Difference in the attachment of hepatocytes between a poly(γ-benzyl L-glutamate) (PBLG)/poly(N-isopropylacrylamide) (PNIPAAm) diblock copolymer cast surface and a PBLG/PNIPAAm Langmuir-Blodgett one

The effects of temperature on the monolayer behavior of the poly(y-benzyl L-glutamate) (PBLG)/poly(N-isopropylacrylamide,) (PNIPAAm) diblock copolymer at the air-water interface were examined. Differences in the adhesion and morphology of hepatocytes between Langmuir-Blodgett (LB) films and cast surfaces of the PBLG/PNIPAAm diblock copolymer were investigated. The surface pressure (pi)-area (A) curve of the block copolymer had a tendency to expand with the temperature, due to a change in the conformation of PNIPAAm with the temperature change. Attachment of hepatocytes onto the PBLG/PNIPAAm block copolymer LB surface decreased slightly with an increase of the PNIPAAm content in the block copolymer, whereas that onto the cast surface decreased rapidly with an increase of the PNIPAAm content, due to the hydrophilic property of PNIPAAm in the microphase-separated structure. Rapid morphological changes of the hepatocytes adhered to the LB surfaces, from round shapes to spreading ones, were observed, compared with the cast films. The hepatocytes that adhered to the block copolymer LB surfaces showed less flattened and spread shapes than those that adhered to the PBLG one. Also, the spheroid formation of the hepatocytes increased with an increase of the PNIPAAm content in the block copolymer cast films.