Effects of surface morphology on the biocompatibility of polyhydroxyalkanoates

Abstract

Copolyester consisting of 3-hydroxybutyrate and 3-hydroxyhexanoate (PHBHHx) is a new member of polyhydroxyalkanoate (PHA) family with better mechanical properties and biocompatibility compared with polyhydroxybutyrate (PHB) and polylactic acid (PLA). Mechanical properties of PHB can be improved when PHB is blended with PHBHHx. The effect of surface morphology on the biocompatibility of PHBHHx/PHB blends was investigated. The high crystallization degree and rapid crystallization rate of PHB generate pores and protrusion on the PHB film surface, this coralloid surface could prohibit the attachment and growth of mammalian cells. The presence of PHBHHx in PHB strongly reduced both the crystallization degree and crystallization rate of PHB. The low crystallization degree of PHBHHx/PHB blends provided the blending films with a fairly regular and smooth surface which allowed cell attachment and growth, thus, strongly improved the biocompatibility of PHB. As the PHBHHx content in the blends increased from 0 to 100%, the surface of PHBHHx/PHB blend films transferred from a coralloid surface to a continuous, pore-free one, this change further led to increasing cell number on the PHBHHx/PHB films from 0.13×10 4 to 5.69×10 4 ml −1. Lipase treatment on PHB also transferred the coralloid surface on the PHB film to a regular one, the cells grown on lipase treated PHB film increased 40-folds in number compared with that on the untreated PHB film. For three dimensional porous scaffold, the nutrient and waste transport ability become more important. Thus, the scaffold made from 2:1 PHBHHx/PHB showed a better biocompatibility than that of PHBHHx alone. These results explained the improvement on biocompatibility brought about by PHBHHx, it also demonstrated the feasibility of using blend polymers of PHBHHx/PHB scaffolds as matrix for tissue engineering.