AN EVALUATION OF A GOLD SURFACE FUNCTIONALIZATION PROCEDURE FOR ANTIBODY BINDING AND PROTEIN DETECTION USING 11-MERCAPTOUNDECANOIC ACID (11-MUA)

Immunosensors play an essential role in biological element recognition systems. Among the numerous types of electrodes utilized for immunosensor, gold electrodes with surface modification have attracted considerable attention and have experienced various improvements and developments due to their advantages, compromising high conductivity and chemical stability. Self-assembled monolayer (SAM) has been used as an effective approach for biomarker immobilization onto electrodes. In this study, two types of gold electrodes, namely, sputtered gold on a glass slide and screen-printed gold electrodes, were utilized to assess the performance of the proposed procedure utilizing 11-Mercaptoundecanoic acid (11-MUA). Bovine serum albumin-fluorescein isothiocyanate conjugate (BSA-FITC) and anti-albumin antibody (anti-BSA) were employed as the antigen-antibody pair. Microscope-based fluorescent, Raman spectroscopy and electrical measurements, including cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), were conducted to validate the success of each step in the surface functionalization process. The results showed that BSA proteins were immobilized on the modified electrode, as indicated by the fluorescent green color observed under the microscope and the changes in surface impedance recorded in Raman spectroscopy, CV and EIS signal graphs. Additionally, the influence of the 11-MUA incubation time and the protein concentration on the performance of the gold electrode surface functionalization process were investigated. The results indicate that an incubation time exceeding 24 h and a protein concentration of 5 mu M was found to be the most optimal conditions. The screen-printed gold electrode exhibited a slightly superior performance in comparison to the sputtered gold electrode. This work has verified the proposed gold surface functionalization process and can serve as a solid foundation for future immunosensor research studies.