Enzymeless Electrocatalytic Detection of Uric Acid Using Polydopamine/Polypyrrole Copolymeric film

Next-generation of smart dressings: Integrating multiplexed sensors and theranostic functions

Non-healing wounds represent a significant burden for healthcare systems and society, giving rise to severe economic and human issues. Currently, the use of dressings and visual assessment represent the primary and standard care for wounds. Conventional dressings, like cotton gauze, provide only passive physical protection. Besides, they end up paradoxically hampering the wound-healing process by producing tissue damage and pain when removed during routine check-ups. In response to these limitations, researchers, engineers, and technologists are developing innovative dressings that incorporate advanced diagnostic and therapeutic functionalities, coined as "smart dressings". Now, the maturation of smart dressing is bringing them closer to real-life applications, leading to an exciting new generation of these devices. The next generation of smart dressings is capable of monitoring in real-time multiple biomarkers while including pro-healing capabilities in a single platform. Such multiplexed and theranostic smart dressings are expected to offer a timely biomarker-directed diagnosis of non-healing wounds while enabling rapid, automated, and personalized treatments of infection and chronicity. Herein, we provide an insightful overview of these advantageous devices, delving into the diverse spectrum of possible engineering strategies. This encompasses the use of electrochemical and optical platforms with diverse multiplexing architectures, such as multi-zone sensing arrays and multi-layered devices. Open or closed-loop theranostic mechanisms using various stimuli-responsive materials that could be internally or externally controlled are also included. Finally, a critical discussion on the main challenges and future directions of smart dressings is also offered.

Enzymatic and Non-Enzymatic Uric Acid Electrochemical Biosensors: A Review

In recent years, the development of electrochemical biosensors for uric acid has made great achievements. Firstly, uric acid electrochemical biosensors were classified according to their reaction mechanism. Then, the reaction mechanism of the uric acid sensor and the application of nano-modified materials were deeply analyzed from the perspective of non-enzyme and enzymes. In this paper, the catalytic oxidation capacity, enzyme adsorption effect, conductivity, robustness, detection range, and detection limit of uric acid sensors were discussed and compared. Finally, the advantages of acid-sensitive electrochemical biosensors were summarized, and the constructive recommendations were proposed for improving the deficiencies of acid biosensors. The potential for further development in this area was also discussed.

Hybridized sulfated-carboxymethyl cellulose/MWNT nanocomposite as highly selective electrochemical probe for trace detection of arsenic in real environmental samples

A highly selective and ultra-sensitive electrochemical sensing probe was proposed by combining sulfated-carboxymethyl cellulose (CMC-S) and a functionalized-multiwalled carbon nanotube (f-MWNT) nano-composite with high conductivity and durability. The CMC-S/MWNT nanocomposite was impregnated on a glassy carbon electrode (GCE) to construct the non-enzymatic and mediator-free electrochemical sensing probe for trace detection of As(iii) ions. The fabricated CMC-S/MWNT nanocomposite was characterized by FTIR, SEM, TEM, and XPS. Under the optimized experimental conditions, the sensor exhibited the lowest detection limit of 0.024 nM, a high sensitivity (69.93 μA nM-1 cm-2) with a good linear relationship in the range of 0.2-90 nM As(iii) concentration. The sensor demonstrated strong repeatability, with the current response continuing at 84.52% after 28 days of use, in addition to good selectivity for the determination of As(iii). Additionally, with recovery ranging from 97.2% to 107.2%, the sensor demonstrated comparable sensing capability in tap water, sewage water, and mixed fruit juice. The electrochemical sensor for detecting trace levels of As(iii) in actual samples is anticipated to be produced by this effort and is expected to possess great selectivity, good stability, and sensitivity.

Polypyrrole-induced active-edge-S and high-valence-Mo reinforced composites with boosted electrochemical performance for the determination of 2,4,6-trichlorophenol in the aquatic environment

With the extensive application of halogenated aromatic compounds, including 2,4,6-Trichlorophenol (2,4,6-TCP), improper treatment or discharge contribute to persistently harmful effects on humans and the ecosystem, rendering the identification and monitoring of 2,4,6-TCP in the aquatic environment urgently required. In this study, a highly sensitive electrochemical platform was developed using active-edge-S and high-valence-Mo rich MoS₂/polypyrrole composites. MoS₂/PPy illustrates superior electrochemical performance and catalytic activity and has not been explored for detecting chlorinated phenols previously. The local environment of polypyrrole induces the richness of active edge S and a high oxidation state of Mo species in the composites, both of which endorse a sensitive anodic current response due to the favored oxidation of 2,4,6-TCP through nucleophilic substitution. Also, the higher complementarity between pyrrole and 2,4,6-TCP with respective electron-rich and electron-poor features through π-π stacking interactions enhances the specific detection capability of 2,4,6-TCP by the MoS₂/polypyrrole-modified electrode. The MoS₂/polypyrrole-modified electrode achieved a linear range of 0.1-260 μM with an ultralow limit of detection of 0.009 μM. Additionally, the structural stability boosted by the linkage of polypyrrole and MoS₂ results in good resistance and satisfactory recovery in real water samples. The compiled results demonstrate that the proposed MoS₂/polypyrrole composite opens up a new potential to advance a sensitive, selective, facile fabrication, and low-cost platform for the on-site determination of 2,4,6-TCP in aquatic systems. The sensing of 2,4,6-TCP is important to monitor its occurrence and transport, and can also serve to track the effectiveness and adjust subsequent remediation treatments applied to contaminated sites.

Facile Approach to Fabricate Oriented Porous PDMS Composites for Movements Monitoring and Identifying Motion Patterns

The facile and rapid fabrication of oriented porous polymers is crucial for flexible pressure sensors. Herein, a pressure sensor is developed based on oriented porous polydimethylsiloxane (PDMS) composites for detecting human motion and identifying joint motion patterns. The oriented porous PDMS composite is first constructed through thiol-ene click chemistry and directional freezing within only 30 min, then fabricated by interfacial in situ polymerization of dopamine and pyrrole to generate robust interfaces. As a result, the as-prepared oriented porous PDMS composite is assembled into a pressure sensor that shows potential applications in pressure and human motion detection. Interestingly, a sensor assembled by orthogonally stacking the PDMS composites can be used for joint motion pattern recognition with potential monitoring of football motion due to their directional structures. This facile strategy coupled with the oriented porous structure is expected to help design advanced wearable electronic devices.

Recent progress and future perspectives of polydopamine nanofilms toward functional electrochemical sensors

Since its discovery in 2007, polydopamine nanofilms have been widely used in many areas for surface functionalization. The simple and low-cost preparation method of the nanofilms with tunable thickness can incorporate amine and oxygen-rich chemical groups in virtually any interface. The remarkable advantages of this route have been successfully used in the field of electrochemical sensors. The self-adhesive properties of polydopamine are used to attach nanomaterials onto the electrode's surface and add chemical groups that can be explored to immobilize recognizing species for the development of biosensors. Thus, the combination of 2D materials, nanoparticles, and other materials with polydopamine has been successfully demonstrated to improve the selectivity and sensitivity of electrochemical sensors. In this review, we highlight some interesting properties of polydopamine and some applications where polydopamine plays an important role in the field of electrochemical sensors.

Sensitive and Rapid Detection of Aspartic Acid with Co3O4-ZnO Nanorods Using Differential Pulse Voltammetry

Herein, the detection of aspartic acid by doped Co₃O₄-ZnO nanorod materials was proposed using differential pulse voltammetry. The nano-composite metal oxide was synthesized by the wet precipitation method in basic media. Aspartic acid is a non-essential amino acid naturally synthesized in the body with lot of health significance, including as a biomarker for several health deficiencies. The synthesized composite Co₃O₄-ZnO nanorod was well-investigated by using FESEM, XRD, XPS, FTIR, UV/vis., EIS, and CV. The synthesized composite exhibited a low limit of detection (0.03 µM, high sensitivity (0.0014 µA µM^-1 cm^-2) and wide linear range (0.05-50 µM) for aspartic acid. The substrate, the Co₃O₄-ZnO nanorod, enhanced the electro-catalytic oxidation of aspartic acid as a result of its catalytic and conductivity properties. The developed sensor based on Co₃O₄-ZnO has a repeatable, reproducible and stable current response for aspartic acid. Additionally, other electroactive compounds did not interfere with the sensor's current response. The suitability of the developed sensor for real sample analysis was also established. Therefore, this study proposed the potential use of Co₃O₄-ZnO nanorod material in healthcare management for the maintenance of human well-being.

Sensitivity Detection of Uric Acid and Creatinine in Human Urine Based on Nanoporous Gold

Given the significance of uric acid and creatinine in clinical diagnostic, disease prevention and treatment, a multifunctional electrochemical sensor was proposed for sensitive detection of uric acid and creatinine. The sensitive detection of uric acid was realized based on the unique electrochemical oxidation of nanoporous gold (NPG) towards uric acid, showing good linearity from 10 μM to 750 μM with a satisfactory sensitivity of 222.91 μA mM−1 cm−2 and a limit of detection (LOD) of 0.06 μM. Based on the Jaffé reaction between creatinine and picric acid, the sensitive detection of creatinine was indirectly achieved in a range from 10 to 2000 μM by determining the consumption of picric acid in the Jaffé reaction with a detection sensitivity of 195.05 μA mM−1 cm−2 and a LOD of 10 μM. For human urine detection using the proposed electrochemical sensor, the uric acid detection results were comparable to that of high-performance liquid chromatography (HPLC), with a deviation rate of less than 10.28% and the recoveries of uric acid spiked in urine samples were 89~118%. Compared with HPLC results, the deviation rate of creatinine detection in urine samples was less than 4.17% and the recoveries of creatinine spiked in urine samples ranged from 92.50% to 117.40%. The multifunctional electrochemical sensor exhibited many advantages in practical applications, including short detection time, high stability, simple operation, strong anti-interference ability, cost-effectiveness, and easy fabrication, which provided a promising alternative for urine analysis in clinical diagnosis.

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.

Ultrasensitive Picomolar Detection of Aqueous Acids in Microscale Fluorescent Droplets

We report on a fluorescent-droplet-based acid-sensing scheme that allows limits of detection below 100 pM for weak acids. The concept is based on a strong partitioning of acid from an aqueous phase into octanol droplets. Using salicylic acid as a demonstration, we show that at a high concentration, the acid partitions into the organic phase by a factor of 260, which is approximately consistent with literature values. However, at lower concentrations, we obtain a partition coefficient as high as 10⁶, which is partly responsible for the excellent sensing performance. The enhanced equilibrium partitioning is likely due to the interaction of the dissociated acid phase with the sensor dye employed for this work. The effect of droplet size was determined, after which we derived a simple model to predict the time dependence of the color change as a function of droplet size. This work shows that color-change fluorescent-droplet-based detection is a promising avenue that can lead to exceptional sensing performance from an aqueous analyte.

A highly efficient electrochemical sensor containing polyaniline/cerium oxide nanocomposites for hydrogen peroxide detection

An efficient electrochemical sensor containing (PANI/CeO2) for the detection of hydrogen peroxide has been fabricated using the in situ oxidative polymerization. The fabricated electrode sensor was successfully used to detect H2O2 in real samples.

Comparison of a 2D/3D imidazole-based MOF and its application as a non-enzymatic electrochemical sensor for the detection of uric acid

Two dimensional microplate of W-ZIF-67 promotes a high catalytic activity for non-enzymatic electrochemical uric acid detection.

The fast nucleation/growth of Co3O4 nanowires on cotton silk: the facile development of a potentiometric uric acid biosensor

In this study, we have used cotton silk as a source of abundant hydroxyl groups for the fast nucleation/growth of cobalt oxide (Co₃O₄) nanowires via a hydrothermal method. The crystal planes of the Co₃O₄ nanowires well matched the cubic phase. The as-synthesized Co₃O₄ nanowires mainly contained cobalt and oxygen elements and were found to be highly sensitive towards uric acid in 0.01 M phosphate buffer solution at pH 7.4. Importantly, the Co₃O₄ nanowires exhibited a large surface area, which was heavily utilized during the immobilization of the enzyme uricase via a physical adsorption method. The potentiometric response of the uricase-immobilizing Co₃O₄ nanowires was measured in the presence of uric acid (UA) against a silver/silver chloride (Ag/AgCl) reference electrode. The newly fabricated uric acid biosensor possessed a low limit of detection of 1.0 ± 0.2 nM with a wide linear range of 5 nM to 10 mM and sensitivity of 30.6 mV dec⁻¹. Additionally, several related parameters of the developed uric acid biosensor were investigated, such as the repeatability, reproducibility, storage stability, selectivity, and dynamic response time, and these were found to be satisfactory. The good performance of the Co₃O₄ nanowires was verified based on the fast charge-transfer kinetics, as confirmed via electrochemical impedance spectroscopy. The successful practical use of the uric acid biosensor was demonstrated based on the recovery method. The observed performance of the uricase-immobilizing Co₃O₄ nanowires revealed that they could be considered as a promising and alternative tool for the detection of uric acid under both in vitro and in vivo conditions. Also, the use of cotton silk as a source of abundant hydroxyl groups may be considered for the remarkably fast nucleation/growth of other metal-oxide nanostructures, thereby facilitating the fabrication of functional electrochemical devices, such as batteries, water-splitting devices, and supercapacitors.

In this study, we have used cotton silk as a source of abundant hydroxyl groups for the fast nucleation/growth of cobalt oxide (Co₃O₄) nanowires via a hydrothermal method.

Development of L-cysteine sensor based on thallium oxide coupled multi-walled carbon nanotube nanocomposites with electrochemical approach

Here, Nanocomposites of thallium oxide doped multi-walled carbon nanotube (Tl2O.MWCNT NCs) were prepared by utilizing the wet-chemical method (WCM) in an alkaline phase at low temperature. Different optical procedures (FTIR: Fourier Transform Infra-Red Spectroscopy, XRD: Powder X-ray diffraction, FESEM: Field-Emission Scanning Electron Microscopy, XEDS: X-ray Electron Dispersive Spectroscopy, TEM: Tunneling Electron Microscopy, and XPS: X-ray photoelectron spectroscopy) were used to fully characterize (Optical, structural, crystalline, morphological, and elemental etc.) of the prepared Tl2O.MWCNT NCs. Modification of the thin-layer with NCs onto glassy carbon electrode (GCE) is prepared and applied for the enzyme-free detection of selective and sensitive L-cysteine by electrochemical approach. Using a reliable current-voltage approach, analytical sensing indexes such as sensitivity, LDR, LOD, LOQ, durability, and interference were assessed by fabricated sensor probe (GCE/Tl2O.MWCNT NCs/CPM) in selective detection of L-cysteine in a room condition, whereas nafion was used as conducting polymer matrix (CPM) during the fabrication of GCE with NCs. L-cysteine calibration plot was found to be linear over an extensive range of concentration. The calibration curve was used to calculate the sensing parameters such as sensitivity (316.46 pAμM-1cm-2), LOD down to (~18.90 ± 1.89 pM), and LOQ (63.0 pM) of the prepared sensor. The use of a simple WCM to validate the Tl2O.MWCNT NCs is a good approach for developing a NCs-based sensor for enzyme-free biomolecule identification and detection in the biomedical and health care fields in a broad scale. This proposed sensor (GCE/Tl2O.MWCNT NCs/CPM) is used to detect selective L-cysteine in real biological samples such as human, mouse, and rabbit serum and found acceptable and satisfactory results.

Development of Methanol Sensor Based on Sol-Gel Drop-Coating Co3O4·CdO·ZnO Nanoparticles Modified Gold-Coated µ-Chip by Electro-Oxidation Process

Herein, novel Co₃O₄·CdO·ZnO-based tri-metallic oxide nanoparticles (CCZ) were synthesized by a simple solution method in basic phase. We have used Fourier Transform Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Field Emission Scanning Electron Microscope (FESEM), Dynamic Light Scattering (DLS), Tunneling Electron Microscopy (TEM), and Energy-Dispersive Spectroscopy (EDS) techniques to characterize the CCZ nanoparticles. XRD, TEM, DLS, and FESEM investigations have confirmed the tri-metallic nanoparticles’ structure, while XPS and EDS analyses have shown the elemental compositions of the CCZ nanoparticles. Later, a Au/μ-Chip was modified with the CCZ nanoparticles using a conducting binder, PEDOT: PSS (poly(3,4-ethylenedioxythiophene) polystyrene sulfonate) in a sol-gel system, and dried completely in air. Then, the CCZ/Au/μ-Chip sensor was used to detect methanol (MeOH) in phosphate buffer solution (PBS). Outstanding sensing performance was achieved for the CCZ/Au/μ-Chip sensor, such as excellent sensitivity (1.3842 µAµM⁻¹cm⁻²), a wide linear dynamic range of 1.0 nM–2.0 mM (R² = 0.9992), an ultra-low detection limit (32.8 ± 0.1 pM at S/N = 3), a fast response time (~11 s), and excellent reproducibility and repeatability. This CCZ/Au/μ-Chip sensor was further applied with appropriate quantification results in real environmental sample analyses.

Novel Aminosilane (APTES)-Grafted Polyaniline@Graphene Oxide (PANI-GO) Nanocomposite for Electrochemical Sensor

Lead is a potentially toxic element (PTE) that has several adverse medical effects in humans. Its presence in the environment became prominent due to anthropogenic activities. The current study explores the use of newly developed composite materials (organic-inorganic hybrid) based on PANI-GO-APTES for electrochemical detection of Pb²⁺ in aqueous solution. The composite material (PANI-GO-APTES) was synthesized by chemical method and was characterized with SEM, XPS, XEDS, XRD, TGA, FTIR, EIS and CV. The result of characterization indicates the successful synthesis of the intended material. The PANI-GO-APTES was successfully applied for electrochemical detection of Pb²⁺ using cyclic voltammetry and linear sweep voltammetry method. The limit of detection of Pb²⁺ was 0.0053 µM in the linear range of 0.01 µM to 0.4 µM. The current response produced during the electrochemical reduction of Pb²⁺ catalyzed by PANI-GO-APTES was also very repeatable, reproducible and rapid. The application of PANI-GO-APTES-modified GCE in real sample analysis was also established. Therefore, PANI-GO-APTES is presented as a potential Pb²⁺ sensor for environmental and human health safety.

E-Tongues/Noses Based on Conducting Polymers and Composite Materials: Expanding the Possibilities in Complex Analytical Sensing

Conducting polymers (CPs) are extensively studied due to their high versatility and electrical properties, as well as their high environmental stability. Based on the above, their applications as electronic devices are promoted and constitute an interesting matter of research. This review summarizes their application in common electronic devices and their implementation in electronic tongues and noses systems (E-tongues and E-noses, respectively). The monitoring of diverse factors with these devices by multivariate calibration methods for different applications is also included. Lastly, a critical discussion about the enclosed analytical potential of several conducting polymer-based devices in electronic systems reported in literature will be offered.

Molecular Imprinting Technology for Determination of Uric Acid

The review focuses on the overview of electrochemical sensors based on molecularly imprinted polymers (MIPs) for the determination of uric acid. The importance of robust and precise determination of uric acid is highlighted, a short description of the principles of molecular imprinting technology is presented, and advantages over the others affinity-based analytical methods are discussed. The review is mainly concerned with the electro-analytical methods like cyclic voltammetry, electrochemical impedance spectroscopy, amperometry, etc. Moreover, there are some scattered notes to the other electrochemistry-related analytical methods, which are capable of providing additional information and to solve some challenges that are not achievable using standard electrochemical methods. The significance of these overviewed methods is highlighted. The overview of the research that is employing MIPs imprinted with uric acid is mainly targeted to address these topics: (i) type of polymers, which are used to design uric acid imprint structures; (ii) types of working electrodes and/or other parts of signal transducing systems applied for the registration of analytical signal; (iii) the description of the uric acid extraction procedures applied for the design of final MIP-structure; (iv) advantages and disadvantages of electrochemical methods and other signal transducing methods used for the registration of the analytical signal; (vi) overview of types of interfering molecules, which were analyzed to evaluate the selectivity; (vi) comparison of analytical characteristics such as linear range, limits of detection and quantification, reusability, reproducibility, repeatability, and stability. Some insights in future development of uric acid sensors are discussed in this review.

Photocatalytic, anti-bacterial performance and development of 2,4-diaminophenylhydrazine chemical sensor probe based on ternary doped Ag·SrSnO3 nanorods

Ag·SrSnO₃ NRs is an excellent photocatalyst, kills both Gram positive and Gram negative bacteria. The 2,4-DAPHyd sensor fabricated by layered Ag·SrSnO₃ NRs onto GCE shows high sensitivity (7.5854 μA μM⁻¹ cm⁻²); LDR, 0.1 nM~0.01 mM & LOD, 96.13 ± 4.81 pM.

Single-Atom Cobalt-Based Electrochemical Biomimetic Uric Acid Sensor with Wide Linear Range and Ultralow Detection Limit

Uric acid (UA) detection is essential in diagnosis of arthritis, preeclampsia, renal disorder, and cardiovascular diseases, but it is very challenging to realize the required wide detection range and low detection limit. We present here a single-atom catalyst consisting of Co^(II) atoms coordinated by an average of 3.4 N atoms on an N-doped graphene matrix (A-Co-NG) to build an electrochemical biomimetic sensor for UA detection. The A-Co-NG sensor achieves a wide detection range over 0.4-41,950 μM and an extremely low detection limit of 33.3 ± 0.024 nM, which are much better than previously reported sensors based on various nanostructured materials. Besides, the A-Co-NG sensor also demonstrates its accurate serum diagnosis for UA for its practical application. Combination of experimental and theoretical calculation discovers that the catalytic process of the A-Co-NG toward UA starts from the oxidation of Co species to form a Co³⁺-OH-UA*, followed by the generation of Co³⁺-OH + ^*UA_H, eventually leading to N-H bond dissociation for the formation of oxidized UA molecule and reduction of oxidized Co³⁺ to Co²⁺ for the regenerated A-Co-NG. This work provides a promising material to realize UA detection with wide detection range and low detection limit to meet the practical diagnosis requirements, and the proposed sensing mechanism sheds light on fundamental insights for guiding exploration of other biosensing processes.

CuO Hollow Cubic Caves Wrapped with Biogenic N-Rich Graphitic C for Simultaneous Monitoring of Uric Acid and Xanthine

Herein, we synthesized hollow cubic caves of CuO (HC) and wrapped it with N-rich graphitic C (NC), derived from a novel biogenic mixture composed of dopamine (DA) and purine. The synthesized NC wrapped HC (NC@HC) sensor shows enhanced electrocatalytic efficacy compared to unwrapped CuO with shapes including HC, sponge (SP), cabbage (CB), and solid icy cubes (SC). The shape and composition of synthesized materials were confirmed through field-emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS), whereas interfacial surface energy was calculated through contact angle measurement. The designed NC@HC sensor shows a remarkable response toward the simultaneous detection of uric acid (UA) and xanthine (Xn) with detection limits of 0.017 ± 0.001 (S/N of 3) and 0.004 ± 0.001 μM (S/N of 3), respectively. In addition, this platform was successfully applied to monitor UA from the gout patient serum. To the best of our knowledge, this is the first report on using such novel NC@HC materials for the simultaneous monitoring of UA and Xn.

Polymers and Plastics Modified Electrodes for Biosensors: A Review

Polymer materials offer several advantages as supports of biosensing platforms in terms of flexibility, weight, conformability, portability, cost, disposability and scope for integration. The present study reviews the field of electrochemical biosensors fabricated on modified plastics and polymers, focusing the attention, in the first part, on modified conducting polymers to improve sensitivity, selectivity, biocompatibility and mechanical properties, whereas the second part is dedicated to modified "environmentally friendly" polymers to improve the electrical properties. These ecofriendly polymers are divided into three main classes: bioplastics made from natural sources, biodegradable plastics made from traditional petrochemicals and eco/recycled plastics, which are made from recycled plastic materials rather than from raw petrochemicals. Finally, flexible and wearable lab-on-a-chip (LOC) biosensing devices, based on plastic supports, are also discussed. This review is timely due to the significant advances achieved over the last few years in the area of electrochemical biosensors based on modified polymers and aims to direct the readers to emerging trends in this field.

Homopolymerization of 3-aminobenzoic acid for enzyme-free electrocatalytic assay of nitrite ions

We describe non-enzymatic novel detection of nitrite ions in various matrices on the surface of poly-3-aminobenzoic acid.