Zwitterionic Surface Modification of Aldehydated Sulfobetaine Copolymers for the Formation of Bioinert Interfaces

This research successfully developed a zwitterionic copolymer, poly(2-oxoethyl methacrylate- co -sulfobetaine methacrylate) poly(OxMA- co -SBMA), in which the OxMA segments have an aldehyde functional group that can undergo a nucleophilic addition reaction with an amine group to generate a Schiff base. At the same time, SBMA units are employed as antifouling groups. This copolymer is grafted via a graft-to process to the surface of an amine-based substrate to form chemical bonds by dip-coating technology and achieves antifouling properties. The synthesized monomer and copolymers are characterized by Fourier transform infrared (FTIR) spectroscopy and NMR to confirm their chemical structure. Notably, dip-coating technology uses a simple “ graft-to ” immersion process to achieve nonfouling and antiprotein properties. Compared to the previously reported ″ graft-from ″ technology, dip-coating has the advantage of a fast and simple procedure and is easy to scale up. The poly(OxMA- co -SBMA) copolymer was grafted onto the amino substrate surface by controlling the dip-coating conditions of different grafting temperatures, grafting time, concentrations of copolymer solution, and copolymer molar ratios. The prepared poly(OxMA- co -SBMA) with an optimum pOxMA/pSBMA molar ratio of 1:4 and a molecular weight of 46.8 kDa exhibited an improvement of hydrophilicity and the best resistance to protein adsorption with over 90% reduction, as well as blood cell activation, tissue cell adhesion, and bacterial attachment on the zwitterionic copolymer-grafted surfaces. The results showed that the modified samples under the best grafting conditions could effectively reduce the biofouling of biomolecules. Meanwhile, it performed well in modified amine-based plastic materials, such as polyurethane tubes and polyamide bending fabrics, which are expected to have broader bioinert application potential in biomedical materials.