Abstract:
Undesired biofouling is always considered as one of the most important factors that affects the efficiency, durability, or even the workability of materials applied in biomedical and industrial field, including biosensors, implant devices, drug delivery carriers, filtration membranes, marine vessels, and so on. To address this issue, it is quite necessary to develop fouling-resistant materials by introducing antifouling polymers on surface. Zwitterionic polymers, based on carboxybetaine, sulfobetaine or phosphorylcholine, are widely applied in surface modification to obtain nonfouling materials due to their unique biological antifouling properties. The traditional surface modification strategies, including "graft to" and "graft from", both involve sophisticated functionalization of surface. Only pretreated surfaces with anchoring groups or initiators that allow the antifouling polymers for durable modification. Therefore, the design of a simple and effective surface modification method is of great significance to the materials resisting nonspecific protein adsorption. Inspired by the strong adhesion of mussel protein, dopamine, the crucial component for adhesion, is chosen as an anchoring group that can tightly bind to the substrate without surface chemical specificity. In this work, the catechol (DOPA) group with great adhesion and poly(sulfubetaine methacrylate) (PSBMA) with excellent protein resistance properties were conjugated together to obtain an adhesive zwitterionic polymer DOPA-PSBMA to be used as the antifouling surface modifier. DOPA-PSBMA was successfully synthesized by an atomic transfer radical polymerization (ATRP) method. DOPA-PSBMA is a temperature-responsive polymer with an upper critical solution temperature of 22-35℃. DOPA-PSBMA was successfully attached on the surface of hydroxylated silicon substrate from polymer solution dipping at room temperature, which can be proved by the X-ray photoelectron spectroscopy (XPS). Thus, the antifouling properties of the silicon substrates were greatly improved after attachment of DOPA-PSBMA. From both laser scanning confocal microscopy (LSCM) and ELISA technique, the antifouling properties of the pristine and DOPA-PSBMA modified substrates were compared. The modified silicon substrates had good resistance to protein adsorption performance under 37℃ and 4℃, indicating that the antifouling properties of DOPA-PSBMA modified surface was temperature-insensitive. The facile method to modify substrate surfaces to be antifouling by the DOPA-PSBMA solution dipping will be of great potential application in surface engineering and biomaterial science.