Electrochemical stability of screen-printed electrodes modified with Au nanoparticles for detection of methicillin-resistant Staphylococcus aureus

In this study, the surface of carbon screen-printed electrodes (SPEs) was modified with Au nanoparticles (AuNPs) of different sizes to investigate their electrochemical stability for detection of methicillin-resistant Staphylococcus aureus (MRSA). AuNPs were electrochemically synthesised and used to modify the working electrode of SPEs via drop-casting method. Electron microscopic techniques were conducted to investigate the change in the morphology of AuNP-modified SPEs. The electrochemical behaviour of the AuNP-modified SPEs was studied by cyclic voltammetry (CV), differential pulse voltammetry, and electrochemical impedance spectroscopy in 5.0 mM K3 [Fe(CN)6]/K4[Fe(CN)6] solution added with 0.1 M KCl. The AuNP-modified SPEs were also functionalised and prepared for the electrochemical detection of MRSA. Results showed that spherical AuNPs were successfully synthesised, the mean sizes were 25, and 15 nm. The electrochemical behaviour of modified SPEs strongly depended on the size of AuNPs. The AuNP-modified SPEs were stable after 25 CV cycles and can detect MRSA in the range of 10–106 CFU/ml, with a limit of detection (LoD) of 13 CFU/ml. The study revealed that carbon SPEs modified with AuNPs of suitable sizes can provide high-stability in the electrochemical behaviour for biosensing devices, especially for the rapid detection of highly pathogenic microorganisms.