-mode detection of UO\u003csub\u003e2\u003c/sub\u003e\u003csup\u003e2+\u003c/sup\u003e\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eFor the colorimetric detection of UO\u003csub\u003e2\u003c/sub\u003e\u003csup\u003e2+\u003c/sup\u003e, the AuNCs@COF was first dispersed in ultrapure water, so that the concentration reached 1.5 mg/mL. The UO\u003csub\u003e2\u003c/sub\u003e\u003csup\u003e2+\u003c/sup\u003e aptamer (Apt) was then combined with the prepared AuNCs@COF solution and incubated for 60 minutes in an acetic acid-ammonium acetate buffer solution (200 mmol/L, pH 4.0) to allow for aptamer adsorption. Subsequently, varying concentrations of UO\u003csub\u003e2\u003c/sub\u003e\u003csup\u003e2+\u003c/sup\u003e were introduced and reacted for an additional 60 min. After this incubation, hydrogen peroxide (H\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e2\u003c/sub\u003e, 100 mmol/L) and 3,3\u0026prime;,5,5\u0026prime;-tetramethylbenzidine (TMB, 20 mmol/L) were introduced to the solution for color development. After 30 minutes of reaction, a stopping solution was added to halt the process. The absorbance of the resulting solution at 652 nm was then measured. All reactions were performed at 25 \u0026deg;C to ensure consistency and reliability in the detection results.\u003c/p\u003e\n\u003cp\u003eFor the electrochemical detection of UO\u003csub\u003e2\u003c/sub\u003e\u003csup\u003e2+\u003c/sup\u003e, the prepared AuNCs@COF solution was applied to the surface of a screen-printed carbon electrode (SPCE) and dried overnight at 25 \u0026deg;C, forming the AuNCs@COF-modified electrode (AuNCs@COF/SPCE). Subsequently, the UO\u003csub\u003e2\u003c/sub\u003e\u003csup\u003e2+\u003c/sup\u003e aptamer was immobilized onto AuNCs@COF/SPCE by incubating the electrode in an acetate buffer solution (0.2 mol/L NaAc-HAc, pH 4.0) at 25 \u0026deg;C for 60 minutes. To remove unbound aptamer, the electrode was rinsed with the buffer, yielding the aptamer-modified electrode (Apt/AuNCs@COF/SPCE). Following aptamer modification, varying concentrations of UO\u003csub\u003e2\u003c/sub\u003e\u003csup\u003e2+\u003c/sup\u003e were introduced onto Apt/AuNCs@COF/SPCE and incubated at 25 \u0026deg;C for 60 minutes to enable binding. Afterward, the electrodes were rinsed three times with NaAc-HAc buffer solution to eliminate unbound UO\u003csub\u003e2\u003c/sub\u003e\u003csup\u003e2+\u003c/sup\u003e. Finally, the modified electrodes were immersed in a 0.1 mol/L KCl solution containing 5.0 mmol/L [Fe(CN)\u003csub\u003e6\u003c/sub\u003e]\u003csup\u003e3-/4-\u003c/sup\u003e, and the electrochemical signal were recorded using differential pulse voltammetry (DPV).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e2.5.\u0026nbsp; \u0026nbsp;\u0026nbsp;Peroxidase nanozyme catalytic kinetics\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eTo assess the catalytic activity of AuNCs@COF, the kinetic parameters of AuNCs@COF nano-enzymes mimicking peroxidase were determined by measuring the signal changes at different TMB and H\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e2\u003c/sub\u003e substrate concentrations according to the Lineweaver-Burk equation\u003csup\u003e\u0026nbsp;[38]\u003c/sup\u003e. Simultaneously, the \u003cem\u003eK\u003csub\u003em\u003c/sub\u003e\u003c/em\u003e and \u003cem\u003ev\u003csub\u003emax\u003c/sub\u003e\u003c/em\u003e values were calculated using the Lineweaver-Burk diagram transformed by the Michaelis-Menten equation. The Lineweaver-Burk diagram, derived from the Michaelis-Menten equation, was utilized to obtain the \u003cem\u003eK\u003csub\u003em\u003c/sub\u003e\u003c/em\u003e and \u003cem\u003ev\u003csub\u003emax\u003c/sub\u003e\u003c/em\u003e values.\u003c/p\u003e\n\u003cp\u003e\u003cimg src=\"data:image/png;base64,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\" width=\"133\" height=\"46\"\u003e\u003c/p\u003e\n\u003cp\u003eIn Eq, \u003cem\u003ev\u003csub\u003e0\u003c/sub\u003e\u003c/em\u003e and [\u003cem\u003eS\u003c/em\u003e] denoted the initial velocity and TMB/H\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e2\u003c/sub\u003e substrate concentration, respectively. \u003cem\u003ev\u003csub\u003emax\u003c/sub\u003e\u003c/em\u003e represented the maximum reaction velocity. \u003cem\u003eK\u003csub\u003em\u003c/sub\u003e\u003c/em\u003e was referred to as the Michaelis constant.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e2.6.\u0026nbsp; \u0026nbsp;\u0026nbsp;Real water sample detection\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eTwo kinds of water samples, namely tap water and Xiangjiang water, were chosen for analysis. The samples underwent preparation through centrifugation, filtration using 0.22 \u0026mu;m filter paper, and dilution. Subsequently, varying concentrations of UO\u003csub\u003e2\u003c/sub\u003e\u003csup\u003e2+\u003c/sup\u003e standard solution were added to determine the standard recovery rate. Tap water was collected within the laboratory, and Xiangjiang water was taken from Xiangjiang River.\u003c/p\u003e"},{"header":"3.\tResults and discussion","content":"\u003cp\u003e\u003cstrong\u003e3.1.\u0026nbsp; \u0026nbsp;\u0026nbsp;Principle of colorimetric/electrochemical dual-mode detection of UO\u003csub\u003e2\u003c/sub\u003e\u003csup\u003e2+\u003c/sup\u003e\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eA novel dual-mode sensor for the colorimetric and electrochemical detection of UO\u003csub\u003e2\u003c/sub\u003e\u003csup\u003e2+\u003c/sup\u003e in water has been designed based on AuNCs@COF with aptamer as the regulatory and recognition unit. As illustrated in Scheme 1, The COF was firstly fabricated using a simple Schiff base condensation reaction. Subsequently, AuNPs were in situ modified on the surface of COFs to synthesize AuNCs@COFs with enhanced peroxidase-like activity and conductivity, attributed to the prevention of self-aggregation of the AuNCs\u003csup\u003e\u0026nbsp;[39]\u003c/sup\u003e. In this system, the aptamer specifically recognizing UO\u003csub\u003e2\u003c/sub\u003e\u003csup\u003e2+\u003c/sup\u003e can be adsorbed onto the AuNCs@COF surface through \u0026pi;-\u0026pi; conjugation. Consequently, both peroxidase-like activity and conductivity can be effectively modulated by dynamically regulating the adsorption and desorption of the aptamer on the AuNCs@COF surface, enabling the detection of UO\u003csub\u003e2\u003c/sub\u003e\u003csup\u003e2+\u003c/sup\u003e through colorimetric and electrochemical dual signals. In the colorimetric detection mode, the peroxidase-like activity of AuNCs@COF was enhanced by the adsorption of the aptamer, which accelerated the conversion of H\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e2\u003c/sub\u003e to hydroxyl radicals (\u0026bull;OH). The generated \u0026bull;OH was then oxidized TMB into blue oxidized TMB (ox-TMB), producing a blue solution with a maximum absorption peak at 652 nm. Upon the addition of UO\u003csub\u003e2\u003c/sub\u003e\u003csup\u003e2+\u003c/sup\u003e, specific binding occurred between UO\u003csub\u003e2\u003c/sub\u003e\u003csup\u003e2+\u003c/sup\u003e and aptamer, causing aptamer to detach from the AuNCs@COF surface. This detachment reduced the peroxidase-like activity of AuNCs@COF, leading to a decrease in the absorption peak intensity at 652 nm. In the electrochemical detection mode, the aptamer adsorbed onto the AuNCs@COF surface, hindering electron transfer and reducing the surface current intensity of the electrode. This was due to the fact that both DNA and the redox probe [Fe(CN)\u003csub\u003e6\u003c/sub\u003e]\u003csup\u003e3-/4-\u003c/sup\u003e were negatively charged, which resulted in electrostatic repulsion. In the presence of UO\u003csub\u003e2\u003c/sub\u003e\u003csup\u003e2+\u003c/sup\u003e, the specific binding of UO\u003csub\u003e2\u003c/sub\u003e\u003csup\u003e2+\u003c/sup\u003e to aptamer caused aptamer to dissociate from AuNCs@COF/SPCE, enhancing the electrochemical signal. As a result, the specific detection of UO\u003csub\u003e2\u003c/sub\u003e\u003csup\u003e2+\u003c/sup\u003e was achieved through the attenuation of colorimetric signals and the enhancement of electrochemical signals. Furthermore, by combining both colorimetric and electrochemical signals, this dual-mode sensor enabled accurate and sensitive detection of UO\u003csub\u003e2\u003c/sub\u003e\u003csup\u003e2+\u003c/sup\u003e, making it a robust and versatile tool under various conditions.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e3.2.\u0026nbsp; \u0026nbsp;\u0026nbsp;Characterization of AuNCs@COF composite\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe morphology of the synthesized materials was characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM), with the results presented in Fig. 1. The synthesized COF exhibited radial spheres with an average particle size of 144 nm (Fig. 1A and 1C). As anticipated, the shape and size of COF modified with AuNCs remained largely unchanged following the modification process (Fig. 1B and 1D). This indicated that COF demonstrated considerable stability under these reaction conditions. As illustrated in Fig. 1E, the EDS spectra of AuNCs@COF corroborated the coexistence of C, N, O, and Au elements, indicating the successful modification of AuNCs onto the COF structure. The presence and uniform distribution of AuNCs throughout the COF framework were also confirmed through energy dispersive spectroscopy (EDS). Meanwhile, N\u003csub\u003e2\u003c/sub\u003e adsorption-desorption isotherms were employed for assessing the porosity of COF and AuNCs@COF. The pore size distributions for both COF and AuNCs@COF were found to be quite similar, with an average pore size of 3.5 nm, suggesting the presence of a substantial number of mesopores (Fig. 1G). Calculated from the Brunauer-Emmett-Teller (BET) equation, the BET specific surface area (SBET) of COF was determined to be 703.77 m\u003csup\u003e2\u003c/sup\u003e g\u003csup\u003e-1\u003c/sup\u003e, while that of AuNCs@COF was measured at 339.39 m\u003csup\u003e2\u003c/sup\u003e g\u003csup\u003e-1\u003c/sup\u003e. The SBET of AuNCs@COF was markedly lower than that of pristine COF, indicating that the successful modification with AuNCs occurred within the pores of COF rather than on its surface (Fig. 1F). The high dispersion of AuNCs within the COF matrix effectively avoided aggregation, thereby providing abundant active sites for catalytic reactions.\u003c/p\u003e\n\u003cp\u003eThe obtained COF was analyzed in comparison to the Fourier transform infrared (FT-IR) spectra of TPB and DMTP to further confirm the synthesis of COF. As shown in Fig. S1A, during the formation of COF, the -N-H vibration peak at 3355 cm\u003csup\u003e-1\u003c/sup\u003e\u003csup\u003e\u0026nbsp;\u003c/sup\u003efrom TPB, along with the -C-H peaks at 2872 cm\u003csup\u003e-1\u003c/sup\u003e and 2766 cm\u003csup\u003e-1\u003c/sup\u003e, and the -C=O peak at 1687 cm\u003csup\u003e-1\u003c/sup\u003e associated with the aldehyde group of DMTP, disappeared. Meanwhile, a new -C=N peak appeared at 1595 cm\u003csup\u003e-1\u003c/sup\u003e, confirming the formation of COF. These spectral changes indicated that the condensation reaction between TPB and DMTP was successful, confirming the synthesis of COF. The chemical structures of the resulting composites were also characterized by FT-IR, as shown in Fig. 2A. Characteristic vibrational peaks of imine (-C=N) at 1617 cm\u003csup\u003e-1\u003c/sup\u003e and 1595 cm\u003csup\u003e-1\u003c/sup\u003e were observed for both COF and AuNCs@COF\u003csup\u003e\u0026nbsp;[36]\u003c/sup\u003e. The high consistency of their FT-IR spectra suggested that the structural integrity of COF was unaffected by the doping of AuNCs.\u003c/p\u003e\n\u003cp\u003eThe crystallographic properties of COF and AuNCs@COF were also analyzed using X-ray diffraction (XRD) measurements. As shown in Fig. 2B, the COF exhibited diffraction peaks at 2.83\u0026deg;, 4.88\u0026deg;, 5.66\u0026deg;, and 7.49\u0026deg;, which corresponded to (100), (110), (200), and (210) crystallographic planes, respectively\u003csup\u003e\u0026nbsp;[40]\u003c/sup\u003e. A similar diffraction pattern was observed in AuNCs@COF, indicating that the crystal structure integrity of the COF was preserved during the modification process. Nevertheless, their concentration in COF was relatively low, and FT-IR and XRD patterns do not showed the distinctive peaks associated with AuNCs.\u003c/p\u003e\n\u003cp\u003eUtilizing X-ray photoelectron spectroscopy (XPS), the elemental compositions, chemical states, and molecular structures of COF, AuNCs, and AuNCs@COF surfaces were analyzed. As demonstrated in Fig. 2C, both COF and AuNCs@COF exhibited the presence of C, N, and O elements. Notably, AuNCs@COF also contained Au elements originating from AuNCs. In the spectrum of N 1s XPS (Fig. S1B), the two peaks centered at 399 eV and 400.1 eV belonged to -C=N and -N-H\u003csub\u003e2\u003c/sub\u003e, respectivelyc\u003csup\u003e\u0026nbsp;[41]\u003c/sup\u003e. The -C=N peak corroborated the efficient synthesis of COF via a Schiff base condensation reaction. Furthermore, Au 4f\u003csub\u003e5/2\u003c/sub\u003e and Au 4f\u003csub\u003e7/2\u003c/sub\u003ewere represented by characteristic peaks in the Au 4f XPS spectra at 88.2 eV and 84.4 eV, (Fig. S1C)\u003csup\u003e\u0026nbsp;[25]\u003c/sup\u003e. Compared to the Au 4f\u003csub\u003e5/2\u003c/sub\u003e and Au 4f\u003csub\u003e7/2\u003c/sub\u003e peaks of pure AuNCs at 88.0 eV and 84.3 eV, no significant shift in their positions was observed (Fig. S1D). These results provided additional confirmation of the successful fabrication of the AuNCs@COF composites.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e3.3.\u0026nbsp; \u0026nbsp;\u0026nbsp;Feasibility investigation\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe operability of the proposed dual-mode method for UO\u003csub\u003e2\u003c/sub\u003e\u003csup\u003e2+\u003c/sup\u003e detection was verified. In the colorimetric mode (Fig. 3A), a significant increase in the ultraviolet-visible absorption (UV-Vis) peak intensity at 652 nm was observed upon the introduction of aptamer alone. This confirmed that the aptamer adsorbed onto the surface of AuNCs@COF, enhancing the peroxidase-like activity of AuNCs@COF. The addition of varying concentrations of UO\u003csub\u003e2\u003c/sub\u003e\u003csup\u003e2+\u003c/sup\u003e led to a noticeable reduction in the UV absorption signals at 652 nm, with a more pronounced decrease observed at higher concentrations of UO\u003csub\u003e2\u003c/sub\u003e\u003csup\u003e2+\u003c/sup\u003e. These results suggested that UO\u003csub\u003e2\u003c/sub\u003e\u003csup\u003e2+\u003c/sup\u003e specifically bound to aptamer \u003csup\u003e[11]\u003c/sup\u003e, causing its detachment from the surface of AuNCs@COF and thereby reducing the catalytic activity of the material.\u003c/p\u003e\n\u003cp\u003eIn the electrochemical mode (Fig. 3B), the introduction of aptamer dramatically lowered the electrical signal (curve a), demonstrating that aptamer effectively impeded electron transport, which resulted in a reduced current intensity at the electrode surface. When UO\u003csub\u003e2\u003c/sub\u003e\u003csup\u003e2+\u003c/sup\u003e was present, there was a tendency for the electrochemical signal to be enhanced with increasing UO\u003csub\u003e2\u003c/sub\u003e\u003csup\u003e2+\u003c/sup\u003e concentration (curves b and c). This confirmed that UO\u003csub\u003e2\u003c/sub\u003e\u003csup\u003e2+\u003c/sup\u003e specifically bound to aptamer, promoting its dissociation from AuNCs@COF/SPCE, and restoring the electrochemical signal. These findings validated the proposed dual-mode sensor method for UO\u003csub\u003e2\u003c/sub\u003e\u003csup\u003e2+\u003c/sup\u003e detection.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e3.4.\u0026nbsp; \u0026nbsp;\u0026nbsp;Electrochemical properties of AuNCs@COF\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe electrochemical properties of electrodes modified with different materials were assessed through cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). First, CV tests were performed in the 5.0 mmol/L [Fe(CN)\u003csub\u003e6\u003c/sub\u003e]\u003csup\u003e3-/4-\u003c/sup\u003e solution containing 0.1 mol/L KCl at a scan rate of 50 mV\u0026sdot;s\u003csup\u003e-1\u003c/sup\u003e, covering a scan potential range from -0.5 V to 0.6 V. As presented in Fig. 3C, the bare electrode\u0026apos;s CV curve exhibited two pronounced and opposite redox peaks. The anodic and cathodic peak currents were -56.3 \u0026mu;A and 65.6 \u0026mu;A, respectively, indicating that the electrode works well and can be used for subsequent experimental studies. Upon modifying the electrode with COF, a slight decrease in peak currents was observed. The anodic peak current (Ipa) decreased to -51.0 \u0026mu;A, while the cathodic peak current (Ipc) dropped to 58.1 \u0026mu;A. This confirms the successful immobilization of the COF material on the electrode surface, likely due to its poor conductivity as an organic material, which hindered efficient electron transfer\u003csup\u003e\u0026nbsp;[42]\u003c/sup\u003e. In contrast, AuNCs@COF/SPCE exhibited a significant increase compared to COF/SPCE, with the Ipa and Ipc rising to -57.4 \u0026mu;A and 63.9 \u0026mu;A, respectively. This enhancement was attributed to the superior electrical conductivity of AuNCs, which accelerated the rate of electron transfer. Following UO\u003csub\u003e2\u003c/sub\u003e\u003csup\u003e2+\u0026nbsp;\u003c/sup\u003eaptamer modification, Apt/AuNCs@COF/SPCE displayed a significant decrease in peak currents, with Ipa and Ipc dropping to -41.0 \u0026mu;A and 49.2 \u0026mu;A, respectively. The decrease in conductivity was credited to the electrostatic repulsion between the negatively charged aptamer and the [Fe(CN)\u003csub\u003e6\u003c/sub\u003e]\u003csup\u003e3-/4-\u003c/sup\u003e probes in the electrolyte solution \u003csup\u003e[42, 43]\u003c/sup\u003e, suggesting that the aptamer was adsorbed onto the AuNCs@COF surface. EIS techniques were also used for further assessment of the performance of the various electrodes. The Randle equivalent circuit corresponding to the EIS spectrum was also presented, comprising four elements: charge-transfer resistance (Rct), solution resistance (Rs), Warburg constant (W), and constant phase angle element (CPE). As showed in Fig. 3D, AuNCs@COF behaved the smallest semicircle diameter (1102.2 \u0026Omega;), which was lower than that of the bare SPCE (1311.8 \u0026Omega;), COF/SPCE (2021.3 \u0026Omega;), and Apt/AuNCs@COF/SPCE (4588.3 \u0026Omega;). The result further suggested that the incorporation of AuNCs effectively enhanced the conductivity of the electrodes, thereby improving the electrochemical performance. In conclusion, AuNCs@COF demonstrated outstanding electrochemical properties and served as a promising nanomaterial for applications in electrochemical sensing.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e3.5.\u0026nbsp; \u0026nbsp;\u0026nbsp;Peroxidase-like activity and catalytic mechanism of AuNCs@COF\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe peroxidase-like activity of the AuNCs@COF composite was determined by the TMB-H\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e2\u003c/sub\u003e system in a NaAc-HAc buffered environment. As exhibited in Fig. S2A, only a weak absorption peak at 652 nm was observed in the substrate-only condition, mainly attributed to the auto-oxidative decomposition of H\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e2\u003c/sub\u003e\u003csup\u003e\u0026nbsp;[44]\u003c/sup\u003e. After the introduction of COF, oxTMB showed a slight elevation of the absorption peak at 652 nm, possibly because COF possesses some peroxidase-like activity. Moreover, With the introduction of AuNCs, the UV absorption peak of oxTMB at 652 nm demonstrated a notable elevation imputed to the peroxidase-like activity of AuNCs\u003csup\u003e\u0026nbsp;[39]\u003c/sup\u003e. When the prepared AuNCs@COF was introduced, as predicted, a significantly enhanced UV absorption peak was observed compared to AuNCs alone, indicating a strong peroxidase-like activity of AuNCs@COF. The Michaelis-Menten equation was implemented to perform a steady-state kinetic analysis of AuNCs@COF\u0026apos;s catalytic activity (Fig. S3A and S3B). Typical Lineweaver-Burk double reciprocal plots were generated to ascertain the \u003cem\u003eK\u003csub\u003em\u003c/sub\u003e\u003c/em\u003e and \u003cem\u003ev\u003csub\u003emax\u003c/sub\u003e\u003c/em\u003e of AuNCs@COF nanozyme (Fig. S3C and S3D), and the decreased \u003cem\u003eK\u003csub\u003em\u003c/sub\u003e\u003c/em\u003e indicated a stronger affinity of the enzyme for the substrate. As presented in Table S1, the calculated \u003cem\u003eK\u003csub\u003em\u003c/sub\u003e\u003c/em\u003e and \u003cem\u003ev\u003csub\u003emax\u003c/sub\u003e\u003c/em\u003e were 1.18 mM and 3.04\u0026times;10\u003csup\u003e-4\u003c/sup\u003e mM s\u003csup\u003e-1\u003c/sup\u003e for TMB, and 0.0821 mM and 0.988\u0026times;10\u003csup\u003e-5\u003c/sup\u003e mM s\u003csup\u003e-1\u003c/sup\u003e for H\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e2\u003c/sub\u003e, respectively. These values were compared with those of other peroxide-like nanoenzymes. The results indicated that AuNCs@COF demonstrated favorable peroxidase-like activity, with catalytic performance that is comparable to or superior to that of the referenced nanoenzymes. The excellent enzyme-like activity exhibited by AuNCs@COF can be attributed primarily to the high specific surface area of the COF structure. This characteristic facilitates the uniform dispersion of AuNCs, exposing more active sites. Consequently, substrate molecules will have more opportunities to accumulate on the porous COF via non-covalent interactions, which enhances the contact between the substrate and the catalyst, ultimately improving catalytic efficiency.\u003c/p\u003e\n\u003cp\u003eTo further explained the catalytic activity mechanism of AuNCs@COF, the generation of reactive oxygen species (ROS) generated during the oxidation reaction was initially confirmed through free radical scavenging experiments. Tryptophan (Trp) was utilized as \u003csup\u003e1\u003c/sup\u003eO\u003csub\u003e2\u003c/sub\u003e trapping agent, p-benzoquinone (PBQ) as \u0026bull;O\u003csub\u003e2\u003c/sub\u003e\u003csup\u003e-\u003c/sup\u003e trapping agent, and isopropyl alcohol (IPA) as \u0026bull;OH trapping agent, respectively. As depicted in Fig. S2B, the absorbance decreased following treatment with each of the three scavengers, with the most significant change observed after IPA treatment. This suggests that \u0026bull;OH was the dominant substance in the catalytic process of AuNCs@COF nanoenzymes. Electron paramagnetic resonance (EPR) experiments also verified this result. As revealed in Fig. S2C, the EPR spectrum displayed characteristic signal peaks corresponding to three radicals captured by 2,2,6,6-tetramethylpiperidine (TEMP) and 5,5-dimethyl-1-pyrrolin N-oxide (DMPO). Notably, the signal peak intensity of the \u0026bull;OH radical dramatically exceeded that of the other radicals, indicating a higher generation of \u0026bull;OH during the catalytic process, substantiating that \u0026bull;OH was the main active substance.\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003eAccording to previous studies\u003csup\u003e\u0026nbsp;[45]\u003c/sup\u003e, AuNCs has exceptional electron transfer ability for H\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e2\u003c/sub\u003e. In conjunction with the previously mentioned experimental studies, the activity mechanism of the prepared AuNCs@COF was inferred. TMB and H\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e2\u003c/sub\u003e molecules were adsorbed onto the surface of AuNCs@COF composite, and TMB contributed lone pair electrons, while H\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e2\u003c/sub\u003e underwent oxidation to form \u0026bull;OH radicals as electrons were transferred through the activation site on AuNCs@COF. Subsequently, the \u0026bull;OH radicals catalyzed the oxidation of TMB to oxTMB.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e3.6.\u0026nbsp; \u0026nbsp;\u0026nbsp;Dual-mode detection of UO\u003csub\u003e2\u003c/sub\u003e\u003csup\u003e2+\u003c/sup\u003e\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eUnder optimal conditions (Fig. S4 and Fig. S5), the constructed dual-mode sensor was employed to detect different concentrations of UO\u003csub\u003e2\u003c/sub\u003e\u003csup\u003e2+\u003c/sup\u003e. As shown in Fig. 4A, the absorbance at 652 nm gradually decreased with increasing UO\u003csub\u003e2\u003c/sub\u003e\u003csup\u003e2+\u003c/sup\u003e concentration in colorimetric mode. Meanwhile, as illustrated in Fig. 4B, there existed a strong linear correlation between the logarithm of UO\u003csub\u003e2\u003c/sub\u003e\u003csup\u003e2+\u003c/sup\u003e concentration and absorbance within the concentration range of 1.36\u0026times;10\u003csup\u003e-10\u003c/sup\u003e mol/L to 1.36\u0026times;10\u003csup\u003e-5\u003c/sup\u003e mol/L. The calibration curve has a strong correlation coefficient (R\u003csup\u003e2\u003c/sup\u003e) of 0.9981 and may be expressed as follows: y = 0.0666 lgC\u003csub\u003eUO\u003c/sub\u003e\u003csub\u003e2\u003c/sub\u003e\u003csub\u003e2+\u003c/sub\u003e + 0.6087. The limit of detection (LOD) was found to be as low as 107 pmol/L using the probabilistic methods recommended by the International Union of Pure and Applied Chemistry (IUPAC). As depicted in Fig. 4C, the electrochemical signal in the electrochemical mode showed an increasing trend with the increase in UO\u003csub\u003e2\u003c/sub\u003e\u003csup\u003e2+\u003c/sup\u003e concentration. In addition, Fig. 4D showed a good linear correlation between the electrochemical signal and the logarithm of the UO\u003csub\u003e2\u003c/sub\u003e\u003csup\u003e2+\u003c/sup\u003e concentration over the concentration range of 5.0\u0026times;10\u003csup\u003e-10\u003c/sup\u003e mol/L to 2.5\u0026times;10\u003csup\u003e-5\u003c/sup\u003e mol/L. The calibration curve equation was y = 2.318 lgC\u003csub\u003eUO\u003c/sub\u003e\u003csub\u003e2\u003c/sub\u003e\u003csub\u003e2+\u003c/sub\u003e + 12.918 with an R\u003csup\u003e2\u003c/sup\u003e of 0.9919 and an LOD of 347 pmol/L. Compared with other UO\u003csub\u003e2\u003c/sub\u003e\u003csup\u003e2+\u003c/sup\u003e detection methods, the dual-mode method we developed has a lower detection limit and a wider linear range, showing excellent sensitivity, and can be used for the detection of lower concentrations of UO\u003csub\u003e2\u003c/sub\u003e\u003csup\u003e2+\u003c/sup\u003e (Table S2).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e3.7.\u0026nbsp; \u0026nbsp;\u0026nbsp;Selectivity, reproducibility, and stability of dual-model method\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eTo evaluate the selectivity of dual-mode sensor, the effect of 50-fold concentration of 17 potential interfering metal ions (K\u003csup\u003e+\u003c/sup\u003e, Na\u003csup\u003e+\u003c/sup\u003e, Ag\u003csup\u003e+\u003c/sup\u003e, Ba\u003csup\u003e2+\u003c/sup\u003e, Cd\u003csup\u003e2+\u003c/sup\u003e, Co\u003csup\u003e2+\u003c/sup\u003e, Hg\u003csup\u003e2+\u003c/sup\u003e, Zn\u003csup\u003e2+\u003c/sup\u003e, Mg\u003csup\u003e2+\u003c/sup\u003e, Pb\u003csup\u003e2+\u003c/sup\u003e, Cu\u003csup\u003e2+\u003c/sup\u003e, Mn\u003csup\u003e2+\u003c/sup\u003e, Ca\u003csup\u003e2+\u003c/sup\u003e, Nd\u003csup\u003e3+\u003c/sup\u003e, La\u003csup\u003e3+\u003c/sup\u003e, Fe\u003csup\u003e3+\u003c/sup\u003e, V\u003csup\u003e5+\u003c/sup\u003e) on the quantitative detection of UO\u003csub\u003e2\u003c/sub\u003e\u003csup\u003e2+\u003c/sup\u003e was investigated. As shown in Fig. S6A and S6B, the signals remained largely unchanged in the presence of interfering ions, whether alone or in combination. In contrast, both colorimetric and electrochemical signals demonstrated a marked response following the introduction of UO\u003csub\u003e2\u003c/sub\u003e\u003csup\u003e2+\u003c/sup\u003e. These results confirmed that the developed dual-mode sensor possesses excellent selectivity for UO₂\u0026sup2;⁺ detection.\u003c/p\u003e\n\u003cp\u003eTo evaluate the reproducibility of the system, 11 different dual-mode sensors were tested in parallel. The relative standard deviation (RSD) for the colorimetric and electrochemical modes was determined to be 2.53% and 1.98%, respectively (Fig. S7A and S7B), confirming the sensor\u0026apos;s excellent reproducibility. Furthermore, the stability of the electrochemical sensor was evaluated by measuring its response signals at multiple time points (1 day, 2 days, 5 days, 8 days, 9 days, 10 days, and 15 days) while maintaining consistent experimental conditions. The results showed that the current signal retained 89.70% of its initial value even after 15 days (Fig. S7C), demonstrating the sensor\u0026apos;s satisfactory stability.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e3.8.\u0026nbsp; \u0026nbsp;\u0026nbsp;Analysis of UO\u003csub\u003e2\u003c/sub\u003e\u003csup\u003e2+\u003c/sup\u003e in water samples\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eTo assess the practical detection performance of the developed colorimetric and electrochemical dual-mode sensor, a standard addition assay was performed to analyze varying concentrations of UO\u003csub\u003e2\u003c/sub\u003e\u003csup\u003e2+\u003c/sup\u003e in tap water and Xiangjiang River samples. The findings of the experiment were presented in Table 1. The colorimetric sensor demonstrated recovery rates between 97.46% and 101.01% in tap water, and between 92.25% and 104.52% in Xiangjiang River water, accompanied by RSD values ranging from 1.98% to 8.93%. Similarly, the electrochemical sensor demonstrated average recoveries of 94.02% to 101.37% and 95.14% to 102.81% in tap water and Xiangjiang River water samples, respectively, with RSD values between 1.71% and 6.01%. The RSD values of the dual-mode sensor were consistently below 8.93%, confirming the reliability of the detection results. In summary, the dual-mode method was suitable for detecting UO\u003csub\u003e2\u003c/sub\u003e\u003csup\u003e2+\u003c/sup\u003e in real environmental samples.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 1\u003c/strong\u003e Results for the determination of UO\u003csub\u003e2\u003c/sub\u003e\u003csup\u003e2+\u003c/sup\u003e in real samples.\u003c/p\u003e\n\u003ctable border=\"0\" cellspacing=\"0\" cellpadding=\"0\" width=\"557\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"2\" style=\"width: 14.5113%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eSample\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"4\" style=\"width: 31.1723%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eColorimetric method\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"4\" style=\"width: 31.1723%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eElectrochemical method\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 8.7336%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eAdded\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e(M)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 8.7336%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eFound\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e(M)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 8.7336%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eRecovery\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e(%)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 4.8371%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eRSD\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e(n=3, %)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 8.7336%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eAdded\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e(M)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 8.7336%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eFound\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e(M)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 8.7336%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eRecovery\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e(%)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 4.8371%;\"\u003e\n \u003cp\u003e\u003cstrong\u003eRSD\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e(n=3, %)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"3\" style=\"width: 14.5113%;\"\u003e\n \u003cp\u003eTap water\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 8.7336%;\"\u003e\n \u003cp\u003e1.36\u0026times;10\u003csup\u003e-8\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 8.7336%;\"\u003e\n \u003cp\u003e1.38\u0026times;10\u003csup\u003e-8\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 8.7336%;\"\u003e\n \u003cp\u003e101.01\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 4.8371%;\"\u003e\n \u003cp\u003e5.32\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 8.7336%;\"\u003e\n \u003cp\u003e5.00\u0026times;10\u003csup\u003e-8\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 8.7336%;\"\u003e\n \u003cp\u003e5.07\u0026times;10\u003csup\u003e-8\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 8.7336%;\"\u003e\n \u003cp\u003e101.37\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 4.8371%;\"\u003e\n \u003cp\u003e2.93\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 8.7336%;\"\u003e\n \u003cp\u003e1.36\u0026times;10\u003csup\u003e-7\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 8.7336%;\"\u003e\n \u003cp\u003e1.36\u0026times;10\u003csup\u003e-7\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 8.7336%;\"\u003e\n \u003cp\u003e100.04\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 4.8371%;\"\u003e\n \u003cp\u003e4.04\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 8.7336%;\"\u003e\n \u003cp\u003e5.00\u0026times;10\u003csup\u003e-7\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 8.7336%;\"\u003e\n \u003cp\u003e4.70\u0026times;10\u003csup\u003e-7\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 8.7336%;\"\u003e\n \u003cp\u003e94.02\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 4.8371%;\"\u003e\n \u003cp\u003e1.71\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 8.7336%;\"\u003e\n \u003cp\u003e6.82\u0026times;10\u003csup\u003e-6\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 8.7336%;\"\u003e\n \u003cp\u003e6.65\u0026times;10\u003csup\u003e-6\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 8.7336%;\"\u003e\n \u003cp\u003e97.46\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 4.8371%;\"\u003e\n \u003cp\u003e8.93\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 8.7336%;\"\u003e\n \u003cp\u003e1.00\u0026times;10\u003csup\u003e-5\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 8.7336%;\"\u003e\n \u003cp\u003e1.00\u0026times;10\u003csup\u003e-5\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 8.7336%;\"\u003e\n \u003cp\u003e99.97\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 4.8371%;\"\u003e\n \u003cp\u003e5.71\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"3\" style=\"width: 14.5113%;\"\u003e\n \u003cp\u003eXiangjiangRiver\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 8.7336%;\"\u003e\n \u003cp\u003e1.36\u0026times;10\u003csup\u003e-8\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 8.7336%;\"\u003e\n \u003cp\u003e1.43\u0026times;10\u003csup\u003e-8\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 8.7336%;\"\u003e\n \u003cp\u003e104.52\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 4.8371%;\"\u003e\n \u003cp\u003e3.95\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 8.7336%;\"\u003e\n \u003cp\u003e5.00\u0026times;10\u003csup\u003e-8\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 8.7336%;\"\u003e\n \u003cp\u003e5.10\u0026times;10\u003csup\u003e-8\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 8.7336%;\"\u003e\n \u003cp\u003e102.04\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 4.8371%;\"\u003e\n \u003cp\u003e4.00\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 8.7336%;\"\u003e\n \u003cp\u003e1.36\u0026times;10\u003csup\u003e-7\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 8.7336%;\"\u003e\n \u003cp\u003e1.26\u0026times;10\u003csup\u003e-7\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 8.7336%;\"\u003e\n \u003cp\u003e92.25\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 4.8371%;\"\u003e\n \u003cp\u003e2.01\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 8.7336%;\"\u003e\n \u003cp\u003e5.00\u0026times;10\u003csup\u003e-7\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 8.7336%;\"\u003e\n \u003cp\u003e5.14\u0026times;10\u003csup\u003e-7\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 8.7336%;\"\u003e\n \u003cp\u003e102.81\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 4.8371%;\"\u003e\n \u003cp\u003e1.73\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 8.7336%;\"\u003e\n \u003cp\u003e6.82\u0026times;10\u003csup\u003e-6\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 8.7336%;\"\u003e\n \u003cp\u003e6.78\u0026times;10\u003csup\u003e-6\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 8.7336%;\"\u003e\n \u003cp\u003e99.48\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 4.8371%;\"\u003e\n \u003cp\u003e1.98\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 8.7336%;\"\u003e\n \u003cp\u003e1.00\u0026times;10\u003csup\u003e-5\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 8.7336%;\"\u003e\n \u003cp\u003e9.51\u0026times;10\u003csup\u003e-6\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 8.7336%;\"\u003e\n \u003cp\u003e95.14\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 4.8371%;\"\u003e\n \u003cp\u003e6.01\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e"},{"header":"4.\tConclusion","content":"\u003cp\u003eHerein, a novel colorimetric and electrochemical dual-mode sensor was established for the detection of UO\u003csub\u003e2\u003c/sub\u003e\u003csup\u003e2+\u003c/sup\u003e by integrated the peroxidase-like catalytic activity and electrochemical properties of synthesized AuNCs@COF with an aptamer as the regulatory and recognition element. The dual-mode sensor constructed has a lower detection limit and can be mutually validated through the combination of colorimetric and electrochemical methods, improving the accuracy of detection. The colorimetric mode had a linear range of 1.36\u0026times;10\u003csup\u003e-10\u003c/sup\u003e - 1.36\u0026times;10\u003csup\u003e-5\u003c/sup\u003e mol/L with an LOD of 107 pmol/L, and the electrochemical mode had a linear range of 5.0\u0026times;10\u003csup\u003e-10\u003c/sup\u003e - 2.5\u0026times;10\u003csup\u003e-5\u003c/sup\u003e mol/L with an LOD of 347 pmol/L. This method exhibited good specificity, stability and repeatability, while better results were achieved in the application of testing actual water samples of tap water and Xiangjiang River water. As a result, we expected that this dual-mode sensor has the potential to detect and analyze different types of uranium-containing samples.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eCRediT authorship contribution statement\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eZhijun Chen:\u003c/strong\u003e Writing - original draft, Formal analysis, Visualization, Data curation. \u003cstrong\u003eJinquan Liu:\u003c/strong\u003e Writing - review \u0026amp; editing, Supervision, Conceptualization. \u003cstrong\u003eWenyu Wang:\u0026nbsp;\u003c/strong\u003eMethodology, Investigation. \u003cstrong\u003eGuoqing Qin:\u0026nbsp;\u003c/strong\u003eValidation. \u003cstrong\u003eSiru Liu:\u003c/strong\u003e Validation.\u003cstrong\u003e\u0026nbsp;Weilin Zhang:\u003c/strong\u003e Investigation. \u003cstrong\u003eChangmin Peng:\u003c/strong\u003e Investigation. \u003cstrong\u003eYan Tan:\u003c/strong\u003e Resources. \u003cstrong\u003eZhongran Dai:\u003c/strong\u003e Resources. \u003cstrong\u003eDeshuai Zhen:\u003c/strong\u003e Resources. \u003cstrong\u003eLe Li:\u003c/strong\u003e Resources, Project administration.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eDeclaration of Competing Interest\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare no financial conflicts of interest.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis work was supported by the National Natural Science Foundation of China (No. 12175103 and 82304195), the Natural Science Foundation of Hunan Province (No. 2023JJ50127) and the Open Funding of State Environmental Protection Key Laboratory of Monitoring for Heavy Metal Pollutants (No. KLMHM202434).\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eF B Xiao, H Li, P Xie, J Liu, W F Du, L Li, S Y Yang, Z Y Wu. 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Sensor Actuat B-Chem, 2021, 326: 128850.\u003c/li\u003e\n\u003c/ol\u003e"},{"header":"Scheme 1","content":"\u003cp\u003eScheme 1 is available in the Supplementary Files section.\u003c/p\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"microchimica-acta","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"miac","sideBox":"Learn more about [Microchimica Acta](https://link.springer.com/journal/604)","snPcode":"604","submissionUrl":"https://submission.springernature.com/new-submission/604/3","title":"Microchimica Acta","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"Uranyl Ion, Gold nanoclusters, Covalent organic frameworks, Electrochemistry, Colorimetry","lastPublishedDoi":"10.21203/rs.3.rs-5971480/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-5971480/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"In this context, an innovative dual-mode colorimetric and electrochemical sensor was developed for the detection of uranyl ions (UO22+), utilizing a covalent organic framework@gold nanoclusters (AuNCs@COF) composite. The synthesis of AuNCs@COF was simple, and the incorporation of AuNCs imparted the composite with exceptional peroxidase-like catalytic activity and enhanced electrochemical properties. By regulating the adsorption and desorption of aptamers on the AuNCs@COF surface, both peroxidase-like activity and conductivity were modulated, enabling the detection of UO22+ utilizing colorimetric and electrochemical dual signals. Under optimal conditions, the sensor revealed a broad linear detection range and a low detection limit, with ranges of 1.36×10-10 - 1.36×10-5 mol/L for colorimetric detection and 5.0×10-10 - 2.5×10-5 mol/L for electrochemical detection, achieving detection limits of 107 pmol/L and 347 pmol/L, respectively. Unlike other single-mode sensor for UO22+ detection, this dual-mode sensor demonstrated superior sensitivity, specificity, and repeatability. Furthermore, the results of spiked recovery experiments in real water samples highlight the promising potential of this dual-mode sensor for environmental water monitoring applications.","manuscriptTitle":"Aptamer-regulated colorimetric and electrochemical dual-mode sensor for the detection of uranyl ions utilizing AuNCs@COF composite","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-02-10 07:23:42","doi":"10.21203/rs.3.rs-5971480/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2025-02-20T18:55:50+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-02-17T18:07:50+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-02-14T10:02:10+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"237552228741301545498849070806483672874","date":"2025-02-13T05:38:24+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"192324599329161391231097526088866611037","date":"2025-02-13T03:42:14+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"189666353263292973759712289173489494547","date":"2025-02-09T19:22:13+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"110555915104743686438584008048092308788","date":"2025-02-08T15:52:00+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-02-08T04:06:45+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"31866148333204633776050513586924094155","date":"2025-02-08T03:57:21+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"120989024678825450377590453011221922701","date":"2025-02-08T01:00:56+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-02-07T21:16:26+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-02-07T07:47:42+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-02-07T07:45:10+00:00","index":"","fulltext":""},{"type":"submitted","content":"Microchimica Acta","date":"2025-02-06T08:23:13+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"microchimica-acta","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"miac","sideBox":"Learn more about [Microchimica Acta](https://link.springer.com/journal/604)","snPcode":"604","submissionUrl":"https://submission.springernature.com/new-submission/604/3","title":"Microchimica Acta","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"ee595561-3bfc-410b-8040-5f0977c21da5","owner":[],"postedDate":"February 10th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2025-04-21T16:02:05+00:00","versionOfRecord":{"articleIdentity":"rs-5971480","link":"https://doi.org/10.1007/s00604-025-07156-3","journal":{"identity":"microchimica-acta","isVorOnly":false,"title":"Microchimica Acta"},"publishedOn":"2025-04-14 15:57:10","publishedOnDateReadable":"April 14th, 2025"},"versionCreatedAt":"2025-02-10 07:23:42","video":"","vorDoi":"10.1007/s00604-025-07156-3","vorDoiUrl":"https://doi.org/10.1007/s00604-025-07156-3","workflowStages":[]},"version":"v1","identity":"rs-5971480","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-5971480","identity":"rs-5971480","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}