A sensitive electrochemical DNA biosensor for determination of Capecitabine anticancer drug based on ss-DNA/RGO/MoS2/CPE electrode

A sensitive electrochemical DNA biosensor for determination of Capecitabine anticancer drug based on ss-DNA/RGO/MoS2/CPE electrode | 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 A sensitive electrochemical DNA biosensor for determination of Capecitabine anticancer drug based on ss-DNA/RGO/MoS2/CPE electrode Masoumeh Mohammadi, Amirabbas Rafati This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-4006078/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract The present research utilized a simplified procedure for developing a novel electrochemical sensor based on a carbon paste electrode (CPE) modified with single-stranded DNA (ss-DNA), reduced graphene oxide and molybdenum disulfide. Unmodified (bare CPE) and modified (ss-DNA/RGO/MoS 2 /CPE) electrodes were characterized by scanning electron microscopy (SEM), EDX analysis and cyclic voltammetry (CV). Characterization data confirm the good conductivity and electrocatalytic nature with more electrochemically active sites in ss-DNA/RGO/MoS 2 /CPE compared to bare CPE in determination of capecitabine (CAP) analysis in real samples. Two linear ranges have been obtained for the CAP concentration within the ranges of 0.01-10 µM with and 10–60 µM, with a detection limit of 0.0108 µM and limit of quantification of 0.036 µM. Lower linear concentration range, 0.01-10 µM showed sensitivity of 276.85 AM − 1 cm − 2 , and another from 10 µM to 60 µM with a sensitivity of 5.88 AM − 1 cm − 2 . The performance of the modified electrode was tested in human serum samples and obtained satisfactory recovery results. The selectivity and practical ability of ss-DNA/RGO/MoS 2 /CPE to determine CAP in the presence of different interfering species were investigated. The results show the selective, reliable and accurate response of ss-DNA/RGO/MoS 2 /CPE as CAP electrochemical sensor. Capecitabine Single stranded DNA DNA biosensor Carbon paste electrode Voltammetry Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 1. Introduction Cancer remains one of the most formidable challenges to global public health, necessitating continuous advancements in diagnostic and therapeutic strategies [ 1 – 5 ]. CAP (scheme 1 ), a prodrug used in the treatment of various cancers, exemplifies the importance of precise monitoring to ensure optimal therapeutic outcomes while minimizing potential side effects [ 6 – 8 ]. Electrochemical methods offer distinct advantages over other techniques for the determination of drug compounds, showcasing their applicability and efficiency in pharmaceutical analysis. One primary advantage lies in their high sensitivity, allowing for the detection of low concentrations of drugs, even in complex matrices. Additionally, electrochemical methods often exhibit excellent selectivity, minimizing interference from coexisting substances and enhancing the accuracy of drug quantification. The real-time monitoring capabilities of electrochemical techniques enable dynamic studies of drug behavior and kinetics, providing valuable insights into their electroactive properties. Moreover, these methods are inherently cost-effective, as they generally require simpler instrumentation and offer a rapid analysis turnaround. Overall, the versatility, sensitivity, selectivity, and cost-effectiveness of electrochemical methods position them as powerful tools for drug determination, contributing significantly to advancements in pharmaceutical research and development [ 9 – 13 ]. Among the electrochemical methods, electrochemical sensor and biosensors possess several advantages including high sensitivity and selectivity, rapid response time, miniaturization and portability, low cost and simple instrumentation, operational versatility, real-time monitoring and continuous measurement, wide range of applicability, ease of functionalization [ 14 – 23 ]. These advantages collectively make electrochemical sensors powerful tools for monitoring and quantifying various analytes in a wide range of fields, contributing to their widespread use and ongoing research and development In recent years, electrochemical DNA biosensors have gained prominence in recent years due to their high sensitivity, rapid response, and specificity in detecting target molecules [ 24 – 28 ]. The integration of advanced nanomaterials further enhances the performance of these biosensors, offering improved electrocatalytic properties and a larger surface area for enhanced biomolecular interactions [ 29 ]. In this context, the development of sensitive and reliable biosensors for the detection of anticancer drugs has emerged as a crucial area of research. It is based on a novel electrochemical DNA biosensor designed for the specific determination of CAP, a widely utilized chemotherapeutic agent. The biosensor is constructed using a hybrid nanomaterial platform comprising reduced graphene oxide (RGO), molybdenum disulfide (MoS 2 ), and a carbon paste electrode [ 30 ]. The synergistic effects of these materials contribute to the enhanced electrochemical performance of the biosensor, facilitating the sensitive and selective detection of CAP in complex biological matrices. The rational design and fabrication of the RGO/MoS 2 /carbon paste electrode aim to overcome challenges associated with the detection of CAP, such as low concentrations and potential interference from other biomolecules [ 31 ]. The utilization of DNA as a recognition element adds an additional layer of specificity, enabling the biosensor to discriminate CAP from structurally similar compounds [ 32 ]. 2. Experimental 2.1 Reagents and Apparatus CAP drug was acquired from Sobhan Oncology Company (Iran). Ascorbic acid (AA), uric acid (UA), folic acid (AF), and highly pure paraffin were procured from Sigma-Aldrich Chemical Co. Graphite powder was obtained from Sinchem, Korea. 2.2. Synthesis of Graphene Oxide Graphene oxide was prepared from natural graphite using the well-known Hummers method [ 33 ]. In a typical synthesis process, 2 g of graphite powder was added to 46 ml concentrated H 2 SO 4 at 0°C, followed by the gradual addition of 6 g KMnO 4 under magnetic stirring at 15°C. The mixture was stirred at 35°C for 40 min, with the temperature slowly increasing to 40°C. Simultaneously, 100 ml of distilled water was added slowly, maintaining the temperature for 30 min under reflux conditions. After the reaction, 300 ml of distilled water followed by 20 ml of 30% H 2 O 2 solution was added, resulting in a golden solution. The solid product was separated by centrifugation, washed with 10% HCl solution, and water. The final product was dried in a vacuum oven at 60°C overnight, yielding lamellar solids for subsequent experiments. 2.3. Preparation of Reduced Graphene Oxide (RGO) by Hydrothermal Method Initially, 1 g of as-synthesized graphene oxide (GO) was suspended in 100 ml ethanol through 100 minutes of sonication, yielding a brown colloidal solution. Subsequently, the solution was sealed in a 50 mL Teflon-lined autoclave and maintained at a temperature of 200°C for 20 hours. The solids were filtered, washed with acetone and distilled water, and then dried in a vacuum oven at 70°C overnight. The obtained solid was dissolved in 100 ml of chloroform for 30 minutes under ultrasonication, followed by centrifugation. The resulting solid was dried and analyzed. All other chemical reagents were of analytical grade and used without further purification. All aqueous solutions were prepared with deionized water. Human blood serum samples devoid of CAP were obtained from the Central Hamedan Clinical and Pathological Laboratory (Hamedan, Iran) and stored in a refrigerator immediately after collection before use. 2.4. Synthesis of MoS 2 by Hydrothermal Method MoS 2 materials with different morphologies were synthesized via a simple hydrothermal method under acidic conditions using Sodium molybdate (Na 2 MoO 4 ·2H 2 O), Thiourea (CH 4 N 2 S), and Polyethylene glycol (PEG) as starting materials. In a typical preparation process, 1.21 g Na 2 MoO 4 ·2H 2 O (0.005 mol), 1.56 g CH 4 N 2 S (0.02 mol), and 0.14 g PEG were dissolved in 30 mL of deionized water and sonicated for 30 minutes. The mixed solution was transferred into a 50 mL Teflon-lined stainless-steel autoclave for hydrothermal treatment at 200°C for 48 hours and cooled to room temperature naturally. MoS 2 in the form of black powder was obtained by centrifugation at 4000 rpm for 10 minutes, washed with deionized water and ethanol, and dried in the vacuum oven at 60°C for 12 hours. The obtained MoS 2 product was analyzed. Phosphoric acid (1.67 g/L) (Merck, Germany) and sodium hydroxide (Merck, Germany) solutions were used to prepare buffer solutions. The pH values of the buffer solutions were measured with a pH meter (Metrohm 744) with an accuracy of ± 0.01 units. The stock solution (0.3 ppm ss-DNA) was prepared using Phosphate buffer solution and preserved in the freezer. Diluted solutions of DNA were prepared using Phosphate buffer solution. All voltammetric measurements were carried out using a µ-autolab modular electrochemical system (PGSTAT101, Metrohm, Netherlands), and NOVA 1.7 software was applied for data recording. All electrochemical experiments were conducted at room temperature using a conventional 25 mL three-electrode glass cell containing an Ag/AgCl reference electrode, a platinum plate counter electrode, and a modified carbon paste electrode (CPE) as the working electrode. Scanning electron microscopy (SEM) (Model Quanta 250 Field Emission Gun) coupled with energy dispersive analysis of X-ray (EDX) Unit (FEI Company, USA) were used for the analysis of the electrode surface morphology and compositions. 2.5. Preparation of ss-DNA/ MoS 2 /RGO/CPE Electrode The modified CPEs were prepared by hand mixing a mixture of graphite powder, RGO, MoS 2 , ss-DNA and paraffin oil with various ratios (w/w) presented in Table I in a mortar for at least 40 minutes. The modified carbon paste was packed into the tip of a 1 mL insulin plastic syringe, and a copper wire was inserted to obtain external electric contact. The electrode surface was polished with a piece of soft paper to prepare the electrode. A new surface was obtained by cutting the end of the tube and rinsed carefully with deionized water before each measurement. Electrochemical parameters of CPEs were obtained with voltammetric measurement analysis in a 5.0 mM K 3 [Fe(CN) 6 ] solution. The prepared MoS 2 /RGO/CPE was thoroughly washed with deionized water and dried before use. Then, a droplet of 10 µL of 0.3 g/mL ss-DNA solution in phosphate buffer was dropped onto the surface of the MoS 2 /RGO/CPE and incubated for 24 hours at 4°C before use. 3. Results and Discussion 3.1. Surface Characterization of Modified Electrode To investigate the surface morphology and the modifying effect of RGO and MoS 2 on the CPE, SEM images were captured before and after electrode modification. Figures 1 a, 1 b, and 1 c present SEM images of the composite RGO/MoS 2 /CPE, revealing MoS 2 dispersed on the surface of RGO and the graphite matrix. The presence of RGO and MoS 2 significantly increased the surface area and porosity of the electrode, enhancing the efficiency of the modified electrode. The EDX spectrum in Fig. 2 confirms that the carbon paste electrode modified with RGO and MoS 2 is suitable for electrocatalysis. 3.2. Electrochemical Characterization of Modified Electrodes Cyclic voltammetry (CV) was employed to characterize both modified and bare electrodes using a 5.0 mM K 3 Fe(CN) 6 probe. Figure 3 illustrates the cyclic voltammograms of CPE, RGO/CPE, MoS 2 /RGO/CPE, and ss-DNA/MoS 2 /RGO/CPE in the potential range of -0.2 V to + 1.0 V. The electrode response improved upon adding RGO and MoS 2 to the carbon paste electrode materials. The increased current peaks for modified electrodes can be attributed to the enhanced electron transfer rate and increased active surface sites due to the modification. Additionally, the active surface area of the electrodes was determined using the [Fe(CN) 6 ] 3−/4− redox system at different potential scan rates. The Randles–Sevĉik equation (Eq. 1) for a reversible process was applied, and the calculated active surface areas for each electrode are tabulated in Table II. I pa = 2.69 × 10 5 n 3 A \({ D}_{R}^{1/2}{\nu }^{1/2}{\text{C}}_{0}\) (1) where n is the number of transferred electrons in the oxidation and reduction process of ferrocyanide, C 0 is the concentration of ferrocyanide (5×10 − 6 mol cm − 3 ) and ν is the scan rate. The results indicate an increased active surface area with each modification step, with ss-DNA/MoS 2 /RGO/CPE having the highest surface area, facilitating more electrochemical reaction sites. The morphological changes on the electrode surface lead to an increase in the active surface area, favoring good electrocatalytic activity towards the redox behavior of CAP. 3.3. Electro-reduction of CAP at CPE modified electrodes The electrochemical behavior of CAP was investigated using CPE and modified electrodes through cyclic voltammetry. Figure 4 compares the electrodes (CPE, RGO/CPE, MoS 2 /RGO/CPE, and ss-DNA/MoS 2 /RGO/CPE) in the presence of 100 µM CAP in 0.1 M phosphate buffer solution at pH 5. The results indicate that the presence of RGO, MoS 2 , and DNA significantly improved the electrochemical responses for CAP, with ss-DNA/MoS 2 /RGO/CPE showing the highest cathodic current for CAP reduction. The increase in peak current at ss-DNA/MoS 2 /RGO/CPE indicates strong accumulation of CAP with increased electron transfer between CAP and the electrode surface. The electro-reduction mechanism of CAP on the modified electrode surface is presented in scheme 2 . 3.4. Electrochemical response of developed ss-DNA/MoS 2 /RGO/CPE sensor toward CAP sensing The electrochemical behavior of CAP at bare and modified electrodes was further investigated using differential pulse voltammetry (DPV) in 0.1 M phosphate buffer at pH 5 in the presence of 10 µM CAP. Figure 5 shows DPV voltammograms of CAP at bare and modified electrodes, indicating that the modified electrodes exhibit CAP reduction peaks at lower potentials compared to the unmodified electrode. The ss-DNA/MoS 2 /RGO/CPE demonstrated the highest cathodic current for CAP reduction, suggesting a catalytic effect due to the presence of RGO, MoS 2 , and DNA with a high surface area. 3.5. Investigation of the parameters affecting the sensor response 3.5.1. Influence of pH on electrochemical reduction of CAP The effect of solution pH on the peak current and peak potential in the presence of 10 µM CAP was studied using DPV in the pH range of 1–7. The peak current was observed to be highest at pH 5, indicating optimal conditions for CAP reduction (Fig. 6 ). The peak potential shifted towards lower potential with an increase in pH, suggesting a significant influence of the supporting electrolyte pH on electro-reduction of CAP at ss-DNA/MoS 2 /RGO/CPE. 3.5.2. Effect of scan rate on the electrochemical reduction of CAP The scan rate's influence on the reduction peak current of CAP was studied at ss-DNA/MoS 2 /RGO/CPE. Cyclic voltammograms at various scan rates (10 − 150 mV s − 1 ) revealed that the reduction peak current increased linearly with the scan rate (Fig. 7 ). Additionally, the anodic peak potential shifted towards a more positive potential with an increasing scan rate, indicating the irreversibility of CAP at ss-DNA/MoS 2 /RGO/CPE. 3.6. Analytical applications 3.6.1. Validation of the analytical procedure To assess the proposed method's feasibility for the trace determination of CAP, DPVs were recorded at least three times under optimized conditions at the ss-DNA/MoS 2 /RGO/CPE electrode surface. The reduction peak currents were found to be proportional to the concentrations of CAP in the range of 1×10 − 6 M to 60×10 − 6 M in 0.1 M phosphate buffer at pH 5 (Fig. 8 ). Two linear regression equations were obtained corresponding to different concentration ranges: I p (µA) = 1.3936 [CAP/(µM)] + 4.386 (R 2 = 0.9932) I p (µA) = 0.0296 [CAP/(µM)] + 17.653 (R 2 = 0.9989) The limit of detection (LOD) and the limit of quantification (LOQ) were determined as 0.0108 µM and 0.036 µM, respectively. The analytical parameters of the developed electrode were compared with previous works, indicating comparable sensitivity and applicability for CAP sensing (Table III). 3.6.2. Determination of CAP in real samples The designed sensor's sensitivity and applicability for the electrochemical determination of CAP were evaluated using ss-DNA/MoS 2 /RGO/CPE in diluted human serum samples. The recovery, the standard deviation and relative standard deviation (RSD) were calculated for different concentrations of CAP added to diluted serum samples. Human serum obtained from healthy volunteers was diluted 20-fold with Phosphate buffer and then different amounts of stock analyte solutions were added to 10 ml of diluted serum and DPVs were recorded. The amounts of CAP in serum samples were then evaluated from the calibration graph. Based on the calibration curve the results obtained are reported in Table IV. The low RSD values for three measurements (n = 3) confirmed the accuracy and precision of the proposed method for analyzing CAP in real samples. The sensor demonstrated potential for precise and sensitive analysis, making it suitable for diagnosis applications with acceptable reproducibility. 4. Conclusion This study introduced a rapid and cost-effective method for fabricating electrochemical sensors utilizing a carbon paste electrode (CPE) modified with RGO, MoS 2 , and ss-DNA. The optimization of electrode material compositions and experimental conditions, including pH and potential scan rate, was conducted to enhance sensitivity in detecting CAP. The electrochemical reduction of CAP was investigated using the optimized carbon paste electrode (ss-DNA/MoS 2 /RGO/CPE) in a phosphate buffer solution under optimal conditions of pH 5 and a scan rate of 100 mVs − 1 . Under these conditions, the ss-DNA/MoS 2 /RGO/CPE demonstrated a linear dynamic range from 0.01×10 − 6 M to 60×10 − 6 M, with a low detection limit of 15.0×10 − 8 M. The developed sensor displayed excellent reversibility and was successfully applied to determine CAP in spiked physiological samples, exhibiting robust recovery values ranging from 96.93–101.67%. Notably, the sensor exhibited minimal interference from coexisting substrates, underscoring its reliability for practical applications. Declarations Author Contribution 1) Masoumeh Mohammadi: Investigation, Methodology, Visualization, Writing-original draft, Data curation, Formal analysis, Software. 2) Amir Abbas Rafati: Project administration, Conceptualization, Supervision, Funding acquisition, Writing-review & editing, Resource, Validation. References Sung H, Ferlay J, Siegel RL, Laversanne M, Soerjomataram I, Jemal A, Bray F (2021) Global Cancer Statistics 2020: GLOBOCAN Estimates of Incidence and Mortality Worldwide for 36 Cancers in 185 Countries, CA-Cancer. J Clin 71:209–249. 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Tables Table I: Peak current response characteristics of the carbon paste electrodes with different Compositions I(µA) DNA(µl) Molybdenum disulfide ( MOS 2 ) % Reduced graphene oxide( RGO)% paraffin% Graphite powder% Electrode Sample No 32 0 0 0 25 75 CP E 1 40 0 0 10 25 65 CP+RGO(1) E 2 41 0 0 1 25 74 CP+RGO(2) E 3 39 0 0 0.1 25 74.9 CP+RGO(3) E 4 46 0 10 1 25 64 CP+RGO(4)+MoS 2 E 5 47 0 1 1 25 73 CP+RGO(4)+MoS 2 E 6 45 0 0.1 1 25 73.9 CP+RGO(4)+MoS 2 E 7 47 1µl 1 1 25 74 CP+RGO(4)+MoS 2 +DNA E 8 48 5µl 1 1 25 74 CP+RGO(4)+MoS 2 +DNA E 9 49 7µl 1 1 25 74 CP+RGO(4)+MoS 2 +DNA E 10 52 10µl 1 1 25 74 CP+RGO(4)+MoS 2 +DNA E 11 non 20µl 1 1 25 74 CP+RGO(4)+MoS 2 +DNA E 12 Table II: Calculated active surface area for each electrode using the Randles–Sevĉik equation . Active Surface Area (cm²) Modified Electrode 0.0076 CP 0.25 CP+RGO 0.33 CP+RGO+MoS 2 0.43 CP+RGO+MoS 2 +DNA Table III: A critical comparison of LOD and LDR values for CAP with other reported methods. Method Electrode LDR (µM) LOD(µM) Ref. SWV Fe3O4@GO@MIP/GCE 0.001–0.1 3.24×10 -4 [34] DPV AuNPs/SGNF/GCE 0.05-80.0 0.017 [35] DPV ZnO/MWCNT/CPE 0.1-100.0 0.030 [36] DPV MWCNT-PUFIX/HF-PGE 7.70–142.00 0.11 [37] DPV GCE 0.80-50 0.113 [38] DPV ss-DNA/MoS 2 /RGO/CPE 0.036-60 0.0108 This work Schemes Schemes are available in the Supplementary Files section. Additional Declarations No competing interests reported. Supplementary Files Scheme1.png Scheme 1: Chemical structure of capecitabine (CAP). Scheme2.png Scheme 2: Suggested electrochemical oxidation mechanism for CAP on the MoS 2 /RGO/CPE modified electrode. Cite Share Download PDF Status: Posted Version 1 posted 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. 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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-4006078","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":276222496,"identity":"b8fcdca2-eedc-47d6-935b-77c614f26a0b","order_by":0,"name":"Masoumeh Mohammadi","email":"","orcid":"","institution":"Bu-Ali Sina University","correspondingAuthor":false,"prefix":"","firstName":"Masoumeh","middleName":"","lastName":"Mohammadi","suffix":""},{"id":276222497,"identity":"2c59bef6-40b3-4ada-b9e7-40b9ad225243","order_by":1,"name":"Amirabbas Rafati","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA1klEQVRIiWNgGAWjYFACxgcMDAZAmr2BgZlILcwGDAdAWngOkKQFREskEKnFvP0w4+cPBQzy/DPfGH4uqLBh4G/vTsCrReZMMrME0GGGM27nGEvPOJPGIHHm7Aa8WiQY8g+AtDA23M4xkOZtO8xgIJFLQAv/Y+YfQC3282+eMf5NnBaJZDaQLYkbbvCYEWmLxGM2izMGDMkbz6SVWfOcSeMh7Bf+ZOYbFX8YbOcdP7z5Nk+FjRx/ey9+LVDwH4g5QBHKwEOMchhgf0CK6lEwCkbBKBhBAADl4kLiZK84HgAAAABJRU5ErkJggg==","orcid":"","institution":"Bu-Ali Sina University","correspondingAuthor":true,"prefix":"","firstName":"Amirabbas","middleName":"","lastName":"Rafati","suffix":""}],"badges":[],"createdAt":"2024-03-02 09:44:18","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-4006078/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-4006078/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":52099182,"identity":"f9c135bb-3041-4765-94df-caf923275d40","added_by":"auto","created_at":"2024-03-06 17:32:40","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":1841973,"visible":true,"origin":"","legend":"\u003cp\u003eSEM images of (a) RGO, (b) MoS\u003csub\u003e2\u003c/sub\u003e, (c) MoS\u003csub\u003e2\u003c/sub\u003e/RGO/CPE electrode.\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-4006078/v1/ea65654fb8617c0ccb3ae5e2.png"},{"id":52098914,"identity":"bf9d4d33-828e-4e80-ae24-d83f68f50992","added_by":"auto","created_at":"2024-03-06 17:24:40","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":744582,"visible":true,"origin":"","legend":"\u003cp\u003eEDX spectrum of MoS\u003csub\u003e2\u003c/sub\u003e/RGO/CPE.\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-4006078/v1/fa7981e28944235d5e03655d.png"},{"id":52098915,"identity":"fdb5dde8-f5aa-4f8f-be5d-17223541e869","added_by":"auto","created_at":"2024-03-06 17:24:40","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":190312,"visible":true,"origin":"","legend":"\u003cp\u003eCyclic voltammograms of K\u003csub\u003e3\u003c/sub\u003eFe(CN)\u003csub\u003e6\u003c/sub\u003e (5.0×10\u003csup\u003e-3\u003c/sup\u003e M)/KCl (0.1 M) in PBS 0.1 M\u003cbr\u003e\n\u0026nbsp;(pH 5.0) at (a) bare CPE, (b) RGO/CPE, and (c) MoS\u003csub\u003e2\u003c/sub\u003e/RGO/CPE and (d) ss-DNA/MoS\u003csub\u003e2\u003c/sub\u003e/RGO/CPE.\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-4006078/v1/93bebac18485e568edd6ce66.png"},{"id":52098917,"identity":"f5da30fe-997e-476e-8768-04281b3df7be","added_by":"auto","created_at":"2024-03-06 17:24:40","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":223707,"visible":true,"origin":"","legend":"\u003cp\u003eCyclic voltammograms of CAP (100 µM) in PBS 0.1 M (pH 5) at a scan rate of 100 mV s\u003csup\u003e−1\u003c/sup\u003e recorded at the surface of (a) bare CPE, (b) RGO/CPE, (c) MoS\u003csub\u003e2\u003c/sub\u003e/RGO/CPE, and (d) ss-DNA/MoS\u003csub\u003e2\u003c/sub\u003e/RGO/CPE.\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-4006078/v1/4e144217b8b7f54ab65c7356.png"},{"id":52098913,"identity":"62de9768-3c2e-4f11-b460-7b2d7f23e000","added_by":"auto","created_at":"2024-03-06 17:24:40","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":172513,"visible":true,"origin":"","legend":"\u003cp\u003eDPV voltammograms of 10 µM CAP recorded at (a) bare CPE, (b) RGO/CPE, (c) MoS\u003csub\u003e2\u003c/sub\u003e/RGO/CPE, and (d) ss-DNA/MoS\u003csub\u003e2\u003c/sub\u003e/RGO/CPE electrodes in phosphate buffer pH 5.\u003c/p\u003e","description":"","filename":"5.png","url":"https://assets-eu.researchsquare.com/files/rs-4006078/v1/6446f82f23cf4a8a495e27df.png"},{"id":52099183,"identity":"8c9a2505-ce62-40be-9163-7ce90a26b60b","added_by":"auto","created_at":"2024-03-06 17:32:40","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":339157,"visible":true,"origin":"","legend":"\u003cp\u003e(a) DPVs obtained for 5.0 µM CAP in phosphate buffer solution at different pH values; (b) Influence of pH on the peak current (\u003cem\u003eI\u003c/em\u003ep); and (c) Influence of pH on the peak potential (\u003cem\u003eE\u003c/em\u003ep).\u003c/p\u003e","description":"","filename":"6.png","url":"https://assets-eu.researchsquare.com/files/rs-4006078/v1/65567f2965a4ef91ca06e9d2.png"},{"id":52099184,"identity":"1ed3d180-8c97-461e-992b-3b768879d7af","added_by":"auto","created_at":"2024-03-06 17:32:40","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":98750,"visible":true,"origin":"","legend":"\u003cp\u003e(a) CVs of 100 μM CAP in 0.1 M phosphate buffer solution (pH=5) at different scan rates of 10-150 mV/s; (b) The variation of the peak current with (b) the scan rate, (c) the square root of the scan rate, and (d) variation of log(\u003cem\u003eI\u003c/em\u003e) with log(n).\u003c/p\u003e","description":"","filename":"7.png","url":"https://assets-eu.researchsquare.com/files/rs-4006078/v1/7eacc814d559d93fb1e41acb.png"},{"id":52098916,"identity":"a6a0e2a3-6c52-46dc-8fe3-feeeaa5d57da","added_by":"auto","created_at":"2024-03-06 17:24:40","extension":"png","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":76873,"visible":true,"origin":"","legend":"\u003cp\u003eThe plot of peak current against the CAP concentration as calibration curve.\u003c/p\u003e","description":"","filename":"8.png","url":"https://assets-eu.researchsquare.com/files/rs-4006078/v1/5882c237d133607dedbeb858.png"},{"id":53769963,"identity":"d2b06d92-0cc5-4016-9df8-a5d148a49177","added_by":"auto","created_at":"2024-03-30 04:37:42","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1902577,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-4006078/v1/fc530734-66a8-4eef-b16d-0e9342076079.pdf"},{"id":52098910,"identity":"5982e58b-efab-4862-ae42-dd9d3d6bdb82","added_by":"auto","created_at":"2024-03-06 17:24:39","extension":"png","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":99639,"visible":true,"origin":"","legend":"\u003cp\u003eScheme 1: Chemical structure of capecitabine\u003cstrong\u003e \u003c/strong\u003e(CAP).\u003c/p\u003e","description":"","filename":"Scheme1.png","url":"https://assets-eu.researchsquare.com/files/rs-4006078/v1/bb6948030f05998c386f1e76.png"},{"id":52098911,"identity":"77c5b6e2-10ae-4d64-b405-c82c0ef5e988","added_by":"auto","created_at":"2024-03-06 17:24:40","extension":"png","order_by":2,"title":"","display":"","copyAsset":false,"role":"supplement","size":121612,"visible":true,"origin":"","legend":"\u003cp\u003eScheme 2: Suggested electrochemical oxidation mechanism for CAP on the MoS\u003csub\u003e2\u003c/sub\u003e/RGO/CPE modified electrode.\u003c/p\u003e","description":"","filename":"Scheme2.png","url":"https://assets-eu.researchsquare.com/files/rs-4006078/v1/382371d9cb90cacb5082693c.png"}],"financialInterests":"No competing interests reported.","formattedTitle":"A sensitive electrochemical DNA biosensor for determination of Capecitabine anticancer drug based on ss-DNA/RGO/MoS2/CPE electrode","fulltext":[{"header":"1. Introduction","content":"\u003cp\u003eCancer remains one of the most formidable challenges to global public health, necessitating continuous advancements in diagnostic and therapeutic strategies [\u003cspan additionalcitationids=\"CR2 CR3 CR4\" citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. CAP (scheme \u003cspan refid=\"Sch1\" class=\"InternalRef\"\u003e1\u003c/span\u003e), a prodrug used in the treatment of various cancers, exemplifies the importance of precise monitoring to ensure optimal therapeutic outcomes while minimizing potential side effects [\u003cspan additionalcitationids=\"CR7\" citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eElectrochemical methods offer distinct advantages over other techniques for the determination of drug compounds, showcasing their applicability and efficiency in pharmaceutical analysis. One primary advantage lies in their high sensitivity, allowing for the detection of low concentrations of drugs, even in complex matrices. Additionally, electrochemical methods often exhibit excellent selectivity, minimizing interference from coexisting substances and enhancing the accuracy of drug quantification. The real-time monitoring capabilities of electrochemical techniques enable dynamic studies of drug behavior and kinetics, providing valuable insights into their electroactive properties. Moreover, these methods are inherently cost-effective, as they generally require simpler instrumentation and offer a rapid analysis turnaround. Overall, the versatility, sensitivity, selectivity, and cost-effectiveness of electrochemical methods position them as powerful tools for drug determination, contributing significantly to advancements in pharmaceutical research and development [\u003cspan additionalcitationids=\"CR10 CR11 CR12\" citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eAmong the electrochemical methods, electrochemical sensor and biosensors possess several advantages including high sensitivity and selectivity, rapid response time, miniaturization and portability, low cost and simple instrumentation, operational versatility, real-time monitoring and continuous measurement, wide range of applicability, ease of functionalization [\u003cspan additionalcitationids=\"CR15 CR16 CR17 CR18 CR19 CR20 CR21 CR22\" citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e]. These advantages collectively make electrochemical sensors powerful tools for monitoring and quantifying various analytes in a wide range of fields, contributing to their widespread use and ongoing research and development In recent years, electrochemical DNA biosensors have gained prominence in recent years due to their high sensitivity, rapid response, and specificity in detecting target molecules [\u003cspan additionalcitationids=\"CR25 CR26 CR27\" citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e]. The integration of advanced nanomaterials further enhances the performance of these biosensors, offering improved electrocatalytic properties and a larger surface area for enhanced biomolecular interactions [\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eIn this context, the development of sensitive and reliable biosensors for the detection of anticancer drugs has emerged as a crucial area of research. It is based on a novel electrochemical DNA biosensor designed for the specific determination of CAP, a widely utilized chemotherapeutic agent. The biosensor is constructed using a hybrid nanomaterial platform comprising reduced graphene oxide (RGO), molybdenum disulfide (MoS\u003csub\u003e2\u003c/sub\u003e), and a carbon paste electrode [\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e]. The synergistic effects of these materials contribute to the enhanced electrochemical performance of the biosensor, facilitating the sensitive and selective detection of CAP in complex biological matrices. The rational design and fabrication of the RGO/MoS\u003csub\u003e2\u003c/sub\u003e/carbon paste electrode aim to overcome challenges associated with the detection of CAP, such as low concentrations and potential interference from other biomolecules [\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e]. The utilization of DNA as a recognition element adds an additional layer of specificity, enabling the biosensor to discriminate CAP from structurally similar compounds [\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e].\u003c/p\u003e"},{"header":"2. Experimental","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003e2.1 Reagents and Apparatus\u003c/h2\u003e \u003cp\u003eCAP drug was acquired from Sobhan Oncology Company (Iran). Ascorbic acid (AA), uric acid (UA), folic acid (AF), and highly pure paraffin were procured from Sigma-Aldrich Chemical Co. Graphite powder was obtained from Sinchem, Korea.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003e2.2. Synthesis of Graphene Oxide\u003c/h2\u003e \u003cp\u003eGraphene oxide was prepared from natural graphite using the well-known Hummers method [\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e]. In a typical synthesis process, 2 g of graphite powder was added to 46 ml concentrated H\u003csub\u003e2\u003c/sub\u003eSO\u003csub\u003e4\u003c/sub\u003e at 0\u0026deg;C, followed by the gradual addition of 6 g KMnO\u003csub\u003e4\u003c/sub\u003e under magnetic stirring at 15\u0026deg;C. The mixture was stirred at 35\u0026deg;C for 40 min, with the temperature slowly increasing to 40\u0026deg;C. Simultaneously, 100 ml of distilled water was added slowly, maintaining the temperature for 30 min under reflux conditions. After the reaction, 300 ml of distilled water followed by 20 ml of 30% H\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e2\u003c/sub\u003e solution was added, resulting in a golden solution. The solid product was separated by centrifugation, washed with 10% HCl solution, and water. The final product was dried in a vacuum oven at 60\u0026deg;C overnight, yielding lamellar solids for subsequent experiments.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003e2.3. Preparation of Reduced Graphene Oxide (RGO) by Hydrothermal Method\u003c/h2\u003e \u003cp\u003eInitially, 1 g of as-synthesized graphene oxide (GO) was suspended in 100 ml ethanol through 100 minutes of sonication, yielding a brown colloidal solution. Subsequently, the solution was sealed in a 50 mL Teflon-lined autoclave and maintained at a temperature of 200\u0026deg;C for 20 hours. The solids were filtered, washed with acetone and distilled water, and then dried in a vacuum oven at 70\u0026deg;C overnight. The obtained solid was dissolved in 100 ml of chloroform for 30 minutes under ultrasonication, followed by centrifugation. The resulting solid was dried and analyzed. All other chemical reagents were of analytical grade and used without further purification. All aqueous solutions were prepared with deionized water.\u003c/p\u003e \u003cp\u003eHuman blood serum samples devoid of CAP were obtained from the Central Hamedan Clinical and Pathological Laboratory (Hamedan, Iran) and stored in a refrigerator immediately after collection before use.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec6\" class=\"Section2\"\u003e \u003ch2\u003e2.4. Synthesis of MoS\u003csub\u003e2\u003c/sub\u003e by Hydrothermal Method\u003c/h2\u003e \u003cp\u003eMoS\u003csub\u003e2\u003c/sub\u003e materials with different morphologies were synthesized via a simple hydrothermal method under acidic conditions using Sodium molybdate (Na\u003csub\u003e2\u003c/sub\u003eMoO\u003csub\u003e4\u003c/sub\u003e\u0026middot;2H\u003csub\u003e2\u003c/sub\u003eO), Thiourea (CH\u003csub\u003e4\u003c/sub\u003eN\u003csub\u003e2\u003c/sub\u003eS), and Polyethylene glycol (PEG) as starting materials. In a typical preparation process, 1.21 g Na\u003csub\u003e2\u003c/sub\u003eMoO\u003csub\u003e4\u003c/sub\u003e\u0026middot;2H\u003csub\u003e2\u003c/sub\u003eO (0.005 mol), 1.56 g CH\u003csub\u003e4\u003c/sub\u003eN\u003csub\u003e2\u003c/sub\u003eS (0.02 mol), and 0.14 g PEG were dissolved in 30 mL of deionized water and sonicated for 30 minutes. The mixed solution was transferred into a 50 mL Teflon-lined stainless-steel autoclave for hydrothermal treatment at 200\u0026deg;C for 48 hours and cooled to room temperature naturally. MoS\u003csub\u003e2\u003c/sub\u003e in the form of black powder was obtained by centrifugation at 4000 rpm for 10 minutes, washed with deionized water and ethanol, and dried in the vacuum oven at 60\u0026deg;C for 12 hours. The obtained MoS\u003csub\u003e2\u003c/sub\u003e product was analyzed.\u003c/p\u003e \u003cp\u003ePhosphoric acid (1.67 g/L) (Merck, Germany) and sodium hydroxide (Merck, Germany) solutions were used to prepare buffer solutions. The pH values of the buffer solutions were measured with a pH meter (Metrohm 744) with an accuracy of \u0026plusmn;\u0026thinsp;0.01 units.\u003c/p\u003e \u003cp\u003eThe stock solution (0.3 ppm ss-DNA) was prepared using Phosphate buffer solution and preserved in the freezer. Diluted solutions of DNA were prepared using Phosphate buffer solution.\u003c/p\u003e \u003cp\u003eAll voltammetric measurements were carried out using a \u0026micro;-autolab modular electrochemical system (PGSTAT101, Metrohm, Netherlands), and NOVA 1.7 software was applied for data recording. All electrochemical experiments were conducted at room temperature using a conventional 25 mL three-electrode glass cell containing an Ag/AgCl reference electrode, a platinum plate counter electrode, and a modified carbon paste electrode (CPE) as the working electrode.\u003c/p\u003e \u003cp\u003eScanning electron microscopy (SEM) (Model Quanta 250 Field Emission Gun) coupled with energy dispersive analysis of X-ray (EDX) Unit (FEI Company, USA) were used for the analysis of the electrode surface morphology and compositions.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec7\" class=\"Section2\"\u003e \u003ch2\u003e2.5. Preparation of ss-DNA/ MoS\u003csub\u003e2\u003c/sub\u003e/RGO/CPE Electrode\u003c/h2\u003e \u003cp\u003eThe modified CPEs were prepared by hand mixing a mixture of graphite powder, RGO, MoS\u003csub\u003e2\u003c/sub\u003e, ss-DNA and paraffin oil with various ratios (w/w) presented in Table I in a mortar for at least 40 minutes.\u003c/p\u003e \u003cp\u003eThe modified carbon paste was packed into the tip of a 1 mL insulin plastic syringe, and a copper wire was inserted to obtain external electric contact. The electrode surface was polished with a piece of soft paper to prepare the electrode. A new surface was obtained by cutting the end of the tube and rinsed carefully with deionized water before each measurement. Electrochemical parameters of CPEs were obtained with voltammetric measurement analysis in a 5.0 mM K\u003csub\u003e3\u003c/sub\u003e[Fe(CN)\u003csub\u003e6\u003c/sub\u003e] solution. The prepared MoS\u003csub\u003e2\u003c/sub\u003e/RGO/CPE was thoroughly washed with deionized water and dried before use. Then, a droplet of 10 \u0026micro;L of 0.3 g/mL ss-DNA solution in phosphate buffer was dropped onto the surface of the MoS\u003csub\u003e2\u003c/sub\u003e/RGO/CPE and incubated for 24 hours at 4\u0026deg;C before use.\u003c/p\u003e \u003c/div\u003e"},{"header":"3. Results and Discussion","content":"\u003cdiv id=\"Sec9\" class=\"Section2\"\u003e \u003ch2\u003e3.1. Surface Characterization of Modified Electrode\u003c/h2\u003e \u003cp\u003eTo investigate the surface morphology and the modifying effect of RGO and MoS\u003csub\u003e2\u003c/sub\u003e on the CPE, SEM images were captured before and after electrode modification. Figures\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e1\u003c/span\u003ea, \u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e1\u003c/span\u003eb, and \u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e1\u003c/span\u003ec present SEM images of the composite RGO/MoS\u003csub\u003e2\u003c/sub\u003e/CPE, revealing MoS\u003csub\u003e2\u003c/sub\u003e dispersed on the surface of RGO and the graphite matrix.\u003c/p\u003e \u003cp\u003eThe presence of RGO and MoS\u003csub\u003e2\u003c/sub\u003e significantly increased the surface area and porosity of the electrode, enhancing the efficiency of the modified electrode. The EDX spectrum in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e2\u003c/span\u003e confirms that the carbon paste electrode modified with RGO and MoS\u003csub\u003e2\u003c/sub\u003e is suitable for electrocatalysis.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec10\" class=\"Section2\"\u003e \u003ch2\u003e3.2. Electrochemical Characterization of Modified Electrodes\u003c/h2\u003e \u003cp\u003eCyclic voltammetry (CV) was employed to characterize both modified and bare electrodes using a 5.0 mM K\u003csub\u003e3\u003c/sub\u003eFe(CN)\u003csub\u003e6\u003c/sub\u003e probe. Figure\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e3\u003c/span\u003e illustrates the cyclic voltammograms of CPE, RGO/CPE, MoS\u003csub\u003e2\u003c/sub\u003e/RGO/CPE, and\u003c/p\u003e \u003cp\u003ess-DNA/MoS\u003csub\u003e2\u003c/sub\u003e/RGO/CPE in the potential range of -0.2 V to +\u0026thinsp;1.0 V. The electrode response improved upon adding RGO and MoS\u003csub\u003e2\u003c/sub\u003e to the carbon paste electrode materials. The increased current peaks for modified electrodes can be attributed to the enhanced electron transfer rate and increased active surface sites due to the modification.\u003c/p\u003e \u003cp\u003eAdditionally, the active surface area of the electrodes was determined using the [Fe(CN)\u003csub\u003e6\u003c/sub\u003e]\u003csup\u003e3\u0026minus;/4\u0026minus;\u003c/sup\u003e redox system at different potential scan rates. The Randles\u0026ndash;Sevĉik equation (Eq.\u0026nbsp;1) for a reversible process was applied, and the calculated active surface areas for each electrode are tabulated in Table II.\u003cdiv class=\"BlockQuote\"\u003e\u003cp\u003e \u003cem\u003eI\u003c/em\u003e \u003csub\u003e\u003cem\u003epa\u003c/em\u003e\u003c/sub\u003e = 2.69 \u0026times; 10\u003csup\u003e5\u003c/sup\u003e \u003cem\u003en\u003c/em\u003e\u003csup\u003e3\u003c/sup\u003e\u003cem\u003eA\u003c/em\u003e\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\({ D}_{R}^{1/2}{\\nu }^{1/2}{\\text{C}}_{0}\\)\u003c/span\u003e\u003c/span\u003e (1)\u003c/p\u003e\u003c/div\u003e\u003c/p\u003e \u003cp\u003ewhere \u003cem\u003en\u003c/em\u003e is the number of transferred electrons in the oxidation and reduction process of ferrocyanide, \u003cem\u003eC\u003c/em\u003e\u003csub\u003e0\u003c/sub\u003e is the concentration of ferrocyanide (5\u0026times;10\u003csup\u003e\u0026minus;\u0026thinsp;6\u003c/sup\u003e mol cm\u003csup\u003e\u0026minus;\u0026thinsp;3\u003c/sup\u003e) and \u003cem\u003eν\u003c/em\u003e is the scan rate.\u003c/p\u003e \u003cp\u003eThe results indicate an increased active surface area with each modification step, with ss-DNA/MoS\u003csub\u003e2\u003c/sub\u003e/RGO/CPE having the highest surface area, facilitating more electrochemical reaction sites. The morphological changes on the electrode surface lead to an increase in the active surface area, favoring good electrocatalytic activity towards the redox behavior of CAP.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec11\" class=\"Section2\"\u003e \u003ch2\u003e3.3. Electro-reduction of CAP at CPE modified electrodes\u003c/h2\u003e \u003cp\u003eThe electrochemical behavior of CAP was investigated using CPE and modified electrodes through cyclic voltammetry. Figure\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e4\u003c/span\u003e compares the electrodes (CPE, RGO/CPE, MoS\u003csub\u003e2\u003c/sub\u003e/RGO/CPE, and ss-DNA/MoS\u003csub\u003e2\u003c/sub\u003e/RGO/CPE) in the presence of 100 \u0026micro;M CAP in 0.1 M phosphate buffer solution at pH 5. The results indicate that the presence of RGO, MoS\u003csub\u003e2\u003c/sub\u003e, and DNA significantly improved the electrochemical responses for CAP, with ss-DNA/MoS\u003csub\u003e2\u003c/sub\u003e/RGO/CPE showing the highest cathodic current for CAP reduction.\u003c/p\u003e \u003cp\u003eThe increase in peak current at ss-DNA/MoS\u003csub\u003e2\u003c/sub\u003e/RGO/CPE indicates strong accumulation of CAP with increased electron transfer between CAP and the electrode surface. The electro-reduction mechanism of CAP on the modified electrode surface is presented in scheme \u003cspan refid=\"Sch2\" class=\"InternalRef\"\u003e2\u003c/span\u003e.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec12\" class=\"Section2\"\u003e \u003ch2\u003e3.4. Electrochemical response of developed ss-DNA/MoS\u003csub\u003e2\u003c/sub\u003e/RGO/CPE sensor toward CAP sensing\u003c/h2\u003e \u003cp\u003eThe electrochemical behavior of CAP at bare and modified electrodes was further investigated using differential pulse voltammetry (DPV) in 0.1 M phosphate buffer at pH 5 in the presence of 10 \u0026micro;M CAP. Figure\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e5\u003c/span\u003e shows DPV voltammograms of CAP at bare and modified electrodes, indicating that the modified electrodes exhibit CAP reduction peaks at lower potentials compared to the unmodified electrode. The ss-DNA/MoS\u003csub\u003e2\u003c/sub\u003e/RGO/CPE demonstrated the highest cathodic current for CAP reduction, suggesting a catalytic effect due to the presence of RGO, MoS\u003csub\u003e2\u003c/sub\u003e, and DNA with a high surface area.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec13\" class=\"Section2\"\u003e \u003ch2\u003e3.5. Investigation of the parameters affecting the sensor response\u003c/h2\u003e \u003cdiv id=\"Sec14\" class=\"Section3\"\u003e \u003ch2\u003e3.5.1. Influence of pH on electrochemical reduction of CAP\u003c/h2\u003e \u003cp\u003eThe effect of solution pH on the peak current and peak potential in the presence of 10 \u0026micro;M CAP was studied using DPV in the pH range of 1\u0026ndash;7. The peak current was observed to be highest at pH 5, indicating optimal conditions for CAP reduction (Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e6\u003c/span\u003e). The peak potential shifted towards lower potential with an increase in pH, suggesting a significant influence of the supporting electrolyte pH on electro-reduction of CAP at ss-DNA/MoS\u003csub\u003e2\u003c/sub\u003e/RGO/CPE.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec15\" class=\"Section3\"\u003e \u003ch2\u003e3.5.2. Effect of scan rate on the electrochemical reduction of CAP\u003c/h2\u003e \u003cp\u003eThe scan rate's influence on the reduction peak current of CAP was studied at ss-DNA/MoS\u003csub\u003e2\u003c/sub\u003e/RGO/CPE. Cyclic voltammograms at various scan rates (10\u0026thinsp;\u0026minus;\u0026thinsp;150 mV s\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e) revealed that the reduction peak current increased linearly with the scan rate (Fig.\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e7\u003c/span\u003e). Additionally, the anodic peak potential shifted towards a more positive potential with an increasing scan rate, indicating the irreversibility of CAP at ss-DNA/MoS\u003csub\u003e2\u003c/sub\u003e/RGO/CPE.\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv id=\"Sec16\" class=\"Section2\"\u003e \u003ch2\u003e3.6. Analytical applications\u003c/h2\u003e \u003cdiv id=\"Sec17\" class=\"Section3\"\u003e \u003ch2\u003e3.6.1. Validation of the analytical procedure\u003c/h2\u003e \u003cp\u003eTo assess the proposed method's feasibility for the trace determination of CAP, DPVs were recorded at least three times under optimized conditions at the ss-DNA/MoS\u003csub\u003e2\u003c/sub\u003e/RGO/CPE electrode surface. The reduction peak currents were found to be proportional to the concentrations of CAP in the range of 1\u0026times;10\u003csup\u003e\u0026minus;\u0026thinsp;6\u003c/sup\u003e M to 60\u0026times;10\u003csup\u003e\u0026minus;\u0026thinsp;6\u003c/sup\u003e M in 0.1 M phosphate buffer at pH 5 (Fig.\u0026nbsp;\u003cspan refid=\"Fig9\" class=\"InternalRef\"\u003e8\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eTwo linear regression equations were obtained corresponding to different concentration ranges:\u003cdiv class=\"BlockQuote\"\u003e\u003cp\u003e \u003cem\u003eI\u003c/em\u003e \u003csub\u003ep\u003c/sub\u003e(\u0026micro;A)\u0026thinsp;=\u0026thinsp;1.3936 [CAP/(\u0026micro;M)]\u0026thinsp;+\u0026thinsp;4.386 (R\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;0.9932)\u003c/p\u003e\u003cp\u003e \u003cem\u003eI\u003c/em\u003e \u003csub\u003ep\u003c/sub\u003e(\u0026micro;A)\u0026thinsp;=\u0026thinsp;0.0296 [CAP/(\u0026micro;M)]\u0026thinsp;+\u0026thinsp;17.653 (R\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;0.9989)\u003c/p\u003e\u003c/div\u003e\u003c/p\u003e \u003cp\u003eThe limit of detection (LOD) and the limit of quantification (LOQ) were determined as 0.0108 \u0026micro;M and 0.036 \u0026micro;M, respectively. The analytical parameters of the developed electrode were compared with previous works, indicating comparable sensitivity and applicability for CAP sensing (Table III).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec18\" class=\"Section3\"\u003e \u003ch2\u003e3.6.2. Determination of CAP in real samples\u003c/h2\u003e \u003cp\u003eThe designed sensor's sensitivity and applicability for the electrochemical determination of CAP were evaluated using ss-DNA/MoS\u003csub\u003e2\u003c/sub\u003e/RGO/CPE in diluted human serum samples. The recovery, the standard deviation and relative standard deviation (RSD) were calculated for different concentrations of CAP added to diluted serum samples. Human serum obtained from healthy volunteers was diluted 20-fold with Phosphate buffer and then different amounts of stock analyte solutions were added to 10 ml of diluted serum and DPVs were recorded. The amounts of CAP in serum samples were then evaluated from the calibration graph. Based on the calibration curve the results obtained are reported in Table IV.\u003c/p\u003e \u003cp\u003eThe low RSD values for three measurements (n\u0026thinsp;=\u0026thinsp;3) confirmed the accuracy and precision of the proposed method for analyzing CAP in real samples. The sensor demonstrated potential for precise and sensitive analysis, making it suitable for diagnosis applications with acceptable reproducibility.\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e"},{"header":"4. Conclusion","content":"\u003cp\u003eThis study introduced a rapid and cost-effective method for fabricating electrochemical sensors utilizing a carbon paste electrode (CPE) modified with RGO, MoS\u003csub\u003e2\u003c/sub\u003e, and ss-DNA. The optimization of electrode material compositions and experimental conditions, including pH and potential scan rate, was conducted to enhance sensitivity in detecting CAP.\u003c/p\u003e \u003cp\u003eThe electrochemical reduction of CAP was investigated using the optimized carbon paste electrode (ss-DNA/MoS\u003csub\u003e2\u003c/sub\u003e/RGO/CPE) in a phosphate buffer solution under optimal conditions of pH 5 and a scan rate of 100 mVs\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e. Under these conditions, the ss-DNA/MoS\u003csub\u003e2\u003c/sub\u003e/RGO/CPE demonstrated a linear dynamic range from 0.01\u0026times;10\u003csup\u003e\u0026minus;\u0026thinsp;6\u003c/sup\u003e M to 60\u0026times;10\u003csup\u003e\u0026minus;\u0026thinsp;6\u003c/sup\u003e M, with a low detection limit of 15.0\u0026times;10\u003csup\u003e\u0026minus;\u0026thinsp;8\u003c/sup\u003e M.\u003c/p\u003e \u003cp\u003eThe developed sensor displayed excellent reversibility and was successfully applied to determine CAP in spiked physiological samples, exhibiting robust recovery values ranging from 96.93\u0026ndash;101.67%. Notably, the sensor exhibited minimal interference from coexisting substrates, underscoring its reliability for practical applications.\u003c/p\u003e"},{"header":"Declarations","content":"\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003e1) Masoumeh Mohammadi: Investigation, Methodology, Visualization, Writing-original draft, Data curation, Formal analysis, Software. 2) Amir Abbas Rafati: Project administration, Conceptualization, Supervision, Funding acquisition, Writing-review \u0026amp; editing, Resource, Validation.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eSung H, Ferlay J, Siegel RL, Laversanne M, Soerjomataram I, Jemal A, Bray F (2021) Global Cancer Statistics 2020: GLOBOCAN Estimates of Incidence and Mortality Worldwide for 36 Cancers in 185 Countries, CA-Cancer. 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J Mater Chem 22:13707-13713. \u003c/li\u003e\n\u003cli\u003eAfzali M, Mostafavi A, Shamspur T (2020) A novel electrochemical sensor based on magnetic core@shell molecularly imprinted nanocomposite (Fe\u003csub\u003e3\u003c/sub\u003eO\u003csub\u003e4\u003c/sub\u003e@graphene oxide@MIP) for sensitive and selective determination of anticancer drug capecitabine. Arab J Chem 13:6626-6638. \u003c/li\u003e\n\u003cli\u003eZhang Q, Shan X, Fu Y, Liu P, Li X, Liu B, Zhang L, Li D (2017) Electrochemical Determination of the Anticancer Drug Capecitabine Based on a Graphene-Gold Nanocomposite-Modified Glassy Carbon Electrode. Int J Electrochem Sci 12:10773\u0026ndash;10782. \u003c/li\u003e\n\u003cli\u003eMadrakian T, Ghasemi H, Haghshenas E, Afkhami A (2016) Preparation of a ZnO nanoparticles/multiwalled carbon nanotubes/carbon paste electrode as a sensitive tool for capecitabine determination in real samples. RSC Advances 6:33851-33856\u003cspan dir=\"RTL\"\u003e.\u003c/span\u003e \u003c/li\u003e\n\u003cli\u003eEs\u0026apos;haghi Z, Moeinpour F (2019) Carbon nanotube/polyurethane modified hollow fiber-pencil graphite electrode for in situ concentration and electrochemical quantification of anticancer drugs Capecitabine and Erlotinib. Eng Life Sci 19:302\u0026ndash;314. \u003c/li\u003e\n\u003cli\u003eKalanur SS, Seetharamappa J, Mamatha GP, Hadagali MD, Kandagal PB (2008) Electrochemical Behavior of an Anti-Cancer Drug at Glassy Carbon Electrode and its Determination in Pharmaceutical Formulations. Int J Electrochem Sci 3:756\u0026ndash;767. \u003c/li\u003e\n\u003c/ol\u003e"},{"header":"Tables","content":"\u003cp\u003eTable I:\u0026nbsp;Peak current response characteristics of the carbon paste electrodes with different Compositions\u003c/p\u003e\n\u003cdiv\u003e\n \u003ctable dir=\"rtl\" border=\"1\" cellspacing=\"0\" cellpadding=\"0\" align=\"right\" width=\"854\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd width=\"5.971896955503513%\" style=\"width: 5.7989%;\"\u003e\n \u003cp dir=\"LTR\"\u003e\u003cstrong\u003eI(\u0026micro;A)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"8.430913348946136%\" style=\"width: 8.3764%;\"\u003e\n \u003cp dir=\"LTR\"\u003e\u003cstrong\u003eDNA(\u0026micro;l)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.519906323185012%\"\u003e\n \u003cp dir=\"LTR\"\u003e\u003cstrong\u003eMolybdenum disulfide ( MOS\u003csub\u003e2\u003c/sub\u003e) %\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"13.348946135831381%\"\u003e\n \u003cp dir=\"LTR\"\u003e\u003cstrong\u003eReduced graphene oxide( RGO)%\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"6.791569086651054%\"\u003e\n \u003cp dir=\"LTR\"\u003e\u003cstrong\u003eparaffin%\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"8.899297423887587%\"\u003e\n \u003cp dir=\"LTR\"\u003e\u003cstrong\u003eGraphite powder%\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"25.40983606557377%\"\u003e\n \u003cp dir=\"LTR\"\u003e\u003cstrong\u003eElectrode\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.627634660421545%\"\u003e\n \u003cp dir=\"LTR\"\u003e\u003cstrong\u003eSample No\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"5.971896955503513%\" style=\"width: 5.7989%;\"\u003e\n \u003cp dir=\"LTR\"\u003e32\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"8.430913348946136%\" style=\"width: 8.3764%;\"\u003e\n \u003cp dir=\"LTR\"\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.519906323185012%\"\u003e\n \u003cp dir=\"LTR\"\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"13.348946135831381%\"\u003e\n \u003cp dir=\"LTR\"\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"6.791569086651054%\"\u003e\n \u003cp dir=\"LTR\"\u003e25\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"8.899297423887587%\"\u003e\n \u003cp dir=\"LTR\"\u003e75\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"25.40983606557377%\"\u003e\n \u003cp dir=\"LTR\"\u003eCP\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.627634660421545%\"\u003e\n \u003cp dir=\"LTR\"\u003e\u003cstrong\u003eE\u003csub\u003e1\u003c/sub\u003e\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"5.971896955503513%\" style=\"width: 5.7989%;\"\u003e\n \u003cp dir=\"LTR\"\u003e40\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"8.430913348946136%\" style=\"width: 8.3764%;\"\u003e\n \u003cp dir=\"LTR\"\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.519906323185012%\"\u003e\n \u003cp dir=\"LTR\"\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"13.348946135831381%\"\u003e\n \u003cp dir=\"LTR\"\u003e10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"6.791569086651054%\"\u003e\n \u003cp dir=\"LTR\"\u003e25\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"8.899297423887587%\"\u003e\n \u003cp dir=\"LTR\"\u003e65\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"25.40983606557377%\"\u003e\n \u003cp dir=\"LTR\"\u003eCP+RGO(1)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.627634660421545%\"\u003e\n \u003cp dir=\"LTR\"\u003e\u003cstrong\u003eE\u003csub\u003e2\u003c/sub\u003e\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"5.971896955503513%\" style=\"width: 5.7989%;\"\u003e\n \u003cp dir=\"LTR\"\u003e41\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"8.430913348946136%\" style=\"width: 8.3764%;\"\u003e\n \u003cp dir=\"LTR\"\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.519906323185012%\"\u003e\n \u003cp dir=\"LTR\"\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"13.348946135831381%\"\u003e\n \u003cp dir=\"LTR\"\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"6.791569086651054%\"\u003e\n \u003cp dir=\"LTR\"\u003e25\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"8.899297423887587%\"\u003e\n \u003cp dir=\"LTR\"\u003e74\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"25.40983606557377%\"\u003e\n \u003cp dir=\"LTR\"\u003eCP+RGO(2)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.627634660421545%\"\u003e\n \u003cp dir=\"LTR\"\u003e\u003cstrong\u003eE\u003csub\u003e3\u003c/sub\u003e\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"5.971896955503513%\" style=\"width: 5.7989%;\"\u003e\n \u003cp dir=\"LTR\"\u003e39\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"8.430913348946136%\" style=\"width: 8.3764%;\"\u003e\n \u003cp dir=\"LTR\"\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.519906323185012%\"\u003e\n \u003cp dir=\"LTR\"\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"13.348946135831381%\"\u003e\n \u003cp dir=\"LTR\"\u003e0.1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"6.791569086651054%\"\u003e\n \u003cp dir=\"LTR\"\u003e25\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"8.899297423887587%\"\u003e\n \u003cp dir=\"LTR\"\u003e74.9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"25.40983606557377%\"\u003e\n \u003cp dir=\"LTR\"\u003eCP+RGO(3)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.627634660421545%\"\u003e\n \u003cp dir=\"LTR\"\u003e\u003cstrong\u003eE\u003csub\u003e4\u003c/sub\u003e\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"5.971896955503513%\" style=\"width: 5.7989%;\"\u003e\n \u003cp dir=\"LTR\"\u003e46\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"8.430913348946136%\" style=\"width: 8.3764%;\"\u003e\n \u003cp dir=\"LTR\"\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.519906323185012%\"\u003e\n \u003cp dir=\"LTR\"\u003e10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"13.348946135831381%\"\u003e\n \u003cp dir=\"LTR\"\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"6.791569086651054%\"\u003e\n \u003cp dir=\"LTR\"\u003e25\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"8.899297423887587%\"\u003e\n \u003cp dir=\"LTR\"\u003e64\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"25.40983606557377%\"\u003e\n \u003cp dir=\"LTR\"\u003eCP+RGO(4)+MoS\u003csub\u003e2\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.627634660421545%\"\u003e\n \u003cp dir=\"LTR\"\u003e\u003cstrong\u003eE\u003csub\u003e5\u003c/sub\u003e\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"5.971896955503513%\" style=\"width: 5.7989%;\"\u003e\n \u003cp dir=\"LTR\"\u003e47\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"8.430913348946136%\" style=\"width: 8.3764%;\"\u003e\n \u003cp dir=\"LTR\"\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.519906323185012%\"\u003e\n \u003cp dir=\"LTR\"\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"13.348946135831381%\"\u003e\n \u003cp dir=\"LTR\"\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"6.791569086651054%\"\u003e\n \u003cp dir=\"LTR\"\u003e25\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"8.899297423887587%\"\u003e\n \u003cp dir=\"LTR\"\u003e73\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"25.40983606557377%\"\u003e\n \u003cp dir=\"LTR\"\u003eCP+RGO(4)+MoS\u003csub\u003e2\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.627634660421545%\"\u003e\n \u003cp dir=\"LTR\"\u003e\u003cstrong\u003eE\u003csub\u003e6\u003c/sub\u003e\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"5.971896955503513%\" style=\"width: 5.7989%;\"\u003e\n \u003cp dir=\"LTR\"\u003e45\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"8.430913348946136%\" style=\"width: 8.3764%;\"\u003e\n \u003cp dir=\"LTR\"\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.519906323185012%\"\u003e\n \u003cp dir=\"LTR\"\u003e0.1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"13.348946135831381%\"\u003e\n \u003cp dir=\"LTR\"\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"6.791569086651054%\"\u003e\n \u003cp dir=\"LTR\"\u003e25\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"8.899297423887587%\"\u003e\n \u003cp dir=\"LTR\"\u003e73.9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"25.40983606557377%\"\u003e\n \u003cp dir=\"LTR\"\u003eCP+RGO(4)+MoS\u003csub\u003e2\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.627634660421545%\"\u003e\n \u003cp dir=\"LTR\"\u003e\u003cstrong\u003eE\u003csub\u003e7\u003c/sub\u003e\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"5.971896955503513%\" style=\"width: 5.7989%;\"\u003e\n \u003cp dir=\"LTR\"\u003e47\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"8.430913348946136%\" style=\"width: 8.3764%;\"\u003e\n \u003cp dir=\"LTR\"\u003e1\u0026micro;l\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.519906323185012%\"\u003e\n \u003cp dir=\"LTR\"\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"13.348946135831381%\"\u003e\n \u003cp dir=\"LTR\"\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"6.791569086651054%\"\u003e\n \u003cp dir=\"LTR\"\u003e25\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"8.899297423887587%\"\u003e\n \u003cp dir=\"LTR\"\u003e74\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"25.40983606557377%\"\u003e\n \u003cp dir=\"LTR\"\u003eCP+RGO(4)+MoS\u003csub\u003e2\u003c/sub\u003e+DNA\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.627634660421545%\"\u003e\n \u003cp dir=\"LTR\"\u003e\u003cstrong\u003eE\u003csub\u003e8\u003c/sub\u003e\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"5.971896955503513%\" style=\"width: 5.7989%;\"\u003e\n \u003cp dir=\"LTR\"\u003e48\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"8.430913348946136%\" style=\"width: 8.3764%;\"\u003e\n \u003cp dir=\"LTR\"\u003e5\u0026micro;l\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.519906323185012%\"\u003e\n \u003cp dir=\"LTR\"\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"13.348946135831381%\"\u003e\n \u003cp dir=\"LTR\"\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"6.791569086651054%\"\u003e\n \u003cp dir=\"LTR\"\u003e25\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"8.899297423887587%\"\u003e\n \u003cp dir=\"LTR\"\u003e74\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"25.40983606557377%\"\u003e\n \u003cp dir=\"LTR\"\u003eCP+RGO(4)+MoS\u003csub\u003e2\u003c/sub\u003e+DNA\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.627634660421545%\"\u003e\n \u003cp dir=\"LTR\"\u003e\u003cstrong\u003eE\u003csub\u003e9\u003c/sub\u003e\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"5.971896955503513%\" style=\"width: 5.7989%;\"\u003e\n \u003cp dir=\"LTR\"\u003e49\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"8.430913348946136%\" style=\"width: 8.3764%;\"\u003e\n \u003cp dir=\"LTR\"\u003e7\u0026micro;l\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.519906323185012%\"\u003e\n \u003cp dir=\"LTR\"\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"13.348946135831381%\"\u003e\n \u003cp dir=\"LTR\"\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"6.791569086651054%\"\u003e\n \u003cp dir=\"LTR\"\u003e25\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"8.899297423887587%\"\u003e\n \u003cp dir=\"LTR\"\u003e74\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"25.40983606557377%\"\u003e\n \u003cp dir=\"LTR\"\u003eCP+RGO(4)+MoS\u003csub\u003e2\u003c/sub\u003e+DNA\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.627634660421545%\"\u003e\n \u003cp dir=\"LTR\"\u003e\u003cstrong\u003eE\u003csub\u003e10\u003c/sub\u003e\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"5.971896955503513%\" style=\"width: 5.7989%;\"\u003e\n \u003cp dir=\"LTR\"\u003e52\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"8.430913348946136%\" style=\"width: 8.3764%;\"\u003e\n \u003cp dir=\"LTR\"\u003e10\u0026micro;l\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.519906323185012%\"\u003e\n \u003cp dir=\"LTR\"\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"13.348946135831381%\"\u003e\n \u003cp dir=\"LTR\"\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"6.791569086651054%\"\u003e\n \u003cp dir=\"LTR\"\u003e25\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"8.899297423887587%\"\u003e\n \u003cp dir=\"LTR\"\u003e74\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"25.40983606557377%\"\u003e\n \u003cp dir=\"LTR\"\u003eCP+RGO(4)+MoS\u003csub\u003e2\u003c/sub\u003e+DNA\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.627634660421545%\"\u003e\n \u003cp dir=\"LTR\"\u003e\u003cstrong\u003eE\u003csub\u003e11\u003c/sub\u003e\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"5.971896955503513%\" style=\"width: 5.7989%;\"\u003e\n \u003cp dir=\"LTR\"\u003enon\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"8.430913348946136%\" style=\"width: 8.3764%;\"\u003e\n \u003cp dir=\"LTR\"\u003e20\u0026micro;l\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.519906323185012%\"\u003e\n \u003cp dir=\"LTR\"\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"13.348946135831381%\"\u003e\n \u003cp dir=\"LTR\"\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"6.791569086651054%\"\u003e\n \u003cp dir=\"LTR\"\u003e25\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"8.899297423887587%\"\u003e\n \u003cp dir=\"LTR\"\u003e74\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"25.40983606557377%\"\u003e\n \u003cp dir=\"LTR\"\u003eCP+RGO(4)+MoS\u003csub\u003e2\u003c/sub\u003e+DNA\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.627634660421545%\"\u003e\n \u003cp dir=\"LTR\"\u003e\u003cstrong\u003eE\u003csub\u003e12\u003c/sub\u003e\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n\u003c/div\u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eTable II:\u0026nbsp;Calculated active surface area for each electrode using the Randles\u0026ndash;Sevĉik equation\u003cspan dir=\"RTL\"\u003e.\u003c/span\u003e\u003c/p\u003e\n\u003cdiv\u003e\n \u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd width=\"59.69924812030075%\" valign=\"top\"\u003e\n \u003cp\u003eActive Surface Area (cm\u0026sup2;)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"40.30075187969925%\" valign=\"top\"\u003e\n \u003cp\u003eModified Electrode\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"59.69924812030075%\" valign=\"top\"\u003e\n \u003cp\u003e0.0076\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"40.30075187969925%\" valign=\"top\"\u003e\n \u003cp\u003eCP\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"59.69924812030075%\" valign=\"top\"\u003e\n \u003cp\u003e0.25\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"40.30075187969925%\" valign=\"top\"\u003e\n \u003cp\u003eCP+RGO\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"59.69924812030075%\" valign=\"top\"\u003e\n \u003cp\u003e0.33\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"40.30075187969925%\" valign=\"top\"\u003e\n \u003cp\u003eCP+RGO+MoS\u003csub\u003e2\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"59.69924812030075%\" valign=\"top\"\u003e\n \u003cp\u003e0.43\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"40.30075187969925%\" valign=\"top\"\u003e\n \u003cp\u003eCP+RGO+MoS\u003csub\u003e2\u003c/sub\u003e+DNA\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n\u003c/div\u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eTable III:\u0026nbsp;A critical comparison of LOD and LDR values for CAP with other reported methods.\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd width=\"13.643659711075442%\"\u003e\n \u003cp\u003e\u003cstrong\u003eMethod\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"31.781701444622794%\"\u003e\n \u003cp\u003e\u003cstrong\u003eElectrode\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"15.569823434991974%\"\u003e\n \u003cp\u003e\u003cstrong\u003eLDR (\u0026micro;M)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"19.582664526484752%\"\u003e\n \u003cp\u003e\u003cstrong\u003eLOD(\u0026micro;M)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"19.42215088282504%\"\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=\"13.643659711075442%\" valign=\"top\"\u003e\n \u003cp\u003eSWV\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"31.781701444622794%\" valign=\"top\"\u003e\n \u003cp\u003eFe3O4@GO@MIP/GCE\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"15.569823434991974%\" valign=\"top\"\u003e\n \u003cp\u003e0.001\u0026ndash;0.1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"19.582664526484752%\" valign=\"top\"\u003e\n \u003cp\u003e3.24\u0026times;10\u003csup\u003e-4\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"19.42215088282504%\"\u003e\n \u003cp\u003e[34]\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"13.643659711075442%\"\u003e\n \u003cp\u003eDPV\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"31.781701444622794%\"\u003e\n \u003cp\u003eAuNPs/SGNF/GCE\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"15.569823434991974%\"\u003e\n \u003cp\u003e0.05-80.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"19.582664526484752%\"\u003e\n \u003cp\u003e0.017\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"19.42215088282504%\"\u003e\n \u003cp\u003e[35]\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"13.643659711075442%\"\u003e\n \u003cp\u003eDPV\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"31.781701444622794%\"\u003e\n \u003cp\u003eZnO/MWCNT/CPE\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"15.569823434991974%\"\u003e\n \u003cp\u003e0.1-100.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"19.582664526484752%\"\u003e\n \u003cp\u003e0.030\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"19.42215088282504%\"\u003e\n \u003cp\u003e[36]\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"13.643659711075442%\"\u003e\n \u003cp\u003eDPV\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"31.781701444622794%\" valign=\"top\"\u003e\n \u003cp\u003eMWCNT-PUFIX/HF-PGE\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"15.569823434991974%\" valign=\"top\"\u003e\n \u003cp\u003e7.70\u0026ndash;142.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"19.582664526484752%\" valign=\"top\"\u003e\n \u003cp\u003e0.11\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"19.42215088282504%\"\u003e\n \u003cp\u003e[37]\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"13.643659711075442%\"\u003e\n \u003cp\u003eDPV\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"31.781701444622794%\"\u003e\n \u003cp\u003eGCE\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"15.569823434991974%\"\u003e\n \u003cp\u003e0.80-50\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"19.582664526484752%\"\u003e\n \u003cp\u003e0.113\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"19.42215088282504%\"\u003e\n \u003cp\u003e[38]\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"13.643659711075442%\"\u003e\n \u003cp\u003eDPV\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"31.781701444622794%\"\u003e\n \u003cp\u003ess-DNA/MoS\u003csub\u003e2\u003c/sub\u003e/RGO/CPE\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"15.569823434991974%\"\u003e\n \u003cp\u003e0.036-60\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"19.582664526484752%\"\u003e\n \u003cp\u003e0.0108\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"19.42215088282504%\"\u003e\n \u003cp\u003eThis work\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e\u0026nbsp;\u003cimg src=\"https://myfiles.space/user_files/122228_c8a1650c59388082/122228_custom_files/img1709745777.png\"\u003e\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e"},{"header":"Schemes","content":"\u003cp\u003eSchemes are available in the Supplementary Files section.\u003c/p\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Capecitabine, Single stranded DNA, DNA biosensor, Carbon paste electrode, Voltammetry","lastPublishedDoi":"10.21203/rs.3.rs-4006078/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-4006078/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eThe present research utilized a simplified procedure for developing a novel electrochemical sensor based on a carbon paste electrode (CPE) modified with single-stranded DNA (ss-DNA), reduced graphene oxide and molybdenum disulfide. Unmodified (bare CPE) and modified (ss-DNA/RGO/MoS\u003csub\u003e2\u003c/sub\u003e/CPE) electrodes were characterized by scanning electron microscopy (SEM), EDX analysis and cyclic voltammetry (CV). Characterization data confirm the good conductivity and electrocatalytic nature with more electrochemically active sites in ss-DNA/RGO/MoS\u003csub\u003e2\u003c/sub\u003e/CPE compared to bare CPE in determination of capecitabine (CAP) analysis in real samples. Two linear ranges have been obtained for the CAP concentration within the ranges of 0.01-10 \u0026micro;M with and 10\u0026ndash;60 \u0026micro;M, with a detection limit of 0.0108 \u0026micro;M and limit of quantification of 0.036 \u0026micro;M. Lower linear concentration range, 0.01-10 \u0026micro;M showed sensitivity of 276.85 AM\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003ecm\u003csup\u003e\u0026minus;\u0026thinsp;2\u003c/sup\u003e, and another from 10 \u0026micro;M to 60 \u0026micro;M with a sensitivity of 5.88 AM\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003ecm\u003csup\u003e\u0026minus;\u0026thinsp;2\u003c/sup\u003e. The performance of the modified electrode was tested in human serum samples and obtained satisfactory recovery results. The selectivity and practical ability of ss-DNA/RGO/MoS\u003csub\u003e2\u003c/sub\u003e/CPE to determine CAP in the presence of different interfering species were investigated. The results show the selective, reliable and accurate response of ss-DNA/RGO/MoS\u003csub\u003e2\u003c/sub\u003e/CPE as CAP electrochemical sensor.\u003c/p\u003e","manuscriptTitle":"A sensitive electrochemical DNA biosensor for determination of Capecitabine anticancer drug based on ss-DNA/RGO/MoS2/CPE electrode","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-03-06 17:24:35","doi":"10.21203/rs.3.rs-4006078/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"c9a86ce8-198e-40fd-9d77-fcc1030765cb","owner":[],"postedDate":"March 6th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2024-03-30T04:29:34+00:00","versionOfRecord":[],"versionCreatedAt":"2024-03-06 17:24:35","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-4006078","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-4006078","identity":"rs-4006078","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}