Biomimetic synthesis of nanocrystalline hydroxyapatite from sharkskin collagen

Hydroxyapatite (HA) ceramics have gained popularity as bone-grafting materials due to their excellent biocompatibility. However, chemically synthesized HA lacks a strong load-bearing capacity as required by bones. An alternative solution is to grow HA crystals by biomimetic mineralization of collagen under laboratory conditions. Marine industry wastes such as skin and bones, generally dumped in landfill, provide an alternative cheap source of collagen. This study was undertaken to utilize the recovered collagen from sharkskin, generally discarded as waste, as a substrate for growing nanocrystalline HA. Hammerhead sharkskin collagen was isolated, characterized and identified as type I. The biomimetic growth of HA was induced by subjecting the purified collagen to optimal mineralization condition with an in vitro nucleation solution. Fourier transform infrared spectroscopy and X-ray diffraction studies revealed the formation of HA after 21 d of incubation. The dimensions of the crystals were determined to be in the nanoscale range by scanning electron microscopy and atomic force microscopy. Osteoblasts displayed significantly higher adhesion and differentiation compared to Vero cells on dishes coated with HA crystals. The size, crystallinity and cellular interaction of biomimetically grown HA indicated that sharkskin could offer an ideal alternative substrate for nucleating bone growth in vivo.