Surface macromolecular microarchitecture design:: Biocompatible surfaces via photo-block-graft-copolymerization using N,N-diethyldithiocarbamate

The photo-block-graft-copolymerzation method using an iniferter, benzyl N,N-diethyldithiocarbamate, was utilized to design a biomedically functional surface for fabricated devices. Ultraviolet light irradiation under sequential charge of vinyl monomers, such as acrylic acid (AA), n-butyl methacrylate (BMA), N,N-dimethylacrylamide (DMAAm), N-[3-(dimethylamino)propyl] acrylamide (DMAPAAm), or styrene (ST), produced block-grafted surfaces, in which different polymer blocks were sequentially formed on polyST (PST) partially derivatized with N,N-diethyldithiocarbamate groups. Examination of a cross-sectional view under a transmission electron microscope (TEM) revealed a bilayered structure of the PST-b-PDMAAm block-graft copolymer. Three different AB-type block-graft-copolymerized surfaces were prepared for biomedical applications, where block A was the bottom layer and block B the top layer: (1) For heparin immobilization, a polyPDMAPAAm (PDMAPAAm) (A)-polyDMAAm (PDMAAm) (B) block-graft-copolymerized surface was prepared, where the block A layer contained ionically immobilized heparin and the block: B layer functioned as a protective layer to suppress protein adsorption and cell adhesion. (2) For protein immobilization, a PDMAAm (A)-polyAA(PAA) (B) block-graft-copolymerized surface was prepared, where the block B layer covalently fixed the protein and the block A layer functioned as a protective layer to prevent contact of the protein with the substrate. (3) For a drug-releasing surface, a PDMAAm (A)-polyBMA (PBMA) (B) block-graft-copolymerized surface was prepared, where the block A layer contained the drug and the block B layer functioned as a barrier to regulate drug release. These macromolecularly designed surfaces were characterized by X-ray photoelectron spectroscopy, and the immobilization of heparin and protein was visualized by light microscopy, after staining with toluidine blue (for heparin), and fluorescence microscopy (for protein).