Sensitive and selective fluorescent switch for Detection of Fe (III) Ion in Human urine Using luminol-functionalized Functionalized Graphene Quantum dots

Sensitive and selective fluorescent switch for Detection of Fe (III) Ion in Human urine Using luminol-functionalized Functionalized Graphene Quantum dots | 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 Sensitive and selective fluorescent switch for Detection of Fe (III) Ion in Human urine Using luminol-functionalized Functionalized Graphene Quantum dots Noura H Harran, Bassam F alfarhani This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-4572322/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 30 Sep, 2024 Read the published version in Chemical Papers → Version 1 posted 5 You are reading this latest preprint version Abstract A fluorescent switch based on graphene quantum dots (GQDs) has been synthesized and modified using Luminol to detect Fe (III) in human urine selectively. The pyrolysis of anhydrous citric acids produced GQDs abundant in amino groups. The luminol modification shows distinct optical characteristics, improving the fluorescence intensity by approximately 6.41 times compared to GQD alone. The probe employs static quenching to initiate the fluorescence response by utilizing the interaction between Fe (III) and Luminol-GQDs, resulting in the suppression of fluorescence. The probe is capable of detecting Fe (III) in both a pure aqueous solution and synthetic urine. Furthermore, it is also able to detect Fe (III) in human urine. The concentration of Fe (III) required to quench the fluorescence intensity of Luminol-GQDs exhibits a strong linear relationship. A good linear relationship was obtained for Fe (III) concentrations ranging from 50 to 400 µM. Notably, this sensitivity surpasses that of earlier studies. The detection limit of Fe (III) using Luminol-GQDs is approximately 1.5 µM. The real sample detection was conducted using a human urine sample, and satisfactory recoveries of approximately 94.57% were achieved. Luminol-mGQDs Nanosensor Fe+3 detection Fluorescent assay Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10 Figure 11 1. Introduction Different diseases can cause a rise in the amount of iron excreted in the urine. (1) Hemolytic diseases: Individuals with substantial intravascular hemolysis, such as sickle cell anaemia, may experience elevated urine excretion of haemoglobin iron, reaching levels as high as 10.75 mg per 24 hours [ 3 , 4 ]. Most iron expelled from the body is hemosiderin, and ferritin can also be found in the urine. Chronic kidney disease (CKD) is a medical condition characterized by long-term damage to the kidneys. Urine iron excretion in individuals with chronic kidney disease (CKD) is strongly linked to urine C-megalin. This marker indicates the metabolic burden on the proximal tubular epithelial cells (PTECs) in the remaining functional nephrons, mediated by megalin. Urine iron levels are linked to urine 8-OHdG, a sign of oxidative stress [ 5 ] and iron excess [ 3 ]. Consequently, our research, which aims to enhance the quality of human healthcare by quantifying Fe (III)ions, is of utmost importance. Graphene quantum dots (GQDs) have recently been identified as a promising platform for detecting Fe (III)ions due to their minimal toxicity, excellent water solubility, and ability to maintain their fluorescence under light exposure. [ 6 – 11 ] Nevertheless, the GQDs demonstrate a low detection limit (LOD) for the Fe (III)ions due to the limited quantity of surface active sites. Numerous studies have been conducted to improve the active sites on the GQDs and address these challenges. Functionalized graphene quantum dots (GQDs) containing amino groups, such as amine N, have several active sites contributing to their exceptional ability to detect Fe (III)ions. [ 12 ] Furthermore, using a surfactant (such as PPy) for surface passivation led to the acquisition of GQDs with a narrower distribution and smaller size, ultimately resulting in an increased specific surface area. [ 13 ] The detection performance for Fe (III)ions was improved because there are numerous active sites on the GQDs due to the increased specific surface area. Therefore, surface passivation and functionalization of GQDs with amine N groups can enhance the active sites, which can potentially play a crucial role in improving the Fe (III)detection limit. [ 14 – 16 ]. This study (illustrated in Fig. 1 ), is dedicated to developing a fluorescent material probe by functionalizing GQD with luminol. The probe has a remarkable ability to detect Fe(III). The modified graphene quantum dot (GQD) can be readily synthesized using a one-step hydrothermal synthesis method, with anhydrous citric acid as the precursor. The obtained Luminol-GQDs possess a consistent size and a graphene structure consisting of a single layer. Furthermore, Luminol-GQDs exhibit a vibrant light blue fluorescence. Adding Fe (III) ions will significantly reduce the fluorescence intensity of the Luminol-GQD. This assay offers a novel approach for detecting Fe (III)ions. Furthermore, the suitability of Luminol-GQDs was confirmed by performing a human urine analysis. 2. Experimental 2.1. Materials Anhydrous citric acid (99.5-100.5%), sodium hydroxide (98%), 3-(trimethoxysilyl)propyl methacrylate (98%), luminol (97%), and Fe (III) chloride hexahydrate (97%) were all obtained from Sigma-Aldrich. Hydrochloric acid (35–38%) was obtained from BDH, and artificial urine(from nanomer corporation) (pH = 6.5) with analytical purity was used as received without any additional purification. All experiments were conducted using ultra-pure water with a resistivity of 18MΩ. 2.2. Instrumentation The UV-1800 spectrophotometer (Shimadzu, Japan) was used to measure the ultraviolet-visible (UV-vis) absorption spectra. Fluorescence spectroscopy RF-5301PC (Shimadzu, Japan) was used to conduct steady-state fluorescence observations at room temperature. The GQDs were dissolved in water and transferred into a quartz cuvette with four polished windows. The excitation and emission monochromators were set to a slit-width of 5 nm. The ATR-FTIR spectra were acquired using a TENSOR 27 FT-IR spectrophotometer. Aeris-Benchtop X-ray Diffractometers (Malvern Panalytical) were used to conduct X-ray powder diffraction (XRD) patterns. The dimensions and structure of GQDs were analyzed using transmission electron microscopy (TEM) with a 100KV electron microscope, namely the Philips model CM120. SEM data were acquired using the Axia ChemiSEM instrument from the Netherlands. 2.3. Synthesis of GQDs The GQDs were prepared by directly pyrolyzing citric acid. First, 1.92 g of anhydrous-citric acid was heated to 200°C using a hotplate. 5 minutes later, the citric acid was liquefied, and a color change was observed to be pale yellow and turn into a reddish-orange color collide of GQDs in 25 min. Notice that further heating times must avoided to prevent the formation of dark graphene oxide. The obtained reddish-orange liquid was added dropwise into 10 mg mL − 1 NaOH (100 mL) under vigorous stirring for 10 min until thoroughly mixed. After mixing, the solution was neutralized by adding HCl drops (10 mg mL − 1 ) to obtain pH 7. As a result, a yellowish green GQDs solution was produced. The GQDs solution was filtered using a syringe filter (0.22µm pore size) twice to remove the residual reagents, and the obtained filtrate was then collected and dialyzed using a 1000Da dialysis bag for 8 hours. The resulting solution was then freeze-dried to obtain GQDs powder.[ 13 ]. Synthesis of Luminol-GQDs 0.2 mL of 3 (Trimethoxysilyl)propyl methacrylate (TMPMS) was added to 100 mL of the GQDs solution and the mixture was stirred for 24 h at room temperature and was then freeze-dried to obtain mGQDs powder. Then, the luminol-modified GQDs were synthesized by adding 0.02 mg ml − 1 of Luminol solution into 100 ml of 4 mg mL − 1 NaOH solution For the synthesis of Luminol-GQDs, GQDs (2 mg ml − 1 ) and luminol were added to sodium hydroxide (4 mg ml − 1 ) followed by 30 min ultrasonic treatment. the resulting mixture was transferred into a polytetrafluoroethylene-lined autoclave and reacted at 180°C for 8 h. After cooling to room temperature, the product was filtered using a syringe filter with a 0.22µm pore size. Followed by freeze-drying to obtain luminol-GQD power. 2.4. Detection procedure for Fe (III) ions Stock standard solutions 2.7 mg ml -1 Fe (III) were prepared by dissolving an appropriate amount of FeCl 3 .6H 2 O in artificial urine and adjusting the volume to 20 mL in a volumetric flask. It was further diluted to known concentrations using stepwise preparation. A fixed concentration of Luminol-GQDs was transferred to a fluorescent cuvette. The fluorescent intensity of the solution immediately was recorded from 367 to 600 nm with an excitation wavelength fixed at a wavelength that shows the highest intensity in 314 nanometers. After an appropriate amount of Fe (III) ions was added, the fluorescent intensity of the solution was again recorded. A similar procedure was performed for various pre-determined concentrations of Fe ions. For the sake of comparison, the volume of Luminol-GQDs solution was fixed to be 2 mL before the addition of Fe (III) All measurements were made at room temperature. 3. Results and discussion 3.1 Morphological analysis and characterization Prior to its application as a fluorescent probe for Fe(III) detection, the synthesized modified GQD was subjected to characterization in order to verify its structural and optical features. Figure (2, a) displays the X-ray diffraction (XRD) patterns of graphene quantum dots (GQDs), revealing the presence of three distinct diffraction peaks. [17,18] The peak observed at an angle of 27.06 degrees (2θ) corresponds to the crystallographic plane labeled as (002) in graphene. Additionally, there are other peaks present, The angles 2θ = 31.3 and 45.1 degrees correspond to the crystallographic planes (100) and (102). The presence of three distinct diffraction peaks indicates a high level of sharpness, thereby confirming the excellent crystallinity of the produced GQDs (Fig. 2.b). Sherrer's equation was utilized to estimate the average size, denoted as L, of the nanoparticles in the processed samples. Based on Scherrer's equation, the grain size D may be estimated using the formula D = Klambda∕βcosθ. In this equation, the constant K is equal to 0.942, the x-ray wavelength λ is 0.15405 nm, the diffraction peak half-height width β is 0.247, and the diffraction angle θ is 13.4 degrees. Using these values, the calculated grain size D is 33.3 nm. However, in the case of a sample with a small particle size, the grain size determined by XRD is more than the actual size. The morphology and structure of GQD were examined using field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). Despite the challenge of obtaining high-quality TEM pictures due to the poor electro-contrast between the GQDs and the carbon-coated TEM grids, it is nevertheless possible to discern nanosheets measuring 20 nm in size (Fig. 3. c). This image displays graphene quantum dots (GQDs) with a diameter of around 20 nanometers and a spherical shape. Field-emission scanning electron microscopy (FESEM) is a sophisticated imaging method that allows for the detailed examination of the surface structure and shape of graphene quantum dots (GQDs) with high precision. When GQDs are observed using FESEM (as shown in Fig. 3. a and b), they typically appear as a cluster of small, spherical particles with sizes ranging from a few nanometers. The particles' surface morphology and texture can vary based on the synthesis and processing method. The compositions and dispersion of the element were determined using EDX-mapping (Fig. 3. d,e, and f). The field emission scanning electron microscope (FE-SEM) reveals a detailed surface morphology, displaying the variations in surface texture of the created modified GQDs indicating the distribution of elements. The chemical composition of the modified GQDs was analyzed using energy dispersive X-ray (EDX) spectroscopy, and the corresponding results are presented in Fig. 2. g. Graphene quantum dots (GQDs) exhibit a consistent circular morphology. The Fourier-transform infrared (FT-IR) spectra of graphene quantum dots are presented in Fig. 4. a. The GQDs were functionalized using 3-(trimethoxysilyl)propyl methacrylate, resulting in broad absorption peaks at around 1376.20 cm−1 and 1550.49 cm −1 . These peaks are attributed to the stretching vibrations of symmetric and asymmetric carboxyl groups, respectively. Additionally, a stretching vibration of C-OH was observed below 1350 cm -1 , and broadband around 3347.19 cm −1 was attributed to the stretching vibration of hydroxyl groups. [19] In Fig.4.b the use of luminol reveals the presence of C=O and asymmetric carboxyl group bonds at around 1571 and 1413 cm -1 , respectively. Additionally, a large peak at 3500 cm -1 indicates the stretching vibration of the N-H bond in luminol. The presence of a band at approximately 1413 cm -1 can be attributed to the absorption of C–N bonds. In contrast, a band at roughly 704 cm -1 is associated with the out-of-plane bending of C-H aromatic bonds. Identifying a peak at 3100 cm -1 indicated the presence of N–H stretching vibration in the amine groups, confirming the successful integration of nitrogen atoms. 3.2 Optical properties Figure 5 depicts the UV-Vis absorption spectra of the modified graphene quantum dots (GQDs) samples. The GQDs display a weak peak at 360 nm due to the n-π* transition in C=O groups, an identifiable band for the modified GQDs. The fluorescence spectra in Fig.6 indicate that the highest fluorescence emission of GQDs occurred at wavelengths 465 nm while blue shifting with 428 nm maximum wavelength in the luminol-GQD was noticed due to fractionalization, respectively. The Luminol-GQD produced in its original form demonstrates a high level of fluorescence emission and possesses surface functionalization that is distinctive to nitrogen. The hydrophilicity of the GQDs, which is responsible for their high solubility in water, is a result of the presence of these functional groups. Due to the existence of these functional groups and intense emission, these Luminol-GQDs are anticipated to be an optimal choice for fluorescence sensing. The relationship between the emission wavelength and the excitation has been investigated, and Figure 7 displays the fluorescence spectra of the Luminol-GQDs solution at different excitation wavelengths. The Figure demonstrates that the emission maximum wavelength remains constant regardless of the selected excitation wavelength. The emission of graphene quantum dots is unaffected by excitation, indicating that the size and surface state of the sp2 clusters within GQDs are uniform. 3.3 Selective detection of Fe (III)ion Synthetic urine has been proven to exhibit a significant matrix profile when analyzed using various analytical methods. Fluorescence spectrophotometry limits the matrix effect by utilizing the selectivity of fluorescence for certain molecules that impact the analysis. Monitoring the effect of the matrix by detecting Fe(III) ions in artificial urine before analyzing real human urine was first tested. To achieve this goal, the selective sensing of Fe(III) was carried out using excitation/emission wavelengths of 314/428 nm and a pH of 7.4 in a phosphate buffer saline solution containing Luminol-GQDs using Synthetic urine as the solution media, with a concentration of 0.0819 g in 40 ml of GQD. The excitation wavelength of 314 nm was chosen as it resulted in the strongest fluorescence emission. Thus, this specific wavelength was chosen to observe and measure the impact of Fe(III) ions on fluorescence intensity. The fluorescence intensities of Luminol-GQD were measured upon introducing different concentrations of ferric ions (Fig. 8). The results indicate that Luminol-GQD has a strong ability to detect Fe (III) specifically. The process of fluorescence quenching is associated with the high attraction of Fe (III) ions to the amino group of Luminol-GQD, resulting in the formation of a stable complex. T o elucidate the potential mechanism of our detecting system, an endeavor to establish a correlation between the concentration of Fe (III) ions and the luminescence intensity of Luminol-GQDs was done by employing the Stern-Volmer relationship. Fig. 9 depicts the Stern-Volmer analysis of the quenching experiment. Specifically, the ratio of initial fluorescence intensity to the fluorescence intensity after quenching (F0/F), plotted against the concentration of Fe(III). The linear relationship of the Stern-Volmer Plot over the concentration range of Fe (III) ions from 50 to 300 μM is notable. This behavior indicates that a statistic mechanism involving charge transfer likely controls the interaction between GQDs and Fe(III) ions The regression value (R 2 ) was found to be 0.9901 which reflects a linear relation between the quencher concentration and fluorescence intensity, the obtained R 2 value indicates a linear relation between the quencher concentration and fluorescence intensity. The findings indicate that the produced Luminol-GQD can be a selective and sensitive sensor for detecting Fe(III) ions in artificial urine. The formulas for determining the limit of detection (LOD, equation 1) and limit of quantification (LOQ, equation 2) are below An abrupt decrease in photoluminescence (PL) was seen upon introducing Fe(III). The fluorescence quenching was examined at Fe(III) concentrations ranging from 1 to 300 μM. A valid linear correlation was observed, as shown in Fig. 10, demonstrating a strong linear association. LOD = 3.3* σ /S LOQ = 10 * σ /S where σ is the standard deviation of the intercept and S is the slope of the linear regression plot. The LOD and LOQ were calculated to be 1.5 μM and 5.2 μM, respectively. The detection limit of Fe (III)found in this study was much lower than the reported studies in Table 1 Table 1 . Comparison of Fe (III) Sensing Properties of the Luminol-GQD with Those of Recently Reported GQDs materials technique in detail detection limit (μM) Analysis time ref Luminol-GQD hydrothermal method 1.5 24h 20 N-doped GQDs ammonia through hydrothermal method 1 >24 21 GQDs chemical oxidation 60 >26h 22 N-doped GQDs microwave synthesis 100 >27h 23 GQDs electrochemical synthesis 7.22 -- 24 Graphitic GQDs electrochemical synthesis 2 >96 h 25 N-doped/amino GQDs chemical oxidation 0.5 >24 26 N-doped GQDs hydrothermal method 0.5 >12 h 27 3.4 Analysis of Fe (III)in human urine sample The fluorescence sensor was utilized to detect Fe(III) ions in real human urine samples, demonstrating the capabilities of the probe. Healthy volunteers provided human urine samples, which were collected following the international standard for manual urine collection. The urine liquid was either analyzed immediately or held at a temperature of -20°C until it could be analyzed. Prior to the analysis, the urine samples were spiked with varying quantities of Fe(III). In order to assess the repeatability of the suggested approach (e.g., precision), each sample was analyzed five times using the same working conditions within a single day. Fig. 11. Display the emission fluorescence of the modified graphene quantum dots (GQD) both before and after the addition of a quencher. The implemented technique achieves a 94.75% recovery of Fe(III) ions in urine samples, with a Relative Standard Deviation (RSD) of 4.12%. This demonstrates the practicality of the suggested method for directly analyzing Fe(III) in human urine without the need for dilution or pre-treatment. Conclusion A novel technique has been developed to rapidly and easily analyze Fe(III) ions in human urine with remarkable selectivity. This study utilized room temperature fluorescence to monitor the quenching signal caused by Fe(III) ions, enabling a direct detection of Fe(III) ions. This study represents the first report (to the best of our knowledge) on utilizing Luminol-GQD as a sensor for detecting Fe(III) ions in human urine. The findings of our study demonstrate that this approach exhibits a high level of recovery, a remarkably short period for analysis, and a distinct linear relationship within the chosen concentration range. Declarations On behalf of all authors, the corresponding author states that there is no conflict of interest. References Yao, Q., et al., One-pot synthesis of fluorescent nitrogen-doped graphene quantum dots for portable detection of iron ion. Current Applied Physics, 2022. 41 : p. 191-199. Sreeja, K., et al., Fluorine-rich graphene quantum dots by selective oxidative cutting of hydroxy fluorographene and their application for sensing of Fe (III) ions. Journal of Fluorine Chemistry, 2023. 268 : p. 110130. SEARS, D.A., et al., Urinary iron excretion and renal metabolism of hemoglobin in hemolytic diseases. Blood, 1966. 28 (5): p. 708-725. Washington, R. and D.R. Boggs, Urinary iron in patients with sickle cell anemia. The Journal of Laboratory and Clinical Medicine, 1975. 86 (1): p. 17-23. Nakatani, S., et al., Urinary iron excretion is associated with urinary full-length megalin and renal oxidative stress in chronic kidney disease. Kidney and Blood Pressure Research, 2018. 43 (2): p. 458-470. Yoo, D., et al., Carbon dots as an effective fluorescent sensing platform for metal ion detection. Nanoscale research letters, 2019. 14 : p. 1-13. Zhu, S., et al., Highly photoluminescent carbon dots for multicolor patterning, sensors, and bioimaging. Angewandte Chemie International Edition, 2013. 52 (14): p. 3953-3957. Mohammed, L.J. and K.M. Omer, Carbon dots as new generation materials for nanothermometer. Nanoscale Research Letters, 2020. 15 (1): p. 182. Mohammed, L.J. and K.M. Omer, Dual functional highly luminescence B, N Co-doped carbon nanodots as nanothermometer and Fe3+/Fe2+ sensor. Scientific reports, 2020. 10 (1): p. 3028. Omer, K.M. and M. Sartin, Dual-mode colorimetric and fluorometric probe for ferric ion detection using N-doped carbon dots prepared via hydrothermal synthesis followed by microwave irradiation. Optical Materials, 2019. 94 : p. 330-336. Ananthanarayanan, A., et al., Facile synthesis of graphene quantum dots from 3D graphene and their application for Fe3+ sensing. Advanced Functional Materials, 2014. 24 (20): p. 3021-3026. Li, L., et al., Synthesis of nitrogen-doped and amino acid-functionalized graphene quantum dots from glycine, and their application to the fluorometric determination of ferric ion. Microchimica Acta, 2015. 182 : p. 763-770. Tajik, S., et al., Carbon and graphene quantum dots: A review on syntheses, characterization, biological and sensing applications for neurotransmitter determination. RSC advances, 2020. 10 (26): p. 15406-15429. Mansuriya, B.D. and Z. Altintas, Applications of graphene quantum dots in biomedical sensors. Sensors, 2020. 20 (4): p. 1072. Peng, J., et al., Graphene quantum dots derived from carbon fibers. Nano letters, 2012. 12 (2): p. 844-849. Pan, D., et al., Hydrothermal route for cutting graphene sheets into blue‐luminescent graphene quantum dots. Advanced materials, 2010. 22 (6): p. 734-738. Xu, C., et al., Effects of different pyrolysis preparation condition on the fluorescence properties of graphene quantum dots. Optical Engineering, 2021. 60 (11): p. 117103-117103. Maiti, S., et al., Synthesis of excitation independent highly luminescent graphene quantum dots through perchloric acid oxidation. Langmuir, 2017. 33 (51): p. 14634-14642. Masteri-Farahani, M., S. Mashhadi-Ramezani, and N. Mosleh, Molecularly imprinted polymer containing fluorescent graphene quantum dots as a new fluorescent nanosensor for detection of methamphetamine. Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2020. 229 : p. 118021. Abbas, A., L.T. Mariana, and A.N. Phan, Biomass-waste derived graphene quantum dots and their applications. Carbon, 2018. 140 : p. 77-99. Liu, H.; Na, W.; Liu, Z.; Chen, X.; Su, X. A novel turn-on fluorescent strategy for sensing ascorbic acid using graphene quantum dots as fluorescent probe. Biosens Bioelectron. 2017, 92, 229−233. Van Tam, T.; Trung, N. B.; Kim, H. R.; et al. One-pot synthesis of N-doped graphene quantum dots as a fluorescent sensing platform for Fe3+ ions detection. Sens. Actuators, B 2014, 202, 568−793. Zhu, X.; Zhang, Z.; Xue, Z.; Huang, C.; Shan, Y.; Liu, C.; Qin, X.; Yang, W.; Chen, X.; Wang, T. Understanding the selective detection of Fe3+ based on graphene quantum dots as fluorescent probes: The Ksp of a Metal hydroxide Assisted mechanism. Anal. Chem. 2017, 89, 12054−12058. Ren, Q.; Ga, L.; Ai, J. Rapid Synthesis of Highly Fluorescent Nitrogen-Doped graphene quantum dots for effective detection of ferric ions and as fluorescent ink. ACS Omega 2019, 4, 15842−15848. Ananthanarayanan, A.; Wang, X.; Routh, P.; Sana, B.; Lim, S.; Kim, D. H.; Lim, K. H.; Li, J.; Chen, P. Facile Synthesis of graphene quantum dots from 3D graphene their applications for Fe3+ sensing. Adv. Funct. Mater. 2014, 24, 3021−3026. Zhang, Y. L.; Wang, L.; Zhang, H. C.; Liu, Y.; Wang, H. Y.; Kang, Z. H.; Lee, S. T. Graphitic carbon quantum dots as a fluorescent sensing platform for highly efficient detection of Fe3+ ions. RSC Adv. 2013, 3, 3733−3738. Xu, H.; Zhou, S.; Liu, J.; Wei, Y. Nanospace-confined preparation of uniform nitrogen-doped graphene quantum dots for highly selective fluorescence dual-functional determination of Fe3+ and ascorbic acid. RSC Adv. 2018, 8, 5500−5508. Cite Share Download PDF Status: Published Journal Publication published 30 Sep, 2024 Read the published version in Chemical Papers → Version 1 posted Reviewers agreed at journal 22 Jun, 2024 Reviewers invited by journal 22 Jun, 2024 Editor invited by journal 22 Jun, 2024 Editor assigned by journal 15 Jun, 2024 First submitted to journal 13 Jun, 2024 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. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. 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-4572322","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":317693044,"identity":"647d5cca-001d-4774-a514-838c40555505","order_by":0,"name":"Noura H Harran","email":"","orcid":"","institution":"University of Al-Qadisiyah","correspondingAuthor":false,"prefix":"","firstName":"Noura","middleName":"H","lastName":"Harran","suffix":""},{"id":317693045,"identity":"b45f8345-b08e-43f0-b2cd-d3f4b396838b","order_by":1,"name":"Bassam F alfarhani","email":"data:image/png;base64,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","orcid":"https://orcid.org/0000-0002-5031-8549","institution":"University of Al-Qadisiyah","correspondingAuthor":true,"prefix":"","firstName":"Bassam","middleName":"F","lastName":"alfarhani","suffix":""}],"badges":[],"createdAt":"2024-06-12 20:11:33","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-4572322/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-4572322/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1007/s11696-024-03705-x","type":"published","date":"2024-09-30T15:56:51+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":60160500,"identity":"3284f742-b933-4b7b-84fd-4549a1b05804","added_by":"auto","created_at":"2024-07-12 12:57:05","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":664537,"visible":true,"origin":"","legend":"\u003cp\u003eschematic diagram for sensing process\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-4572322/v1/27da3094777372a789b5e558.png"},{"id":60161155,"identity":"c8d15412-1ac3-4468-8356-6db859794ed2","added_by":"auto","created_at":"2024-07-12 13:05:05","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":558519,"visible":true,"origin":"","legend":"\u003cp\u003eX-Ray Photoelectron Spectroscopy (XPS) full scan survey spectrum: (a)-XRD for GQDs and (b) XRD for the modified GQDs\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-4572322/v1/aa6332bd51d10926e9011e22.png"},{"id":60160498,"identity":"6a58e2e9-1b1b-4c54-b8e8-d35f642189fb","added_by":"auto","created_at":"2024-07-12 12:57:05","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":786468,"visible":true,"origin":"","legend":"\u003cp\u003e(a) Shows FESEM images of modified GQDs (a) Top morphology and (b) scale of diameter, (c) TEM image of the modified GQDs, (d, e, f) EDX sample mapping and (g) elements distribution in the sample\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-4572322/v1/11353780a274f9da66c215ed.png"},{"id":60159459,"identity":"be910d68-a306-472b-83c0-51e0875ea818","added_by":"auto","created_at":"2024-07-12 12:49:05","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":303622,"visible":true,"origin":"","legend":"\u003cp\u003eFTIR spectra of (a) GQDs and (b) Luminol-GQDs\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-4572322/v1/a0fa1d0446081ba032005ad8.png"},{"id":60160499,"identity":"58d64eb5-21f1-4149-9604-cd799d0891de","added_by":"auto","created_at":"2024-07-12 12:57:05","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":147440,"visible":true,"origin":"","legend":"\u003cp\u003eUV-Vis spectra GQDs and Luminol-GQDs in aqueous suspended in water\u003c/p\u003e","description":"","filename":"5.png","url":"https://assets-eu.researchsquare.com/files/rs-4572322/v1/ed30bde1c1ccc33930d57244.png"},{"id":60159458,"identity":"26561e90-348f-438b-898d-a15073428f46","added_by":"auto","created_at":"2024-07-12 12:49:05","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":265802,"visible":true,"origin":"","legend":"\u003cp\u003eFluorescence spectra of GQDs and Luminol-GQDs\u003c/p\u003e","description":"","filename":"6.png","url":"https://assets-eu.researchsquare.com/files/rs-4572322/v1/58bb0197cd60b47b2708494d.png"},{"id":60159464,"identity":"5756b904-8d66-4d2f-94d1-2eef58df0acf","added_by":"auto","created_at":"2024-07-12 12:49:05","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":165776,"visible":true,"origin":"","legend":"\u003cp\u003eFluorescence spectra of Luminol-GQDs at different excitation\u003c/p\u003e","description":"","filename":"7.png","url":"https://assets-eu.researchsquare.com/files/rs-4572322/v1/db55d30cab9184081d0b923f.png"},{"id":60159467,"identity":"e8ed399f-cbd5-45e0-bc0a-3c12fdf938eb","added_by":"auto","created_at":"2024-07-12 12:49:05","extension":"png","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":179610,"visible":true,"origin":"","legend":"\u003cp\u003eFluorescence spectra of Luminol-GQD with different concentrations of Fe(III) prepared in artificial urine (AU)\u003c/p\u003e","description":"","filename":"8.png","url":"https://assets-eu.researchsquare.com/files/rs-4572322/v1/9e33d7b4f2697fbdd45832fe.png"},{"id":60159466,"identity":"e1ba86de-6ea4-48c2-ab1d-bb4063cd1c62","added_by":"auto","created_at":"2024-07-12 12:49:05","extension":"png","order_by":9,"title":"Figure 9","display":"","copyAsset":false,"role":"figure","size":20693,"visible":true,"origin":"","legend":"\u003cp\u003eplot of Stern–Volmer equation relating F0(intensity with no quencher and F the fluorescence intensity with the quencher)\u003c/p\u003e","description":"","filename":"9.png","url":"https://assets-eu.researchsquare.com/files/rs-4572322/v1/477fc964af39f252b0774857.png"},{"id":60161156,"identity":"3315d8a6-c5e8-4bff-84f6-d5693c1895a8","added_by":"auto","created_at":"2024-07-12 13:05:05","extension":"png","order_by":10,"title":"Figure 10","display":"","copyAsset":false,"role":"figure","size":27788,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003elinear relation between the fluorescence quenching efficiency and the concentrations of Fe (III) in the range of 50–400 μM\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"10.png","url":"https://assets-eu.researchsquare.com/files/rs-4572322/v1/f0dd758c36b949805350b544.png"},{"id":60160503,"identity":"67a02ab4-ef4f-4243-984f-a3f9e77875cd","added_by":"auto","created_at":"2024-07-12 12:57:06","extension":"png","order_by":11,"title":"Figure 11","display":"","copyAsset":false,"role":"figure","size":236226,"visible":true,"origin":"","legend":"\u003cp\u003eemission fluorescence of the modified graphene quantum dots (GQD) both before and after the addition of a quencher\u003c/p\u003e","description":"","filename":"11.png","url":"https://assets-eu.researchsquare.com/files/rs-4572322/v1/76d8a05f00a20d64e6a772f3.png"},{"id":66096634,"identity":"e9e93689-5416-4b5b-b078-7e9ab7646712","added_by":"auto","created_at":"2024-10-07 16:01:51","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":3523295,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-4572322/v1/9b29d4a8-d182-4bfd-bd7a-bea1d55068d3.pdf"}],"financialInterests":"","formattedTitle":"Sensitive and selective fluorescent switch for Detection of Fe (III) Ion in Human urine Using luminol-functionalized Functionalized Graphene Quantum dots","fulltext":[{"header":"1. Introduction","content":"\u003cp\u003eDifferent diseases can cause a rise in the amount of iron excreted in the urine. (1) Hemolytic diseases: Individuals with substantial intravascular hemolysis, such as sickle cell anaemia, may experience elevated urine excretion of haemoglobin iron, reaching levels as high as 10.75 mg per 24 hours [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e, \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. Most iron expelled from the body is hemosiderin, and ferritin can also be found in the urine. Chronic kidney disease (CKD) is a medical condition characterized by long-term damage to the kidneys. Urine iron excretion in individuals with chronic kidney disease (CKD) is strongly linked to urine C-megalin. This marker indicates the metabolic burden on the proximal tubular epithelial cells (PTECs) in the remaining functional nephrons, mediated by megalin. Urine iron levels are linked to urine 8-OHdG, a sign of oxidative stress [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e] and iron excess [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. Consequently, our research, which aims to enhance the quality of human healthcare by quantifying Fe (III)ions, is of utmost importance. Graphene quantum dots (GQDs) have recently been identified as a promising platform for detecting Fe (III)ions due to their minimal toxicity, excellent water solubility, and ability to maintain their fluorescence under light exposure. [\u003cspan additionalcitationids=\"CR7 CR8 CR9 CR10\" citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e] Nevertheless, the GQDs demonstrate a low detection limit (LOD) for the Fe (III)ions due to the limited quantity of surface active sites.\u003c/p\u003e \u003cp\u003eNumerous studies have been conducted to improve the active sites on the GQDs and address these challenges. Functionalized graphene quantum dots (GQDs) containing amino groups, such as amine N, have several active sites contributing to their exceptional ability to detect Fe (III)ions. [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e] Furthermore, using a surfactant (such as PPy) for surface passivation led to the acquisition of GQDs with a narrower distribution and smaller size, ultimately resulting in an increased specific surface area. [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e] The detection performance for Fe (III)ions was improved because there are numerous active sites on the GQDs due to the increased specific surface area. Therefore, surface passivation and functionalization of GQDs with amine N groups can enhance the active sites, which can potentially play a crucial role in improving the Fe (III)detection limit. [\u003cspan additionalcitationids=\"CR15\" citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eThis study (illustrated in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e), is dedicated to developing a fluorescent material probe by functionalizing GQD with luminol. The probe has a remarkable ability to detect Fe(III). The modified graphene quantum dot (GQD) can be readily synthesized using a one-step hydrothermal synthesis method, with anhydrous citric acid as the precursor. The obtained Luminol-GQDs possess a consistent size and a graphene structure consisting of a single layer. Furthermore, Luminol-GQDs exhibit a vibrant light blue fluorescence. Adding Fe (III) ions will significantly reduce the fluorescence intensity of the Luminol-GQD. This assay offers a novel approach for detecting Fe (III)ions. Furthermore, the suitability of Luminol-GQDs was confirmed by performing a human urine analysis.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e"},{"header":"2. Experimental","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003e2.1. Materials\u003c/h2\u003e \u003cp\u003eAnhydrous citric acid (99.5-100.5%), sodium hydroxide (98%), 3-(trimethoxysilyl)propyl methacrylate (98%), luminol (97%), and Fe (III) chloride hexahydrate (97%) were all obtained from Sigma-Aldrich. Hydrochloric acid (35\u0026ndash;38%) was obtained from BDH, and artificial urine(from nanomer corporation) (pH\u0026thinsp;=\u0026thinsp;6.5) with analytical purity was used as received without any additional purification. All experiments were conducted using ultra-pure water with a resistivity of 18MΩ.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003e2.2. Instrumentation\u003c/h2\u003e \u003cp\u003eThe UV-1800 spectrophotometer (Shimadzu, Japan) was used to measure the ultraviolet-visible (UV-vis) absorption spectra. Fluorescence spectroscopy RF-5301PC (Shimadzu, Japan) was used to conduct steady-state fluorescence observations at room temperature. The GQDs were dissolved in water and transferred into a quartz cuvette with four polished windows. The excitation and emission monochromators were set to a slit-width of 5 nm. The ATR-FTIR spectra were acquired using a TENSOR 27 FT-IR spectrophotometer. Aeris-Benchtop X-ray Diffractometers (Malvern Panalytical) were used to conduct X-ray powder diffraction (XRD) patterns. The dimensions and structure of GQDs were analyzed using transmission electron microscopy (TEM) with a 100KV electron microscope, namely the Philips model CM120. SEM data were acquired using the Axia ChemiSEM instrument from the Netherlands.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003e2.3. Synthesis of GQDs\u003c/h2\u003e \u003cp\u003eThe GQDs were prepared by directly pyrolyzing citric acid. First, 1.92 g of anhydrous-citric acid was heated to 200\u0026deg;C using a hotplate. 5 minutes later, the citric acid was liquefied, and a color change was observed to be pale yellow and turn into a reddish-orange color collide of GQDs in 25 min. Notice that further heating times must avoided to prevent the formation of dark graphene oxide. The obtained reddish-orange liquid was added dropwise into 10 mg mL\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e NaOH (100 mL) under vigorous stirring for 10 min until thoroughly mixed. After mixing, the solution was neutralized by adding HCl drops (10 mg mL\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e) to obtain pH 7. As a result, a yellowish green GQDs solution was produced. The GQDs solution was filtered using a syringe filter (0.22\u0026micro;m pore size) twice to remove the residual reagents, and the obtained filtrate was then collected and dialyzed using a 1000Da dialysis bag for 8 hours. The resulting solution was then freeze-dried to obtain GQDs powder.[\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]. Synthesis of Luminol-GQDs 0.2 mL of 3 (Trimethoxysilyl)propyl methacrylate (TMPMS) was added to 100 mL of the GQDs solution and the mixture was stirred for 24 h at room temperature and was then freeze-dried to obtain mGQDs powder. Then, the luminol-modified GQDs were synthesized by adding 0.02 mg ml\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e of Luminol solution into 100 ml of 4 mg mL\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e NaOH solution For the synthesis of Luminol-GQDs, GQDs (2 mg ml\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e) and luminol were added to sodium hydroxide (4 mg ml\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e) followed by 30 min ultrasonic treatment. the resulting mixture was transferred into a polytetrafluoroethylene-lined autoclave and reacted at 180\u0026deg;C for 8 h. After cooling to room temperature, the product was filtered using a syringe filter with a 0.22\u0026micro;m pore size. Followed by freeze-drying to obtain luminol-GQD power.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec6\" class=\"Section2\"\u003e \u003ch2\u003e2.4. Detection procedure for Fe (III) ions\u003c/h2\u003e \u003cp\u003eStock standard solutions 2.7 mg ml\u003csup\u003e-1\u003c/sup\u003e Fe (III) were prepared by dissolving an appropriate amount of FeCl\u003csub\u003e3\u003c/sub\u003e.6H\u003csub\u003e2\u003c/sub\u003eO in artificial urine and adjusting the volume to 20 mL in a volumetric flask. It was further diluted to known concentrations using stepwise preparation. A fixed concentration of Luminol-GQDs was transferred to a fluorescent cuvette. The fluorescent intensity of the solution immediately was recorded from 367 to 600 nm with an excitation wavelength fixed at a wavelength that shows the highest intensity in 314 nanometers. After an appropriate amount of Fe (III) ions was added, the fluorescent intensity of the solution was again recorded. A similar procedure was performed for various pre-determined concentrations of Fe ions. For the sake of comparison, the volume of Luminol-GQDs solution was fixed to be 2 mL before the addition of Fe (III) All measurements were made at room temperature.\u003c/p\u003e \u003c/div\u003e"},{"header":"3. Results and discussion","content":"\u003cp\u003e\u003cstrong\u003e3.1 Morphological analysis and characterization\u0026nbsp;\u003c/strong\u003e\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;\u003c/p\u003e\n\u003cp\u003ePrior to its application as a fluorescent probe for Fe(III) detection, the synthesized modified GQD was subjected to characterization in order to verify its structural and optical features. Figure (2, a) displays the X-ray diffraction (XRD) patterns of graphene quantum dots (GQDs), revealing the presence of three distinct diffraction peaks. [17,18] The peak observed at an angle of 27.06 degrees (2\u0026theta;) corresponds to the crystallographic plane labeled as (002) in graphene. Additionally, there are other peaks present, The angles 2\u0026theta; = 31.3 and 45.1 degrees correspond to the crystallographic planes (100) and (102). The presence of three distinct diffraction peaks indicates a high level of sharpness, thereby confirming the excellent crystallinity of the produced GQDs (Fig. 2.b). Sherrer\u0026apos;s equation was utilized to estimate the average size, denoted as L, of the nanoparticles in the processed samples. Based on Scherrer\u0026apos;s equation, the grain size D may be estimated using the formula D = Klambda∕\u0026beta;cos\u0026theta;. In this equation, the constant K is equal to 0.942, the x-ray wavelength \u0026lambda; is 0.15405 nm, the diffraction peak half-height width \u0026beta; is 0.247, and the diffraction angle \u0026theta; is 13.4 degrees. Using these values, the calculated grain size D is 33.3 nm. However, in the case of a sample with a small particle size, the grain size determined by XRD is more than the actual size.\u003c/p\u003e\n\u003cp\u003eThe morphology and structure of GQD were examined using field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). Despite the challenge of obtaining high-quality TEM pictures due to the poor electro-contrast between the GQDs and the carbon-coated TEM grids, it is nevertheless possible to discern nanosheets measuring 20 nm in size (Fig. 3. c). This image displays graphene quantum dots (GQDs) with a diameter of around 20 nanometers and a spherical shape.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eField-emission scanning electron microscopy (FESEM) is a sophisticated imaging method that allows for the detailed examination of the surface structure and shape of graphene quantum dots (GQDs) with high precision. When GQDs are observed using FESEM (as shown in Fig. 3. a and b), they typically appear as a cluster of small, spherical particles with sizes ranging from a few nanometers. The particles\u0026apos; surface morphology and texture can vary based on the synthesis and processing method. The compositions and dispersion of the element were determined using EDX-mapping (Fig. 3. d,e, and f). The field emission scanning electron microscope (FE-SEM) reveals a detailed surface morphology, displaying the variations in surface texture of the created modified GQDs indicating the distribution of elements. The chemical composition of the modified GQDs was analyzed using energy dispersive X-ray (EDX) spectroscopy, and the corresponding results are presented in Fig. 2. g. Graphene quantum dots (GQDs) exhibit a consistent circular morphology.\u003c/p\u003e\n\u003cp\u003eThe Fourier-transform infrared (FT-IR) spectra of\u0026nbsp;graphene quantum dots\u0026nbsp;are presented in Fig. 4. a. The GQDs were functionalized using 3-(trimethoxysilyl)propyl methacrylate, resulting in broad absorption peaks at around 1376.20 cm\u0026minus;1 and 1550.49 cm\u003csup\u003e\u0026minus;1\u003c/sup\u003e. These peaks are attributed to the stretching vibrations of symmetric and asymmetric carboxyl groups, respectively. Additionally, a stretching vibration of C-OH was observed below 1350 cm\u003csup\u003e-1\u003c/sup\u003e, and broadband around 3347.19 cm\u003csup\u003e\u0026minus;1\u003c/sup\u003e was attributed to the stretching vibration of hydroxyl groups. [19]\u003c/p\u003e\n\u003cp\u003eIn Fig.4.b the use of luminol reveals the presence of C=O and asymmetric carboxyl group bonds at around 1571 and 1413 cm\u003csup\u003e-1\u003c/sup\u003e, respectively. Additionally, a large peak at 3500 cm\u003csup\u003e-1\u003c/sup\u003e indicates the stretching vibration of the N-H bond in luminol. The presence of a band at approximately 1413 cm\u003csup\u003e-1\u003c/sup\u003e can be attributed to the absorption of C\u0026ndash;N bonds. In contrast, a band at roughly 704 cm\u003csup\u003e-1\u003c/sup\u003e is associated with the out-of-plane bending of C-H aromatic bonds. Identifying a peak at 3100 cm\u003csup\u003e-1\u003c/sup\u003e indicated the presence of N\u0026ndash;H stretching vibration in the amine groups, confirming the successful integration of nitrogen atoms.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e3.2 Optical properties\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eFigure 5 depicts the UV-Vis absorption spectra of the modified graphene quantum dots (GQDs) samples. The GQDs display a weak peak at 360 nm due to the n-\u0026pi;* transition in C=O groups, an identifiable band for the modified GQDs.\u003c/p\u003e\n\u003cp\u003eThe fluorescence spectra in Fig.6 indicate that the highest fluorescence emission of GQDs occurred at wavelengths 465 nm while blue shifting with 428 nm maximum wavelength in the luminol-GQD was noticed due to fractionalization, respectively. The Luminol-GQD produced in its original form demonstrates a high level of fluorescence emission and possesses surface functionalization that is distinctive to nitrogen. The hydrophilicity of the GQDs, which is responsible for their high solubility in water, is a result of the presence of these functional groups. Due to the existence of these functional groups and intense emission, these Luminol-GQDs are anticipated to be an optimal choice for fluorescence sensing.\u003c/p\u003e\n\u003cp\u003eThe relationship between the emission wavelength and the excitation has been investigated, and Figure 7 displays the fluorescence spectra of the Luminol-GQDs solution at different excitation wavelengths. The Figure demonstrates that the emission maximum wavelength remains constant regardless of the selected excitation wavelength. The emission of graphene quantum dots is unaffected by excitation, indicating that the size and surface state of the sp2 clusters within GQDs are uniform.\u003c/p\u003e\n\u003cp\u003e\u003cspan dir=\"RTL\"\u003e\u0026nbsp;3.3\u0026nbsp;\u003c/span\u003e\u003cstrong\u003eSelective detection of Fe (III)ion\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eSynthetic urine has been proven to exhibit a significant matrix profile when analyzed using various analytical methods. Fluorescence spectrophotometry limits the matrix effect by utilizing the selectivity of fluorescence for certain molecules that impact the analysis. Monitoring the effect of the matrix by detecting Fe(III) ions in artificial urine before analyzing real human urine was first tested. To achieve this goal, the selective sensing of Fe(III) was carried out using excitation/emission wavelengths of 314/428 nm and a pH of 7.4 in a phosphate buffer saline solution containing Luminol-GQDs using Synthetic urine as the solution media, with a concentration of 0.0819 g in 40 ml of GQD. The excitation wavelength of 314 nm was chosen as it resulted in the strongest fluorescence emission. Thus, this specific wavelength was chosen to observe and measure the impact of Fe(III) ions on fluorescence intensity. \u0026nbsp;The fluorescence intensities of Luminol-GQD were measured upon introducing different concentrations of ferric ions (Fig. 8). The results indicate that Luminol-GQD has a strong ability to detect Fe (III) specifically. The process of fluorescence quenching is associated with the high attraction of Fe (III) ions to the amino group of Luminol-GQD, resulting in the formation of a stable complex. \u003cspan dir=\"RTL\"\u003eT\u003c/span\u003eo elucidate the potential mechanism of our detecting system, an\u0026nbsp;endeavor\u0026nbsp;to establish a correlation between the concentration of Fe (III) ions and the luminescence intensity of Luminol-GQDs was done\u0026nbsp;by employing the Stern-Volmer relationship. Fig. 9 depicts the Stern-Volmer analysis of the quenching experiment. Specifically, the ratio of initial fluorescence intensity to the fluorescence intensity after quenching (F0/F), plotted against the concentration of Fe(III). The linear relationship of the Stern-Volmer Plot over the concentration range of Fe (III) ions from 50 to 300 \u0026mu;M is notable. This behavior indicates that a statistic mechanism involving charge transfer likely controls the interaction between GQDs and Fe(III)\u0026nbsp;ions\u003c/p\u003e\n\u003cp\u003eThe regression value (R\u003csup\u003e2\u003c/sup\u003e) was found to be 0.9901 which reflects a linear relation between the quencher concentration and fluorescence intensity, the obtained R\u003csup\u003e2\u003c/sup\u003e value indicates a linear relation between the quencher concentration and fluorescence intensity. The findings indicate that the produced Luminol-GQD can be a selective and sensitive sensor for detecting Fe(III) ions in artificial urine. The formulas for determining the limit of detection (LOD, equation 1) and limit of quantification (LOQ, equation 2) are below An abrupt decrease in photoluminescence (PL) was seen upon introducing Fe(III). The fluorescence quenching was examined at Fe(III) concentrations ranging from 1 to 300 \u0026mu;M. A valid linear correlation was observed, as shown in Fig. 10, demonstrating a strong linear association.\u003c/p\u003e\n\u003cp\u003eLOD = 3.3* \u0026sigma; /S\u003c/p\u003e\n\u003cp\u003eLOQ = 10 * \u0026sigma; /S\u003c/p\u003e\n\u003cp\u003ewhere \u0026sigma; is the standard deviation of the intercept and S is the slope of the linear regression plot. The LOD and LOQ were calculated to be 1.5 \u0026mu;M and 5.2 \u0026mu;M, respectively. The detection limit of Fe (III)found in this study was much lower than the reported studies in Table 1\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 1\u003c/strong\u003e. Comparison of Fe (III) Sensing Properties of the Luminol-GQD with Those of Recently Reported GQDs\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\" width=\"642\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd width=\"25.077881619937695%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003ematerials\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"39.09657320872274%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003etechnique in detail\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"12.461059190031152%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003edetection limit (\u0026mu;M)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"12.149532710280374%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eAnalysis time\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"11.214953271028037%\" valign=\"top\"\u003e\n \u003cp\u003e\u003cstrong\u003eref\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"25.077881619937695%\" valign=\"top\"\u003e\n \u003cp\u003eLuminol-GQD\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"39.09657320872274%\"\u003e\n \u003cp\u003ehydrothermal method\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"12.461059190031152%\"\u003e\n \u003cp\u003e1.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"12.149532710280374%\"\u003e\n \u003cp\u003e\u0026lt; 3 min\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"11.214953271028037%\" valign=\"top\"\u003e\n \u003cp\u003eThis work\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"25.077881619937695%\" valign=\"top\"\u003e\n \u003cp\u003eGQDs\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"39.09657320872274%\"\u003e\n \u003cp\u003ehydrothermal/ modified hummer\u0026rsquo;s method\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"12.461059190031152%\"\u003e\n \u003cp\u003e1.1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"12.149532710280374%\"\u003e\n \u003cp\u003e\u0026gt;24h\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"11.214953271028037%\" valign=\"top\"\u003e\n \u003cp\u003e20\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"25.077881619937695%\" valign=\"top\"\u003e\n \u003cp\u003eN-doped GQDs\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"39.09657320872274%\"\u003e\n \u003cp\u003eammonia through hydrothermal method\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"12.461059190031152%\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"12.149532710280374%\"\u003e\n \u003cp\u003e\u0026gt;24\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"11.214953271028037%\" valign=\"top\"\u003e\n \u003cp\u003e21\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"25.077881619937695%\" valign=\"top\"\u003e\n \u003cp\u003eGQDs\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"39.09657320872274%\"\u003e\n \u003cp\u003echemical oxidation\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"12.461059190031152%\"\u003e\n \u003cp\u003e60\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"12.149532710280374%\"\u003e\n \u003cp\u003e\u0026gt;26h\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"11.214953271028037%\" valign=\"top\"\u003e\n \u003cp\u003e22\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"25.077881619937695%\" valign=\"top\"\u003e\n \u003cp\u003eN-doped GQDs\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"39.09657320872274%\"\u003e\n \u003cp\u003emicrowave synthesis\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"12.461059190031152%\"\u003e\n \u003cp\u003e100\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"12.149532710280374%\"\u003e\n \u003cp\u003e\u0026gt;27h\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"11.214953271028037%\" valign=\"top\"\u003e\n \u003cp\u003e23\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"25.077881619937695%\" valign=\"top\"\u003e\n \u003cp\u003eGQDs\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"39.09657320872274%\"\u003e\n \u003cp\u003eelectrochemical synthesis\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"12.461059190031152%\"\u003e\n \u003cp\u003e7.22\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"12.149532710280374%\"\u003e\n \u003cp\u003e--\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"11.214953271028037%\" valign=\"top\"\u003e\n \u003cp\u003e24\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"25.077881619937695%\" valign=\"top\"\u003e\n \u003cp\u003eGraphitic GQDs\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"39.09657320872274%\"\u003e\n \u003cp\u003eelectrochemical synthesis\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"12.461059190031152%\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"12.149532710280374%\"\u003e\n \u003cp\u003e\u0026gt;96 h\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"11.214953271028037%\" valign=\"top\"\u003e\n \u003cp\u003e25\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"25.077881619937695%\" valign=\"top\"\u003e\n \u003cp\u003eN-doped/amino GQDs\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"39.09657320872274%\"\u003e\n \u003cp\u003echemical oxidation\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"12.461059190031152%\"\u003e\n \u003cp\u003e0.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"12.149532710280374%\"\u003e\n \u003cp\u003e\u0026gt;24\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"11.214953271028037%\" valign=\"top\"\u003e\n \u003cp\u003e26\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"25.077881619937695%\" valign=\"top\"\u003e\n \u003cp\u003eN-doped GQDs\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"39.09657320872274%\"\u003e\n \u003cp\u003ehydrothermal method\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"12.461059190031152%\"\u003e\n \u003cp\u003e0.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"12.149532710280374%\"\u003e\n \u003cp\u003e\u0026gt;12 h\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"11.214953271028037%\" valign=\"top\"\u003e\n \u003cp\u003e27\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e3.4 Analysis of Fe (III)in human urine sample\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe fluorescence sensor was utilized to detect Fe(III) ions in real human urine samples, demonstrating the capabilities of the probe. Healthy volunteers provided human urine samples, which were collected following the international standard for manual urine collection. The urine liquid was either analyzed immediately or held at a temperature of -20\u0026deg;C until it could be analyzed. Prior to the analysis, the urine samples were spiked with\u0026nbsp;varying quantities of Fe(III). In order to assess the repeatability of the suggested approach (e.g., precision), each sample was analyzed five times using the same working conditions within a single day. Fig. 11. Display the emission fluorescence of the modified graphene quantum dots (GQD) both before and after the addition of a quencher.\u003cbr\u003e\u0026nbsp;The implemented technique achieves a 94.75% recovery of Fe(III) ions in urine samples, with a Relative Standard Deviation (RSD) of 4.12%. This demonstrates the practicality of the suggested method for directly analyzing Fe(III) in human urine without the need for dilution or pre-treatment.\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eA novel technique has been developed to rapidly and easily analyze Fe(III) ions in human urine with remarkable selectivity. This study utilized room temperature fluorescence to monitor the quenching signal caused by Fe(III) ions, enabling a direct detection of Fe(III) ions. This study represents the first report (to the best of our knowledge) on utilizing Luminol-GQD as a sensor for detecting Fe(III) ions in human urine. The findings of our study demonstrate that this approach exhibits a high level of recovery, a remarkably short period for analysis, and a distinct linear relationship within the chosen concentration range.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eOn behalf of all authors, the corresponding author states that there is no conflict of interest.\u003c/strong\u003e\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n \u003cli\u003e\u003cstrong\u003eYao, Q., et al.,\u003c/strong\u003e\u003cem\u003eOne-pot synthesis of fluorescent nitrogen-doped graphene quantum dots for portable detection of iron ion.\u003c/em\u003e Current Applied Physics, 2022. \u003cstrong\u003e41\u003c/strong\u003e: p. 191-199.\u003c/li\u003e\n \u003cli\u003e\u003cstrong\u003eSreeja, K., et al.,\u003c/strong\u003e\u003cem\u003eFluorine-rich graphene quantum dots by selective oxidative cutting of hydroxy fluorographene and their application for sensing of Fe (III) ions.\u003c/em\u003e Journal of Fluorine Chemistry, 2023. \u003cstrong\u003e268\u003c/strong\u003e: p. 110130.\u003c/li\u003e\n \u003cli\u003e\u003cstrong\u003eSEARS, D.A., et al.,\u0026nbsp;\u003c/strong\u003e\u003cem\u003eUrinary iron excretion and renal metabolism of hemoglobin in hemolytic diseases.\u003c/em\u003e Blood, 1966. \u003cstrong\u003e28\u003c/strong\u003e(5): p. 708-725.\u003c/li\u003e\n \u003cli\u003e\u003cstrong\u003eWashington, R. and D.R. Boggs,\u003c/strong\u003e\u003cem\u003eUrinary iron in patients with sickle cell anemia.\u003c/em\u003e The Journal of Laboratory and Clinical Medicine, 1975. \u003cstrong\u003e86\u003c/strong\u003e(1): p. 17-23.\u003c/li\u003e\n \u003cli\u003e\u003cstrong\u003eNakatani, S., et al.,\u0026nbsp;\u003c/strong\u003e\u003cem\u003eUrinary iron excretion is associated with urinary full-length megalin and renal oxidative stress in chronic kidney disease.\u003c/em\u003e Kidney and Blood Pressure Research, 2018. \u003cstrong\u003e43\u003c/strong\u003e(2): p. 458-470.\u003c/li\u003e\n \u003cli\u003e\u003cstrong\u003eYoo, D., et al.,\u0026nbsp;\u003c/strong\u003e\u003cem\u003eCarbon dots as an effective fluorescent sensing platform for metal ion detection.\u003c/em\u003e Nanoscale research letters, 2019. \u003cstrong\u003e14\u003c/strong\u003e: p. 1-13.\u003c/li\u003e\n \u003cli\u003e\u003cstrong\u003eZhu, S., et al.,\u003c/strong\u003e\u003cem\u003eHighly photoluminescent carbon dots for multicolor patterning, sensors, and bioimaging.\u003c/em\u003e Angewandte Chemie International Edition, 2013. \u003cstrong\u003e52\u003c/strong\u003e(14): p. 3953-3957.\u003c/li\u003e\n \u003cli\u003e\u003cstrong\u003eMohammed, L.J. and K.M. Omer,\u0026nbsp;\u003c/strong\u003e\u003cem\u003eCarbon dots as new generation materials for nanothermometer.\u003c/em\u003e Nanoscale Research Letters, 2020. \u003cstrong\u003e15\u003c/strong\u003e(1): p. 182.\u003c/li\u003e\n \u003cli\u003e\u003cstrong\u003eMohammed, L.J. and K.M. Omer,\u003c/strong\u003e\u003cem\u003eDual functional highly luminescence B, N Co-doped carbon nanodots as nanothermometer and Fe3+/Fe2+ sensor.\u003c/em\u003e Scientific reports, 2020. \u003cstrong\u003e10\u003c/strong\u003e(1): p. 3028.\u003c/li\u003e\n \u003cli\u003e\u003cstrong\u003eOmer, K.M. and M. Sartin,\u003c/strong\u003e\u003cem\u003eDual-mode colorimetric and fluorometric probe for ferric ion detection using N-doped carbon dots prepared via hydrothermal synthesis followed by microwave irradiation.\u003c/em\u003e Optical Materials, 2019. \u003cstrong\u003e94\u003c/strong\u003e: p. 330-336.\u003c/li\u003e\n \u003cli\u003e\u003cstrong\u003eAnanthanarayanan, A., et al.,\u003c/strong\u003e\u003cem\u003eFacile synthesis of graphene quantum dots from 3D graphene and their application for Fe3+ sensing.\u003c/em\u003e Advanced Functional Materials, 2014. \u003cstrong\u003e24\u003c/strong\u003e(20): p. 3021-3026.\u003c/li\u003e\n \u003cli\u003e\u003cstrong\u003eLi, L., et al.,\u003c/strong\u003e\u003cem\u003eSynthesis of nitrogen-doped and amino acid-functionalized graphene quantum dots from glycine, and their application to the fluorometric determination of ferric ion.\u003c/em\u003e Microchimica Acta, 2015. \u003cstrong\u003e182\u003c/strong\u003e: p. 763-770.\u003c/li\u003e\n \u003cli\u003e\u003cstrong\u003eTajik, S., et al.,\u003c/strong\u003e\u003cem\u003eCarbon and graphene quantum dots: A review on syntheses, characterization, biological and sensing applications for neurotransmitter determination.\u003c/em\u003e RSC advances, 2020. \u003cstrong\u003e10\u003c/strong\u003e(26): p. 15406-15429.\u003c/li\u003e\n \u003cli\u003e\u003cstrong\u003eMansuriya, B.D. and Z. Altintas,\u003c/strong\u003e\u003cem\u003eApplications of graphene quantum dots in biomedical sensors.\u003c/em\u003e Sensors, 2020. \u003cstrong\u003e20\u003c/strong\u003e(4): p. 1072.\u003c/li\u003e\n \u003cli\u003e\u003cstrong\u003ePeng, J., et al.,\u0026nbsp;\u003c/strong\u003e\u003cem\u003eGraphene quantum dots derived from carbon fibers.\u003c/em\u003e Nano letters, 2012. \u003cstrong\u003e12\u003c/strong\u003e(2): p. 844-849.\u003c/li\u003e\n \u003cli\u003e\u003cstrong\u003ePan, D., et al.,\u003c/strong\u003e\u003cem\u003eHydrothermal route for cutting graphene sheets into blue‐luminescent graphene quantum dots.\u003c/em\u003e Advanced materials, 2010. \u003cstrong\u003e22\u003c/strong\u003e(6): p. 734-738.\u003c/li\u003e\n \u003cli\u003e\u003cstrong\u003eXu, C., et al.,\u0026nbsp;\u003c/strong\u003e\u003cem\u003eEffects of different pyrolysis preparation condition on the fluorescence properties of graphene quantum dots.\u003c/em\u003e Optical Engineering, 2021. \u003cstrong\u003e60\u003c/strong\u003e(11): p. 117103-117103.\u003c/li\u003e\n \u003cli\u003e\u003cstrong\u003eMaiti, S., et al.,\u0026nbsp;\u003c/strong\u003e\u003cem\u003eSynthesis of excitation independent highly luminescent graphene quantum dots through perchloric acid oxidation.\u003c/em\u003e Langmuir, 2017. \u003cstrong\u003e33\u003c/strong\u003e(51): p. 14634-14642.\u003c/li\u003e\n \u003cli\u003e\u003cstrong\u003eMasteri-Farahani, M., S. Mashhadi-Ramezani, and N. Mosleh,\u0026nbsp;\u003c/strong\u003e\u003cem\u003eMolecularly imprinted polymer containing fluorescent graphene quantum dots as a new fluorescent nanosensor for detection of methamphetamine.\u003c/em\u003e Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2020. \u003cstrong\u003e229\u003c/strong\u003e: p. 118021.\u003c/li\u003e\n \u003cli\u003e\u003cstrong\u003eAbbas, A., L.T. Mariana, and A.N. Phan,\u003c/strong\u003e\u003cem\u003eBiomass-waste derived graphene quantum dots and their applications.\u003c/em\u003e Carbon, 2018. \u003cstrong\u003e140\u003c/strong\u003e: p. 77-99.\u003c/li\u003e\n \u003cli\u003eLiu, H.; Na, W.; Liu, Z.; Chen, X.; Su, X. A novel turn-on fluorescent strategy for sensing ascorbic acid using graphene quantum dots as fluorescent probe. Biosens Bioelectron. 2017, 92, 229\u0026minus;233.\u003c/li\u003e\n \u003cli\u003eVan Tam, T.; Trung, N. B.; Kim, H. R.; et al. One-pot synthesis of N-doped graphene quantum dots as a fluorescent sensing platform for Fe3+ ions detection. Sens. Actuators, B 2014, 202, 568\u0026minus;793.\u003c/li\u003e\n \u003cli\u003eZhu, X.; Zhang, Z.; Xue, Z.; Huang, C.; Shan, Y.; Liu, C.; Qin, X.; Yang, W.; Chen, X.; Wang, T. Understanding the selective detection of Fe3+ based on graphene quantum dots as fluorescent probes: The Ksp of a Metal hydroxide Assisted mechanism. Anal. Chem. 2017, 89, 12054\u0026minus;12058.\u003c/li\u003e\n \u003cli\u003eRen, Q.; Ga, L.; Ai, J. Rapid Synthesis of Highly Fluorescent Nitrogen-Doped graphene quantum dots for effective detection of ferric ions and as fluorescent ink. ACS Omega 2019, 4, 15842\u0026minus;15848.\u003c/li\u003e\n \u003cli\u003eAnanthanarayanan, A.; Wang, X.; Routh, P.; Sana, B.; Lim, S.; Kim, D. H.; Lim, K. H.; Li, J.; Chen, P. Facile Synthesis of graphene quantum dots from 3D graphene their applications for Fe3+ sensing. Adv. Funct. Mater. 2014, 24, 3021\u0026minus;3026.\u003c/li\u003e\n \u003cli\u003eZhang, Y. L.; Wang, L.; Zhang, H. C.; Liu, Y.; Wang, H. Y.; Kang, Z. H.; Lee, S. T. Graphitic carbon quantum dots as a fluorescent sensing platform for highly efficient detection of Fe3+ ions. RSC Adv. 2013, 3, 3733\u0026minus;3738.\u003c/li\u003e\n \u003cli\u003eXu, H.; Zhou, S.; Liu, J.; Wei, Y. Nanospace-confined preparation of uniform nitrogen-doped graphene quantum dots for highly selective fluorescence dual-functional determination of Fe3+ and ascorbic acid. RSC Adv. 2018, 8, 5500\u0026minus;5508.\u003c/li\u003e\n\u003c/ol\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":true,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"chemical-papers","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"chpa","sideBox":"Learn more about [Chemical Papers](http://link.springer.com/journal/11696)","snPcode":"11696","submissionUrl":"https://www.editorialmanager.com/CHPA/default.aspx","title":"Chemical Papers","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"Luminol-mGQDs , Nanosensor , Fe+3 detection , Fluorescent assay","lastPublishedDoi":"10.21203/rs.3.rs-4572322/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-4572322/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eA fluorescent switch based on graphene quantum dots (GQDs) has been synthesized and modified using Luminol to detect Fe (III) in human urine selectively. The pyrolysis of anhydrous citric acids produced GQDs abundant in amino groups. The luminol modification shows distinct optical characteristics, improving the fluorescence intensity by approximately 6.41 times compared to GQD alone. The probe employs static quenching to initiate the fluorescence response by utilizing the interaction between Fe (III) and Luminol-GQDs, resulting in the suppression of fluorescence. The probe is capable of detecting Fe (III) in both a pure aqueous solution and synthetic urine. Furthermore, it is also able to detect Fe (III) in human urine. The concentration of Fe (III) required to quench the fluorescence intensity of Luminol-GQDs exhibits a strong linear relationship. A good linear relationship was obtained for Fe (III) concentrations ranging from 50 to 400 \u0026micro;M. Notably, this sensitivity surpasses that of earlier studies. The detection limit of Fe (III) using Luminol-GQDs is approximately 1.5 \u0026micro;M. The real sample detection was conducted using a human urine sample, and satisfactory recoveries of approximately 94.57% were achieved.\u003c/p\u003e","manuscriptTitle":"Sensitive and selective fluorescent switch for Detection of Fe (III) Ion in Human urine Using luminol-functionalized Functionalized Graphene Quantum dots","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-07-12 12:49:00","doi":"10.21203/rs.3.rs-4572322/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"reviewerAgreed","content":"","date":"2024-06-22T15:20:30+00:00","index":0,"fulltext":""},{"type":"reviewersInvited","content":"","date":"2024-06-22T15:16:50+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"Chemical Papers","date":"2024-06-22T12:16:41+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2024-06-15T11:55:48+00:00","index":"","fulltext":""},{"type":"submitted","content":"Chemical Papers","date":"2024-06-13T15:32:31+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"chemical-papers","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"chpa","sideBox":"Learn more about [Chemical Papers](http://link.springer.com/journal/11696)","snPcode":"11696","submissionUrl":"https://www.editorialmanager.com/CHPA/default.aspx","title":"Chemical Papers","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"d1db8206-ad88-4d4e-958a-b709f408b7d4","owner":[],"postedDate":"July 12th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2024-10-07T15:58:42+00:00","versionOfRecord":{"articleIdentity":"rs-4572322","link":"https://doi.org/10.1007/s11696-024-03705-x","journal":{"identity":"chemical-papers","isVorOnly":false,"title":"Chemical Papers"},"publishedOn":"2024-09-30 15:56:51","publishedOnDateReadable":"September 30th, 2024"},"versionCreatedAt":"2024-07-12 12:49:00","video":"","vorDoi":"10.1007/s11696-024-03705-x","vorDoiUrl":"https://doi.org/10.1007/s11696-024-03705-x","workflowStages":[]},"version":"v1","identity":"rs-4572322","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-4572322","identity":"rs-4572322","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}