Creation of High Performance Biocompatible Surface by Surface modification agent which Constructs High Density Tethered Chains

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We have synthesized seceral types of hydrophilic-hydrophobia block copolymers which forms supramolecular nanostructure in aqueous media due to the self-assembly of the block copolymers. For example, poly(ethylene glycol)/poly(lactide) block copolymer forms spherical core-shell type polymeric micelle in aqueous media, the size of which was 20-40 nm. The shell of the micelle was constructed by tethered PEG chains, whose density was very high in principle because of the thermodynamic balance.The objective of our study was to construct polymer micelle covered surface. If the surface was covered by spherical polymer micelles densely, the density of tethered chains should be much higher that conventional brushed chain surface.We prepared two types of polymer micelle. One of them is poly(2-hydroxyethyl methacrylate)-b-poly(alkylsilylstyrene) (HA) block copolymer micelle. By casting this polymer micelle on the substrate surface, the micelle adsorbed on the surface densely. Platelet adhesion to the modified surface was investigated. The adhesion on the HA-micelle modified surface was mush suppressed than that of not only native substrate but also poly(HEMA) surface. Entropy elastic effect of dense tethered chain may be the reason for this phenomena.Alternately, PEG/PLA block copolymers possessing aldehyde group at PEG chain end and methacryloyl group at PLA chain end was prepared. The block copolymer in aqueous media forms core shell type polymer micelle possessing aldehyde groups on the surface. The methacryloyl group in the core could be polymerized radically to form non dissociative micelle. To a primary-amino containing substrate surface, the aldehyde-micelle was modified covalently via reductive amination reaction. The obtained surface was very dence in polymer micelle and extremely high non-fouling character.These types of highly tethered chain surface was anticipating as new biocompatible surface modification agents.