Characteristic cell adhesion behaviors on various derivatives of poly(3-hydroxybutyrate) (PHB) and a block copolymer of poly(3-[RS]-hydroxybutyrate) and poly(oxyethylene)

A high-molecular-weight ABA tri-block copolymer ([RS]-PHB/PEG), consisting of poly(3-[RS]-hydroxybutyrate) ([RS]-PHB: A) and poly(oxyethylene) (polyethylene glycol; PEG: B), was synthesized by ring-opening polymerization of [RS]-β-butyrolactone ([RS]-βBL) in the presence of PEG and 1,3-dichlorotetrabutyldistannoxane (DTD) as the catalyst. By using a series of PHB derivatives including the new block copolymer, cell adhesion was evaluated with 3T3 fibroblast cells. It was found out that the attached cells didn't extend on [RS]-PHB, but extended on [R]-PHB although the numbers of the attached cells were very small on both [RS]-PHB and [R]-PHB. [RS]-PHB/PEG exhibited even poorer cell adhesion than [RS]-PHB because of the increased hydrophilic nature due to the PEG segments. Although the amount of fibronectin adsorbed on the surface of [RS]-PHB was higher than that on the surface of [R]-PHB, the cell adhesion became poorer on the fibronectin-pre-adsorbed [RS]-PHB. These differences in cell adhesion among these PHB derivatives were reasonably attributed to their surface properties related with the accumulation of methyl groups.