High‐Performance Flexible Nonenzymatic Uric Acid Biosensor Based on Cu‐Doped Polyaniline–Graphene Nanocomposite

The demand for polymers with antibacterial properties is increasing in food packaging industry and medical supplies. Antibacterial additives without toxic metal ion release are crucial for health and safety but still have challenges. Herein, polypropylene (PP) nanocomposite was prepared with polyaniline/graphene nanocomposite (PANI/GNP) as a green antibacterial additive due to its electrostatic, free radical, and nanoknife effect synergistic antibacterial mechanisms. To improve the dispersibility of PANI/GNP, nanosilica coating on PANI/GNP was constructed successfully with in situ condensation polymerization of epoxy functionalized ethyl orthosilicate to obtain EP‐nSiO2‐PANI/GNP. EP‐nSiO2‐PANI/GNP with a thin nanosilica coating has a significantly improved thermal stability as compared with that of PANI/GNP characterized by TGA. The EP‐nSiO2‐PANI/GNP presents a nanoscale disperse state in PP nanocomposite and thus enhances the melt viscosity and storage modulus accordingly characterized by TEM and Rheology. The EP‐nSiO2‐PANI/GNP/PP filled with 0.5 wt% of EP‐nSiO2‐PANI/GNP demonstrates antibacterial activity of 100% against both Escherichia coli and Staphylococcus aureus.Highlights In situ condensation polymerization to prepare EP‐nSiO2‐PANI/GNP. EP‐nSiO2‐PANI/GNP has enhanced dispersion stability. EP‐nSiO2‐PANI/GNP with a thin nanosilica coating has a good thermal stability. PP nanocomposite with 0.5 wt% filler has excellent antibacterial activity. The electrostatic, free radical, and nanoknife effect antibacterial mechanism.

A portable aptasensor for facile personalized monitoring of serum uric acid

Dopamine, a critical neurotransmitter involved in regulating nervous and immune system responses, is essential for maintaining overall health. Abnormal dopamine levels are linked to neurodegenerative diseases such as Alzheimer’s and Parkinson’s. Accurate measurement of dopamine, particularly in blood where other interfering substances like uric acid and ascorbic acid are present, is crucial. This study focuses on developing a selective and sensitive electrochemical method for dopamine detection using Fe3O4-activated carbon electrodes derived from pyrolyzed spent coffee grounds. The prepared electrodes exhibit enhanced stability and electrocatalytic properties due to the synergistic effects of high surface area, oxygen-containing species, and the catalytic properties of Fe3O4. Detailed characterization of the Fe3O4-activated carbon composite was conducted using XRD, SEM, FTIR, and cyclic voltammetry, confirming the successful incorporation of Fe3O4 and the presence of functional groups essential for redox reactions. The modified electrodes demonstrated significant improvements in dopamine detection, achieving a detection limit of 0.92 µM with a linear range of 1 - 1,325 µM, and effectively minimizing interference from ascorbic acid and uric acid. The practicality of the developed method was validated through successful dopamine detection in a human serum sample, highlighting its potential for real-world applications in clinical diagnostics. HIGHLIGHTS The study presents a sustainable method for creating a sensitive and selective electrode for dopamine detection by using Fe3O4-activated carbon derived from spent coffee grounds. The use of coffee grounds adds value to a waste material and supports sustainable practices. The composite of magnetic activated carbon derived from coffee grounds was characterized using FE-SEM, FTIR, XRD, and electrochemical techniques. The electrode demonstrated excellent performance in dopamine detection. It achieved a low detection limit of 0.92 µM and a wide linear detection range of 1 - 1,325 µM. These values are comparable to those of other modified electrodes. Electrochemical characterization of the Nafion coating on the electrode revealed that it slightly slowed the diffusion of the detecting species but did not significantly hinder the electrode response. The use of Nafion also helped to reduce interference from ascorbic acid and uric acid. GRAPHICAL ABSTRACT

Wearable sensors have gained much attention due to their potential in personal health monitoring in a timely, cost-effective, easy-operating, and noninvasive way. In recent studies, nanomaterials have been employed in wearable sensors to improve the sensing performance in view of their excellent properties. Here, focus is mainly on the nanomaterial-enabled wearable sensors and their latest advances in personal health monitoring. Different kinds of nanomaterials used in wearable sensors, such as metal nanoparticles, carbon nanomaterials, metallic nanomaterials, hybrid nanocomposites, and bio-nanomaterials, are reviewed. Then, the progress of nanomaterial-based wearable sensors in personal health monitoring, including the detection of ions and molecules in body fluids and exhaled breath, physiological signals, and emotion parameters, is discussed. Furthermore, the future challenges and opportunities of nanomaterial-enabled wearable sensors are discussed.

Analyte mediated transformation of metasurface: A dual-mode plasmonic sensing platform for uric acid.

Flexible electrochemical uric acid and glucose biosensor

In this study, luffa peel extract was employed to investigate its impact on the morphology, particle size, surface properties, optical band gap, and surface active sites of nickel oxide (NiO). Various analytical techniques revealed that the synthesized NiO nanostructures, prepared using 2 ml of luffa peel extract, exhibited a distinctive flower-like morphology, the smallest particle size, abundant surface oxygen vacancies, the narrowest optical band gap, and enhanced surface catalytic activity. The electrochemical non-enzymatic method demonstrated significant efficiency in oxidizing uric acid (UA) in phosphate buffer solution at pH 7.3, utilizing sample 3 of the NiO nanostructures. Sample 3 exhibited a broad linear detection range for UA, spanning from 0.1 mM to 15 mM, along with an exceptionally low limit of detection of 0.004 mM, as determined through chronoamperometry. Furthermore, sample 3 of NiO was found to be highly stable, reproducible, and selective. Non-enzymatic UA sensors were successfully applied to quantify UA levels in blood and urine samples, yielding highly accurate results with a relative standard deviation of less than 3%. This research highlights the potential of luffa peel extract in the development of a diverse range of electrocatalytic materials for applications in clinical diagnostics, biomedical research, and related fields.

Nano‐octahedron cobalt oxide decorated graphene nanocomposite is reported in this work for selective and simultaneous determination of dopamine (DA) and uric acid (UA). The composite is synthesized using a hydrothermal method and characterized to identify the crystal structure and its shapes. The Scanning Electron Microscope (SEM) and Transmission Electron Microscope (TEM) images indicate the silhouette image of the nanocube decorated over graphene oxide. The Gr‐Co₃O₄/glassy carbon electrode (GCE) is utilized for the electrochemical detection of dopamine (DA). Cyclic voltammetry (CV) studies revealed a significant breakthrough such as Gr‐Co₃O₄/GCE exhibited higher electrocatalytic activity for DA oxidation than the bare GCE. Differential pulse voltammetry (DPV) measurements demonstrated a detection limit of 0.09 µM for DA, with a linear response range from 1 to 500 µM. For uric acid (UA), the detection limit and linear range are estimated as 0.2 and 100 to 8000 µM, respectively. The sensor selectively detects DA in the presence of UA is confirmed, with a peak separation of 250 mV between DA and UA. The reliability of the sensor is validated through using human serum specimens, paving the way for exciting potential applications in biomedical research and clinical diagnostics.

A modified electrode was prepared by modification of the carbon paste electrode (CPE) with a nanostructured material. This nanostructure with electrocatalytic activity was synthesized by combination of poly pyrrole and copper oxide nanoparticles (PPy/CuO). The structure and morphology of PPy/CuO was studied. The fabricated modified electrode (CPE‐PPy/CuO) exhibited an excellent electrocatalytic activity toward levodopa (L‐DOPA) and uric acid (UA) oxidation because of high conductivity, low electron transfer resistance and catalytic effect. The CPE‐PPy/CuO had a lower overvoltage and enhanced electrical current with respect to the bare CPE for both L‐DOPA and UA. Also, the modified electrode showed a good resolution for the overlapped anodic peaks of L‐DOPA and UA. This electrode was used for the successful simultaneous determination of L‐DOPA and UA. The electrochemical sensor responded to L‐DOPA and UA in the concentration range of 0.050–1200 μM and 0.040–2000 μM, respectively. The detection limits were obtained by differential pulse voltammetry as 15 nM for L‐DOPA and 20 nM for UA. Finally, the proposed electrode was used for determination of L‐DOPA and UA in real samples using standard addition method.

Non-woven fabrics based on Nylon 6/carbon black-graphene nanoplatelets obtained by melt-blowing for adsorption of urea, uric acid and creatinine

Highly sensitive and selective dopamine sensing in biological fluids with one-pot prepared graphene/poly(o-phenylenediamine) modified electrodes

Overoxidized poly(3,4-ethylenedioxythiophene)–gold nanoparticles–graphene-modified electrode for the simultaneous detection of dopamine and uric acid in the presence of ascorbic acid

Au@MOF-199 functionalized graphene oxide nanocomposite for simultaneous electrochemical detection of dopamine and uric acid.

Au-IDA microelectrodes modified with Au-doped graphene oxide for the simultaneous determination of uric acid and ascorbic acid in urine samples

The aromatic amino acids tyrosine (TY) and tryptophan (TP) are important as precursors of catecholamines and 5-hydroxytryptamine. An innovative strategy was proposed in preparation of a novel layered sensor based on layer-by-layer modification of a glassy carbon electrode surface (GC) with graphene (RGO), ionic liquid crystal (ILC), multi-walled carbon nanotubes (CNT) and Fe–Zn nano-alloy (GC/RGO/ILC/CNT/Fe–Zn). The conductive layered electrode offered good sensitivities and low detection limit values for determination of tyrosine (TY) and tryptophan (TP) due to the synergistic impact of its components. A major problem expected during electrochemical assays of TY or TP in human biological fluids is overlap of their current responses with ascorbic acid (AA) and uric acid (UA) compounds when using the unmodified electrodes. Thus, the proposed sensor resolved this problem and exhibited excellent electrocatalytic activity towards determination of TY or TP in presence of AA and UA in human serum with low detection limit values 5.1 nM, 86 nM, 2.6 nM for TY, AA and UA and 3.8 nM, 91 nM, 2.9 nM for TP, AA and UA, respectively. Moreover, the proposed sensor displayed good sensitivity towards simultaneous determination of dopamine (DA) and serotonin (ST) with TY or TP. Recovery tests of TY and TP compounds were successful.