Design and fabrication of polymer-based cytocompatible surface coating

Abstract

Advance of materials science and technologies is highly based on the development of polymeric surface engineering. Functional versatility, controllable structure, and economic efficiency of polymer have expanded its application to diverse field of material surface engineering. Substrate properties can be controlled with diverse surface modification techniques including surface-initiated polymerization (SIP), polyphenol coating, and layer-by-layer assembly (LbL). They build additional surface layer to the material, for introducing new polymeric characters which did not originally have. In recent research, the importance of cytocompatiblity in polymer coating is getting higher since the surface modification of biomaterials (protein, virus, and living cell) is widely applied in bio-nanotechnology. Especially in cell surface engineering, the chemical vulnerability in living cells requires the tailored design of cytocompatible surface coating. In this thesis, various polymeric surface coating have been designed for cytocompatible surface modification. Four different strategies were firstly optimized with flat substrates, and applied for single-cell nanoencapsulation: (1) Surface-initiated atom transfer radical polymerization (SI-ATRP) was developed for the modification of living yeast surfaces with dopamine-based ATRP initiator. In this work, activators regenerated by electron transfer (ARGET) ATRP was used for reducing the amount of toxic copper catalyst, and proceeding reaction in aerobic conditions. Polydopamine ATRP initiator not only initiated radical polymerization, but also protect cell against radical ion which is produced during reaction. Dense polymer shell of yeast prevented agglutination when they are mixed with E.coli, and impeded cell division. (2) Plant-derived pyrogallol (1,2,3-trihydroxybenezene) coating was optimized for encapsulation of various cell types (yeast, HeLa, human red blood cells). Polymerization of the pyrogallol was proceeded with weak based (pH 7.8) isotonic solution, showing high cytocompatibility. The shell also blocked antigen-antibody coagulation of hRBC according to blood types. (3) Enzymatic polymerization inspired by melanogenesis was applied for versatile film formation. Tyrosinase accelerated polymerization and deposition of various phenolic amines (tyrosine, tyramine, dopamine, norepinephrine, and DOPA) in neutral condition. The strategy is fast and efficient, and forms uniform film compared with previous polydopamine coating. Extremely high cytocompatibility of the method also allow the film deposition onto living Jurkat cell surfaces without any noticeable decrease in viability. (4) Coffee melanoidins was utilized for material-independent coating. Catechol moiety of the melanoidin strongly bind with ferric ion, inducing supramolecular complexation and deposition. The film can additionally be modified with ring-opening polymerization, biomimetic silicification, and functionalized with poly-L-lysine for neural interface. In addition, cytointerfacial reaction was applied for the fabrication of coffee melanoidin shell onto living cell surface, and post-modified with silica.