Electrochemical Characterization and Standardization of Nanoparticle-modified Screen-printed Carbon Electrodes for Future Biosensor Applications

A BSTRACT Background: Electrochemical biosensors can analyze biomarkers quickly and accurately. However, surface modification techniques and surface modification materials can affect their working. Aims and Objectives: In this study, three different methods of screen-printed carbon electrode (SPCE) modification were tested and compared. Materials and Methods: Zinc oxide nanoparticles (ZnONPs), gold nanoparticles (AuNPs), and electrodeposited gold were used for SPCE modification. ZnONPs and AuNPs were synthesized and characterized using UV-Vis spectroscopy, FTIR, XRD, DLS, and SEM. ZnONPs and AuNPs were drop-cast on the working electrode of SPCE, while hydrochloroauric acid (HAuCl₄) was used to deposit gold in nanoform via chronoamperometry. All the modified SPCEs were subjected to cyclic voltammetry for assessment and comparison with the bare (unmodified) SPCE. One-way ANOVA with Tukey's post-hoc test was used for statistical analysis. Results: It was found that ZnONP modification performed best at a concentration of 0.75 mg/mL, producing a peak current of 0.29 mA. The undiluted AuNP suspensions did better, reaching 0.45 mA. Among the methods examined, electrodeposited gold, using 20 µM HAuCl₄ solution, delivered the highest peak current of 0.79 mA and the largest electroactive surface area of 0.53 cm². Conclusion: The standardized conditions established herein are expected to serve as a reproducible SPCE platform for future biosensor development. This is particularly relevant for point-of-care detection of clinically relevant biomarkers.