Fabrication of asymmetric membranes from polyhydroxybutyrate and biphasic calcium phosphate/chitosan for guided bone regeneration

Chitosan (CS) is known for its biocompatibility, antibacterial function, and wound healing acceleration, while calcium phosphate (CP) can promote bone regeneration. However, to be useful as barrier membrane for guided bone regeneration (GBR) in periodontal treatments, the membranes must have suitable mechanical strength in addition to good barrier properties. Therefore, a dense polyhydroxybutyrate (PHB) layer was integrated with a porous biphasic calcium phosphate/chitosan (BCP/CS) layer to form an asymmetric PHB-BCP/CS membrane. Moreover, for enhancing the interfacial strength, the PHB layer was chemically bonded to the BCP/CS layer through plasma-induced grafting of poly(acrylic acid) on its surface and followed by amidation with CS via carbodiimide activation. The incorporation of the PHB layer greatly increased the initial modulus and ultimate tensile strength of the membrane up to 524 and 16.5 MPa, respectively. In addition, the human gingival fibroblast (HGF) cells could proliferate very well on the PHB layer of the membrane, yet they were prohibited from down-growing through the membrane. Also, the addition of BCP particles in the CS layer increased the proliferation of osteoblast cells. Thus, the asymmetric PHB-BCP/CS membrane has the potential to be used as a barrier membrane for GBR in periodontal tissue engineering.