The addition of poly(ethylene glycol), PEG, to bioprocessing systems producing polyhydroxyalkanoates (PHAs), has been reported as a means of their molecular weight control and can also support bioPEGylation, resulting in hybrids with amphiphillic properties. However, the study of such natural-synthetic hybrids of PHA-b-PEG is still in its infancy. In this study, we report the influence of bioPEGylation of polyhydroxyoctanoate (PHO) on its physiochemical, material, and biological properties. Consistent with previous studies, bioPEGylation with diethylene glycol (DEG) showed a significant reduction in PHA molecular weight (57%). In comparison to solvent cast films of PHO, PHO-b-DEG films possessed a noticeable X-ray diffraction peak at 9.82 degrees and increased Young's modulus of 11 Gpa (83%). Potential biocompatibility was investigated by measuring the early phase of apoptosis in myoblastic satellite-stem cells (C2C12). Comparative analysis of cell proliferation and progression in the presence of the mcl-PHA and its hybrid showed that the latter induced significant cell cycle progression: the first time a biomaterial has been shown to do so. Microtopographies of the film surfaces demonstrated that these differences were not due to changes in surface morphology; both polymers possessed average surface rugosities of 1.4 +/- 0.2 mu m. However, a slight decrease in surface hydrophobicity (3.5 +/- 0.9 degrees) due to the hydrophilic DEG may have exerted an influence. The results support the further study of bioPEGylated PHAs as potential biomaterials in the field of tissue engineering.