Uric Acid Sensor Research Articles

Transition metal complex-incorporated polyaniline as a platform for an enzymatic uric acid electrochemical sensor.

Uric acid (UA) is the primary waste product from purine metabolism in humans. Excessive UA levels in the body will accumulate in joints and form crystals that cause a wide range of health problems. An enzymatic electrochemical biosensor for UA based on the transition metal complex-incorporated polyaniline PANI-RC functionalized with both urate oxidase (UOx) as a specific bioreceptor and horseradish peroxidase (HRP) as a signal enhancer was developed. The transition metal complex being used herein is the commonly used redox couple (RC) in electrochemical biosensors, [Fe(CN)6]3-/4-, which plays the pivotal role of electron acceptors. This PANI-RC platform then becomes a conducive environment not only for enzyme immobilization but also for signal transfer improvement. The synergistic combination of HRP near UOx and RC anchored on the backbone of PANI helps in electron transfer from the enzymatic reaction to the current collector. The resulting PANI-RC-based UA sensor demonstrates high sensitivity with a detection limit of 11.4 μM, wide linear range, good stability, and excellent selectivity even in the presence of the most problematic interference in UA assays (e.g., ascorbic acid and urea). The recovery tests using artificial biofluid-spiked UA samples also showed promising results for practical usage of the PANI-RC-based UA sensor.

Hexagonal cobalt oxide nanosheet-based enzymeless electrochemical uric acid sensor with improved sensitivity

A hexagonal cobalt oxide nanosheet based enzymeless electrochemical sensor showed an ultra-sensitive response for uric acid with excellent selectivity.

Enzyme-free and wide-range portable colorimetric sensing system for uric acid and hydrogen peroxide based on copper nanoparticles

Uric acid (UA) is the final product of purine metabolism. A high concentration of UA in body fluid may lead to kidney stones, gout, and some cardiovascular diseases. Therefore, the non-invasive daily monitoring of UA is of great significance for both hyperuricemia patients and fit people. However, most of the current detection methods for UA are enzyme-dependent which limits the application scenarios and lacks portable instruments for on-site detection, including optics and electrochemistry. In this work, an enzyme-free and wide-range colorimetric sensor for UA and H2O2 detection was developed based on a mercaptosuccinic acid (MSA)-modified Cu nanoparticles (CuNPs). Under the action of UA or H2O2, with the cleavage of MSAs on the CuNPs surface, small Cu particles are further aggregated into larger particles with a lightning violet color. With the employment of the multi-channel handheld automatic photometer (MHAP), the concentration of UA and H2O2 can be determined on-site according to the absorbance measurement by the photodiodes. The linear range of UA was 5 μM-4.5 mM with the limit of detection (LOD) of 3.7 μM, while the linear range of H2O2 was 5 mM–500 mM and 5 μM-5 mM with the LOD of 4.3 μM. This approach has been applied to the detection of UA in human urine, providing more possibilities for non-invasive home health monitoring, community medical diagnosis, and broader prospects of on-site disease detection.

Electrochemical Ultrasensitive Sensing of Uric Acid on Non-Enzymatic Porous Cobalt Oxide Nanosheets-Based Sensor

Transition metal oxide (TMO)-based nanomaterials are effectively utilized to fabricate clinically useful ultra-sensitive sensors. Different nanostructured nanomaterials of TMO have attracted a lot of interest from researchers for diverse applications. Herein, we utilized a hydrothermal method to develop porous nanosheets of cobalt oxide. This synthesis method is simple and low temperature-based. The morphology of the porous nanosheets like cobalt oxide was investigated in detail using FESEM and TEM. The morphological investigation confirmed the successful formation of the porous nanosheet-like nanostructure. The crystal characteristic of porous cobalt oxide nanosheets was evaluated by XRD analysis, which confirmed the crystallinity of as-synthesized cobalt oxide nanosheets. The uric acid sensor fabrication involves the fixing of porous cobalt oxide nanosheets onto the GCE (glassy carbon electrode). The non-enzymatic electrochemical sensing was measured using CV and DPV analysis. The application of DPV technique during electrochemical testing for uric acid resulted in ultra-high sensitivity (3566.5 µAmM-1cm-2), which is ~7.58 times better than CV-based sensitivity (470.4 µAmM-1cm-2). Additionally, uric acid sensors were tested for their selectivity and storage ability. The applicability of the uric acid sensors was tested in the serum sample through standard addition and recovery of known uric acid concentration. This ultrasensitive nature of porous cobalt oxide nanosheets could be utilized to realize the sensing of other biomolecules.

Eggshell nano-CaCO3 decorated PANi/rGO composite for sensitive determination of ascorbic acid, dopamine, and uric acid in human blood serum and urine

A novel and green method of extraction of nano-sized CaCO 3 from white chicken eggshells, its characterization and application for electrochemical sensing of ascorbic acid, dopamine, and uric acid has been described. XRD analysis showed that the average size of the nano-CaCO 3 particles extracted was 32.3 ± 14.7 nm (α, 12) and match with the calcite phase. The best peak separation for the three analytes found when its composite with PANi and rGO was in 1:1:1 ratio. The nano-CaCO 3 based sensor was able to detect all the three analytes in raw blood sample, showed excellent selectivity and LODs 10.81 µM, 0.01 µM and 0.04 µM respectively for ascorbic acid, dopamine and uric acid. The capability of the extraction process to control the size of CaCO 3 in a perfect nanometer range and the significant role played by nano-CaCO 3 in resolving the oxidation peaks of the three typical analytes expected to impact significantly the future sensor research through substitution of the costly and hazardous nanomaterials. • A green reagentless method of extraction of nano-CaCO 3 demonstrated • Eggshell nano-CaCO 3 based sensor for ascorbic acid dopamine and uric acid developed. • The sensor can detect all the three analytes in raw blood sample. • Excellent selectivity towards ascorbic acid, dopamine and uric acid achieved.

Terahertz Enhanced Sensing of Uric Acid Based on Metallic Slot Array Metamaterial.

An enzyme-free terahertz uric acid sensor based on a metallic slot array metamaterial was proposed and realized both theoretically and experimentally. The sensing model was verified in simulation and femtosecond laser processing technology was employed to ablate slots in the copper plate to fabricate metamaterials. Analytes were tested with liquid phase deposition on the metamaterial by a terahertz frequency domain spectroscopy system. Gradient concentrations of uric acid, ascorbic acid, and a mixture of them were measured separately with a good linear response. A significant decrease in sensitivity was observed in the ascorbic acid assay compared with the uric acid assay. The test results of the mixture also proved that our device is resistant to ascorbic acid. It is a simple and effective method for monitoring uric acid concentrations and the strategy of eliminating interference while modulating the resonance peak location mentioned here can be rationally projected for the development of other sensors.

A nonenzymatic uric acid sensor based on electrophoretically deposited Graphene/ITO electrode

AbstractA nonenzymatic uric acid sensor is proposed based on an electrophoretically deposited Graphene/ITO electrode (EDG). The morphology and structure of the EDGs were characterized by scanning electron microscopy (SEM) and Raman spectroscopy. As a result, the EDGs electrode was successfully fabricated with a well‐adhered graphene film on the ITO substrate surface. The electrochemical properties of the EDG for uric acid were investigated in PBS buffer pH 7.4, using cyclic voltammetry (CV) studies. Quantification of uric acid using both cyclic scanning and differential addition polarization methods. As a result, the uric acid sensor has a linear range from 1 to 100 μM, sensitivity 318.4 (μAcm2mM‐1) from CV measurements. Moreover, by the differential pulse voltammetry (DPV), the sensor has a linear range from 1 to 50 μM, a sensitivity of 1242.7 (μAcm2 mM‐1), and the detection limit (LOD) of 0.6 μM (S/N = 3). The oxidation peak potential separation of uric acid, ascorbic, and dopamine at the EDG electrode showed that the uric sensor could eliminate interferences (ascorbic acid, dopamine) and be used to simultaneously determine uric acid, ascorbic acid, and dopamine.

Morphological and elemental tuning of BiOCl/BiVO4 heterostructure for uric acid electrochemical sensor and antibiotic photocatalytic degradation

Deep eutectic solvents (DES) consisting of EG-(ChCl: C2H6O2) and TU-(ChCl: CH4N2S) assisted synthesized BiOCl/BiVO4 heterostructured catalyst studied for electrochemical uric acid (UA) sensor and tetracycline photocatalytic degradation. The chemical composition of the BiOCl/BiVO4 catalyst was analyzed by X-ray photoelectron spectroscopy (XPS). UV–vis spectroscopy reveals increased absorption of visible light till the near-infrared region, which results in a narrowing of band gap energy from 2.3 eV to 2.2 eV for BiOCl/BiVO4-TU. Morphology of catalyst analyzed using field-emission scanning electron microscope (FE-SEM) and Transmission electron microscope (TEM) technique. Time-Resolved photoluminescence (TRPL) confirms an increased lifetime of e−/h+ pair after heterostructure formation. The catalyst-modified glassy carbon electrode shows selectivity toward the detection of uric acid (UA). The limit of detection (LOD) is estimated to be 0.04688 μM for UA; also, interference and stability of catalyst were studied. Photocatalytic activity of the synthesized catalyst was investigated by degrading tetracycline (TC) antibiotic pollutants, and their intermediate product was analyzed by ion trap mass spectrometry (MS).

Electrochemical fabrication of Co(OH)2 nanoparticles decorated carbon cloth for non-enzymatic glucose and uric acid detection.

Cobalt hydroxide nanoparticles (Co(OH)2 NPs) were uniformly deposited on flexible carbon cloth substrate (Co(OH)2@CC) rapidly by a facile one-step electrodeposition, which can act as an enzyme-free glucose and uric acid sensor in an alkaline electrolyte. Compositional and morphological characterization were examined by X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS), which confirmed the deposited nanospheres were Co(OH)2 nanoparticles (NPs). The electrochemical oxidation of glucose and uric acid at Co(OH)2@CC electrode was investigated by electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), differential pulse voltammetry (DPV), and chronoamperometry methods. The results revealed a remarkable electrocatalytic activity toward the single and simultaneous determination of glucose and uric acid at about 0.6 V and 0.3V (vs. Ag/AgCl), respectively, which isattributed to a noticeable synergy effect between Co(OH)2 NPs and CC with good repeatability, satisfactory reproducibility, considerable long-term stability, superior selectivity, outstanding sensitivity, and wide linear detection range from 1 uM to 2mM and 25nM to 1.5 uM for glucose and UA, respectively. The detection limits were 0.36nM for UA and 0.24μM for glucose (S/N = 3). Finally, theCo(OH)2@CC electrode was utilized for glucose and uric acid determination in human blood samples and satisfying results were obtained. The relative standard derivations (RSDs) for glucose and UA were in the range 6 to 14% and 0 to 3%, respectively. The recovery ranges for glucose an UA were 97 to 103% and 95 and 101%, respectively. These features make the novel Co(OH)2@CC sensor developed by a low-cost, efficient, and eco-friendly preparation method apotentially practical candidate for application to biosensors.

A Novel Uric Acid Biosensor Based on Regular Prussian Blue Nanocrystal/ Upright Graphene Oxide Array Nanocomposites

Background: Uric acid (UA) is an important metabolic intermediate of the human body. Abnormally high levels of UA will cause diseases. However, UA monitoring with commercial products relies on invasive blood collection, which not only causes pain in patients but also risks bacterial infections and skin irritation. In recent years, new models of noninvasive detection through body surface penetration have raised higher expectations for the sensitivity of uric acid detection, and rapid, accurate and highly sensitive UA sensors will become powerful tools for the diagnosis of UA-related diseases. Objective: This study aimed to identify the differences in catalytic efficiency between regular PB from spray crystallization (RPB) and irregular PB from electrodeposition (EDPB), which is used for fabricate a high sensitive uric acid sensor. Method: Regular Prussian blue nanocrystals (RPB) were grown on graphene oxide flakes (GO), on the surface of a custom screen-printed carbon electrode (SPCE), using a spray method assisted by a constant magnetic field (CMF). After immobilizing uricase, the uric acid biosensor Uricase/RPB/CMF-GO/SPCE was obtained. Result: The detection range of the sensor response to UA was 0.005~2.525 mM, and the detection limit was as low as 3.6 μM. The cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) results showed that compared to amorphous electrodeposited Prussian blue (EDPB), RPB more favorably accelerated electron transport. Conclusion: This novel uric acid biosensor exhibits high sensitivity over a wide concentration range, strong anti-interference ability, and good stability and reproducibility. Thus, it has good application prospects for determining uric acid in physiological samples.

Salivary uric acid sensor using the fordable “Finger‐Powered” microfluidic device

AbstractHere, we report a novel biosensing system using a finger‐powered microfluidic device, which is suitable for daily self‐testing of uric acid in saliva. To realize the rapid determination of salivary uric acid, the biosensing system measures directly from the paper‐based saliva sampling device. The microfluidic device has the diaphragm pump, the reagent reservoir, and the reaction cell in which the electrochemical uric acid biosensor is embedded. Once the microfluidic chip has been folded, the finger‐powered microfluidic device prepares the reagent containing the saliva, which is ready to measure. A wireless potentiostat for electrochemical measurement of uric acid with the biosensor was also developed. Combining these elements together, the whole process from saliva sampling to determination was completed in less than a minute (Sensitivity: 0.03 nA/μM). The measurement results were also consistent with that measured using a commercially available uric acid determination kit. Hence, our method is expected to have the potential to enhance the use of biochemical information in the field of healthcare IoT.

An Electrochemical-Based Point-of-Care Testing Methodology for Uric Acid Measurement.

Point-of-care technology (POCT) is an important method in clinical testing in the future, which can achieve the purpose of rapid analysis. In this work, we assembled an electrochemical POC sensor for uric acid (UA) by surface modification of a screen-printed electrode. Copper nanowires were used as electrode modifiers to achieve high-performance electrochemical oxidation of UA. This electrochemical sensor can achieve linear detection of UA in the range of 10 μM to 2 mM. The detection limit of the sensor was calculated to be 2 μM. Although the detection performance of this sensor is not competitive with high-performance electrochemical sensors, it has been able to meet the needs of POC detection. At the same time, the sensor has excellent anti-interference performance. It has also been used successfully to test urine and serum samples from healthy and gout patients.

Development of a Nonenzymatic Colorimetric Sensor for the Detection of Uric Acid Based on Ionic Liquid-Mediated Nickel Nanostructures.

Uric acid (UA) is a metabolic byproduct of purine nucleotides and is excreted as a urine component. Abnormalities in UA metabolism cause localized inflammation due to crystal deposition and can lead to various diseases. In the current study, we successfully fabricated a biosensor based on 1-H-3-methylimidazolium acetate (ionic liquid, IL)-capped nickel nanoparticles (NiNPs) for the detection of uric acid in test samples. The structures of IL-capped NiNPs and their precursors were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, and X-ray diffraction. The IL-capped NiNPs possessed intrinsic peroxidase-like properties and displayed selective UA quenching after interacting with 3,3′,5,5′-tetramethylbenzidine (TMB) solution. Different parameters such as pH, time, IL, TMB, and UA concentration were optimized to obtain the best results for the proposed sensor. The UA biosensor shows good responses in the linear range from 1 × 10–8 to 2.40 × 10–6 M, with a lower limit of detection of 1.30 × 10–7 M, a limit of quantification of 4.3 × 10–7 M, and an R2 value of 0.9994. For the colorimetric detection of UA, the proposed sensor gave a short time response of 4 min at room temperature and pH 7.5. The proposed sensing probe detects UA in real serum samples and could be used as a selective sensor for UA in the real sample detection.

Electrochemical detection of uric acid in undiluted human saliva using uricase paper integrated electrodes

In this study, we introduce a uricase-immobilized paper (UOx­-paper) integrated electrochemical sensor for detection of uric acid (UA) in saliva. The UOx was immobilized on the detection zone in the wax-patterned paper substrate. This UOx-paper was integrated with a Prussian blue­-modified, screen-printed carbon electrode after electropolymerization of o-phenylenediamine to construct an electrochemical cell for small-volume (20 μL) of samples. First, we optimized the fabrication conditions of UOx-paper. Next, the amperometric response of the UOx-paper-based electrochemical UA sensor was analyzed using a known concentration of UA standard solution in artificial saliva at an applied potential of − 0.1 V (versus Ag pseudo-reference electrode). The UOx-­paper based electrochemical UA sensor showed a sensitivity of 4.9 μA·mM−1 in a linear range of 50 to 1000 μM (R2 = 0.998), high selectivity and good reproducibility, as well as a limit of detection of 18.7 μM (0.31 mg/dL) UA. Finally, we quantified the UA levels in undiluted saliva samples of healthy controls (n = 20) and gout patients (n = 8). The levels were correlated with those measured with conventional salivary UA enzymatic assays as well as serum UA levels. The UOx-paper-based electrochemical UA sensor is a user-friendly and convenient tool to assess salivary UA levels.

(Digital Presentation) Novel Porous Functionalized Mwcnts-TiO2/g-C3N4 heterostructure Modified Screen Printed Electrode for a Rapid Enzyme-Free Detection of Uric Acid in Human Urine

Porous heterostructures gained wide appreciation for their escalated sensing performance in electrochemical society. In the present work, we report the porous functionalized MWCNTS-TiO2/g-C3N4 (f-MWTGCN) heterostructure modified screen-printed electrode for the detection of uric acid in human urea samples. The f-MWTGCN are synthesized via a two-step combination process by hydrothermal-assisted ultrasonication construction. The fabricated powders are subjected to X-Ray diffraction to identify the size, structure, dislocation densities, and micro strain. The morphological studies are performed by the FESEM and HRTEM analysis to identify the confinement of heterostructures. The required chemical analysis was obtained from the FTIR and Raman studies and substantiated the qualitative and quantitative vibrational modes. The obtained highly porous ultrafine powders are drop cast on the screen-printed electrode to modify the working electrode to achieve super ultrafast sensing. Functionalization of MWCNTs facilitated the carbon to attain hydroxyl, carboxyl, and carbonyl functional groups which assisted in the rapid detection of uric acid. The reproducibility and stability of the electrode were evaluated by the fifteen repeated cyclic voltammetry responses to 0.1M uric acid. The developed sensors showcased a detection of Limit (DoL) of 1.17 µM and sensitivity of 98.1 nA µM-1 with a range of two to three seconds. The utilization of the developed heterostructure for modifying screen-printed electrodes and sensing uric acid is a unique and novel approach. Thus, the fabricated highly stable sensor may be utilized as the uric acid sensor in biomedical applications. Keywords: Porous, Heterostructures, Functionalized MWCNTS, Reproducibility, and Hydrothermal.

Modification of screen-printed carbon electrode (SPCE) by the Nafion functionalized silicon nanoparticles (SiNP/Naf) materials in non-enzymatic electrochemical sensor for uric acid (UA) detection

A non-enzymatic electrochemical sensor has been successfully developed to detect uric acid (UA) based on a modified screen-printed carbon electrode (SPCE) using Nafion functionalized silicon nanoparticles. Silicon nanoparticles (SiNPs) material is used because of their advantages, including its abundant availability, good biocompatibility, and adjustable porosity and surface area according to the synthesis method used. Nafion is a sulfonated tetrafluoroethylene-based fluoropolymer-copolymer that has been widely used for electrochemical sensors and is functioned as a stabilizer of the sensor. In this study, SiNPs material was successfully synthesized through the non-thermal chemical vapor deposition method. XRD diffractogram and SEM image confirmed its structure and morphology. The crystallinity of the produced SiNPs is 69.85%. SEM-EDS characterization was also carried out to confirm the success of the SPCE modification by SiNPs and SiNPs/Naf materials. The changes in the morphology of SPCE and the EDS spectrum that were measured indicated the success of the SPCE modification process for each stage. Cyclic voltammetry, electrochemical impedance spectroscopy, and differential pulse voltammetry study were used to analyze the electrochemical characteristics and performance of non-enzymatic electrochemical sensors based on SPCE/SiNPs/Naf structures against uric acid analytes. Based on the results of electrochemical analysis, the sensitivity, detection limit, and quantification limit of the sensor are 0.01 μA.mM-1. cm-2, 0.21 μM, and 0.69 μM respectively in the linear measurement range of uric acid concentration of 10 – 1000 μM. Then, a sensor stability study was also carried out which resulted in an RSD value of 4.83%.

An Efficient Enzyme-Less Uric Acid Sensor Development Based on PbO-Doped NiO Nanocomposites.

Here, the voltammetric electrochemical approach was applied to detect uric acid (UA) in a conductive sensing medium (phosphate buffer solution-PBS) by using PbO-doped NiO nanocomposites (NCs)-decorated glassy carbon electrode (GCE) performing as working electrode. The wet-chemically prepared PbO-doped NiO NCs were subjected to characterization by the implementation of XRD, FESEM, XPS, and EDS analysis. The modified GCE was used to detect uric acid (UA) in an enzyme-free conductive buffer (PBS) of pH = 7.0. As the outcomes of this study reveal, it exhibited good sensitivity of 0.2315 µAµM−1cm−2 and 0.2233 µAµM−1cm−2, corresponding to cyclic (CV) and differential pulse (DPV) voltammetric analysis of UA, respectively. Furthermore, the proposed UA sensor showed a wider detection (0.15~1.35 mM) range in both electrochemical analysis methods (CV & DPV). In addition, the investigated UA sensor displayed appreciable limit of detection (LOD) of 41.0 ± 2.05 µM by CV and 43.0 ± 2.14 µM by DPV. Good reproducibility performance, faster response time and long-time stability in detection of UA were perceived in both electrochemical analysis methods. Finally, successful analysis of the bio-samples was performed using the recovery method, and the results were found to be quite acceptable in terms of accuracy. Thus, the findings indicate a reliable approach for the development of 5th generation biosensors using metal-oxides as sensing substrate to fulfill the requirements of portable use for in situ detection.

Sensitive and selective electrochemical determination of uric acid in urine based on ultrasmall iron oxide nanoparticles decorated urchin-like nitrogen-doped carbon

Hypercrosslinked pyrrole was synthesized via the Friedel–Crafts reaction and then carbonized to obtain urchin-like nitrogen-doped carbon (UNC). Ultrasmall iron oxide nanoparticles were then supported on UNC, and the composite was used to prepare an electrochemical sensor for detecting uric acid (UA) in human urine. FexOy/UNC was characterized and analyzed via scanning electron microscopy, transmission electron microscopy, energy dispersive spectrometry, X-ray diffraction, and X-ray photoelectron spectroscopy. A glassy carbon electrode (GCE) modified with FexOy/UNC was used as an electrochemical sensor to effectively identify UA. The electrochemical behavior of the FexOy/UNC-based UA sensor was studied using differential pulse stripping voltammetry, and the optimal conditions were determined by changing the amount of FexOy/UNC, pH of the buffer solution, deposition potential, and deposition time. Under optimal conditions, the FexOy/UNC-based electrochemical sensor detected UA in the range of 2–200 μM, where the limit of detection (LOD) for UA was 0.29 μM. Anti-interference experiments were performed, and the sensor was applied to the actual analysis of human urine samples. Urea, glucose, ascorbic acid, and many cations and anions present at 100-fold concentrations relative to UA did not strongly interfere with the response of the sensor to UA. The FexOy/UNC electrochemical sensor has high sensitivity and selectivity for uric acid in human urine samples and can be used for actual clinical testing of UA in urine.

Functionalized Iron Oxide Nanostructures: Recent Advances in the Synthesis, Characterization, and Electrochemical Biosensor Applications

FBiosensors play a significant role in the process of early diagnosis of non-communicable disease. In the global market, biosensors are valued at over 25.5 billion USD in 2021. Screen Printed Electrodes were traditionally used for biomolecule detection, but due to their poor stability and low conducting properties, they have been replaced by Glassy Carbon Electrodes, which exhibit excellent stability and reusability, only few works have been reported in glucose detection. The objective of this review is to provide an overview on the synthesis iron oxide nanoparticles and their composites developed for the electrochemical applications by various research works. The iron oxide and their composites of suitable morphologies at nanoscale dimensions prepared by various methods and conditions were compiled. The characterization results of all the samples obtained by X-Ray Diffraction, Scanning Electron Microscopy, Fourier Transform Infrared Spectroscopy, and Raman Spectroscopy were discussed in detail. The sensing efficiency of nanoscale iron oxides, when they are functionalized/combined with carbon nanotube, polyamidoamine dendrimer, Cellulose Nanocrystals, Terephthalic acid, Polyaniline, etc. were discussed in detail. The requirement for the development of more suitable electrochemical sensors for glucose, ascorbic acid, dopamine, and uric acid were proposed. The most suitable functionality for the iron oxide to is proposed for the development of efficient electrochemical sensor. Finally, the review provides the summary of the iron oxide nanomaterials, current challenges, and future scope of electrochemical sensors.

A facile electrochemical sensor based on a composite of electrochemically reduced graphene oxide and a PEDOT:PSS modified glassy carbon electrode for uric acid detection.

A glassy carbon electrode modified with electrochemically reduced graphene oxide (ErGO) and poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) was developed for uric acid determination with dopamine as interference in artificial saliva. The electrochemical performance of the fabricated electrode was studied using both techniques of cyclic voltammetry (CV) and differential pulse voltammetry (DPV), under optimized conditions. Using DPV, the sensor based on ErGO/PEDOT:PSS modified GCE displayed a linear relationship in the concentration ranges of 10-100µM for uric acid. This uric acid sensor exhibited a high sensitivity with detection limits of 1.08µM and quantitation limit of 3.61µM. This sensor also showed good reproducibility for uric acid detection in artificial saliva in 5 consecutive days of measurements. This device was successfully used to analyze uric acid in artificial saliva as well as in a human saliva sample using the standard addition method.