Surface Regeneration of Gold-Coated Chip for Highly-Reproducible Surface Plasmon Resonance Immunoassays

Abstract

We developed a simple procedure for the complete regeneration of silane-grafted gold surface. This method allowed the reuse of the regenerated gold chip for custom refunctionalization. In addition, we performed highly reproducible immunoassays using these chips over several cycles. The developed procedure was optimized and comprised of consecutive treatments of functionalized Au chip with 12 M HCl for 10 min and 29 W oxygen (O2)- plasma for 5 min. Monitoring and surface characterization of the developed methodology was performed with ellipsometry and Rutherford back scattering. The developed procedure was demonstrated on SPR-based Human Fetuin A (HFA) immunoassay, where the amino groups of APTES-functionalized Au chip were cross linked to the carboxyl groups of anti-HFA antibody using 1-ethyl-3-[3-dimethylaminopropyl] carbodiimide hydrochloride and sulfo- N-hydroxy succinimide. The APTES-functionalization, anti-HFA antibody immobilization and HFA binding on the regenerated SPR Au chip were highly reproducible over 40 HFA immunoassay cycles.