Systematic Nonenzymatic Glucose Detection Using Hydrogel-Protected Ag-Cu/MWCNTs Nanocomposites

The growing need for reliable and selective glucose monitoring has accelerated interest in nonenzymatic electrochemical sensors. In this work, we introduce a high-performance sensor based on silver-copper (Ag-Cu) alloy nanoparticles uniformly anchored onto multiwalled carbon nanotubes (MWCNTs), further enhanced with a polymeric protective layer composed of polyvinylpyrrolidone (PVP) and poly-(vinyl alcohol) (PVA). The materials were synthesized via a hydrothermal process, and the atomic ratio of Ag/Cu was precisely tuned. Among all compositions, the Ag₅-Cu₅ configuration exhibited the highest electrocatalytic activity, attributed to a strong bimetallic synergistic effect and the excellent conductivity of the MWCNTs framework. Cyclic voltammetry and amperometry measurements confirmed that the sensor achieved a sensitivity of 237.2 μA·mM^-1·cm^-2, a detection limit of 1.2 μM, and a linear response range spanning from 0.5 to 10 mM. The PVP/PVA hydrogel coating improved selectivity by acting as a molecular sieve, excluding interfering species like uric acid (UA) and ascorbic acid (AA) through electrostatic repulsion while allowing neutral glucose to diffuse freely. The integration of metal alloy nanostructures with hydrogel interface engineering offers a robust strategy for real-time glucose sensing in complex biofluids such as blood and sweat, advancing the development of next-generation nonenzymatic glucose sensors.