One-Pot Synthesis of a Zwitterionic Small Molecule Bearing Disulfide Moiety for Antibiofouling Macro- and Nanoscale Gold Surfaces

The goal of this study is to develop a simple one-pot method for the synthesis of a zwitterionic small molecule bearing disulfide moiety, which can effectively inhibit nonspecific protein adsorption on macroscopic and nanoscopic gold surfaces. To this end, the optimal molecular structure of a pyridine disulfide derivative was explored and a zwitterionic small molecule was successfully synthesized from the tertiary amine residue on the pyridine ring through a one-pot method. The coating conditions of the synthesized zwitterionic molecules on the gold surface were optimized through contact angle measurements, and the strong interactions between the gold surface and the disulfide moiety of the zwitterion small molecule were confirmed by surface plasmon resonance (SPR) analysis and X-ray photoelectron spectroscopy. The antibiofouling properties of the coated gold surface were analyzed by fluorescence microscopic observations after contacting with FITC-labeled bovine serum albumin (BSA) and SPR sensor as contacting with BSA solution. In addition, the effect of zwitterion-coating on the salt stability of and protein adsorption on nanoscopic gold surfaces were examined through a NaCl stability test and BSA adsorption test, respectively. From the obtained results, it was confirmed that the simply synthesized zwitterionic small molecule was effective in inhibiting nonspecific protein adsorption on macroscopic and nanoscopic gold surfaces; further, it enhanced the salt stability of gold nanoparticle surfaces.