Enhanced Electrochemical Glucose Sensing via AuNP-Assisted Electrodeposition and Yeast Modification

This study investigates the combined effect of electrodeposited gold nanoparticles (AuNPs) and AuNP–polypyrrole (PPy)-modified Saccharomyces cerevisiae on electrochemical glucose sensing. AuNPs were deposited onto electrode surfaces by cyclic voltammetry, and the resulting interfaces were characterized using atomic force microscopy, cyclic voltammetry, and electrochemical impedance spectroscopy. AFM analysis confirmed increased surface roughness and height variability after deposition, indicating substantial restructuring of the electrode interface. Electrochemical measurements showed that AuNP deposition altered interfacial charge storage and transfer and increased the measured charge-transfer resistance. Glucose sensing was evaluated in a ferricyanide-mediated system using yeast layers with or without AuNP and PPy modification over a 0–60 mM concentration range. All configurations exhibited saturating, non-linear glucose responses described by Hill fitting. Among the evaluated yeast-modified electrodes, the AuNP–PPy modified yeast produced the strongest glucose-induced current increase and the best low-concentration performance, achieving a limit of detection of 0.540 mM, compared with 1.016 mM and 1.330 mM for single-modified layers and 3.360 mM for unmodified yeast. These results show that combining AuNP electrodeposition with AuNP–PPy yeast modification improves interfacial properties and enhances mediator-assisted electrochemical glucose sensing.