Kana Kobori

Conformational Study of Polypeptide Chains Grafted on the Surface of Polylactide Latex Particle

Polylactide (PLA) latex particle covered with polypeptide chains were prepared by means of solvent exchange method from PLA and PLA-block-polypeptide block copolymer solutions. PLA segment of the block copolymer and PLA homopolymer formed a core of the particle, and the polypeptide segment of the block copolymer, which is designed as tightly fixed biodegradable emulsifier, formed corona around the particle surface. This picture was supported by the fact that zeta-potential of PLA latex particle covered with polypeptide segment was different from that of bare PLA particle because of the presence of the ionizable group in the polypeptide chains. To clarify the effect of the ionizable group on conformation of the polypeptide chain, the relation between the polypeptide chain length and the area occupied by the single block chain was evaluated. The result that the occupied area per a polypeptide chain was linearly increased with the increase in the polypeptide chain length indicates that the polypeptide chains trail on the particle surface and did not take helical structures.