Osteogenesis and Degradability of Bioresorbable Biphasic Gypsum-Carbonated Apatite Granules for Bone Tissue Engineering

Osteogenesis and degradability of bioresorbable biphasic gypsum-carbonated apatite granules (BPG) were investigated. Three different sizes of gypsum, 300-600 μm (small), 600-1000 μm (medium) and 1000-2000 μm (large), denoted as S, M and L respectively, were developed through the crushing and sieving method. Exposure of gypsum granules in carbonate and phosphate sources formed BPG through dissolution and precipitation mechanism. BPG was firstly examined by X-ray Diffractometer (XRD) and Fourier Transform Infrared Spectrometer (FTIR) to confirm its phase and chemical composition respectively. In-vitro cell proliferation, alkaline phosphatase (ALP) activity and adhesion of human osteoblast (hFOB) were investigated for osteogenesis evaluation. Degradability in phosphate buffer saline (PBS) was characterized by weight loss whereas apatite mineralization on the BPG surface was examined using Scanning Electron Microscope (SEM). BPG with 300-600 μm and 600-1000 μm enhanced osteogenic differentiation of hFOB and accelerated differentiation process better than 1000-2000 μm as indicated by cell proliferation and ALP activity. Good hFOB adhesion was observed on all BPG surfaces. The weight loss of L and M was 68% and 59%, respectively, which are higher than S at only 32%, indicating faster degradation of large BPG compared to smaller granules upon immersion for 35 days. This in turn, suggested the ionic dissolution of BPG which has contributed to the apatite formation on its surface. The results suggest, the BPG mimicked the bone matrix, exhibited good osteogenesis and degradability, which might be used as a potential candidate for bone tissue engineering.