Thiol Reactive Maleimido-Containing Tannic Acid for the Bioinspired Surface Anchoring and Post-Functionalization of Antifouling Coatings

Inspired by tea stains, a new surface anchor, maleimido-containing tannic acid (TAMA), was developed to introduce the maleimido functionality onto stainless steel (SS) surfaces. The feasibility of maleimido groups to serve as anchoring sites for surface functionalization via Michael addition was explored in a model experiment using thiol-containing 1H,1H,2H,2H-perfluorodecanethiol. The surface conjugation efficiency of TAMA with the thiol-containing compounds via Michael addition was also compared to that of the surface with tannic acid (TA) only. Water-soluble thiolated carboxymethyl chitosan (CMCSSH) was then grafted on the SS surface preanchored with TAMA via solution immersion and spin coating. The deposition of CMCSSH was characterized by contact angle measurement, surface zeta potential, and X-ray photoelectron spectroscopy (XPS). The antifouling efficacy of the CMCSSH coatings was evaluated by protein adsorption and bacterial adhesion. The cytotoxic effect of the CMCSSH coatings on mammalian cells was evaluated using the standard 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay with 3T3 fibroblasts.