Plate-shape carbonated hydroxyapatite/collagen nanocomposite hydrogel via in situ mineralization of hydroxyapatite concurrent with gelation of collagen at pH = 7.4 and 37°C.

The objective of this study was to develop a collagen/hydroxyapatite (HA) nanocomposite scaffold for bone tissue engineering applications. For this purpose, in situ mineralization of HA was accompanied with formation of collagen hydrogel at condition similar to the physiological condition, pH = 7.4, and 37°C. The physicochemical and biological properties of the in situ scaffold were compared with nanocomposite fabricated by mixing HA powder and collagen hydrogel (powder-mixed scaffold). The HA in this method was formed in the same condition as the in situ method. X-ray diffraction and FTIR analysis of in situ scaffold showed the formation of carbonated HA, similar to bone, while the HA powder in powder-mixed scaffold showed non-carbonated structure. Scanning electron microscopy revealed the formation of fibrillated collagen in both composites. HA was observed in both scaffolds, but with different morphology. The in situ formed HA had a plate-like morphology while the preformed HA showed spherical morphology in the powder-mixed scaffold. The in-vitro cytocompatibility and osteogenesis activity of scaffolds using osteoblast-like cells (MG-63) showed higher cytocompatibility and more osteogenesis capability of the in situ scaffold in comparison with the powder-mixed scaffold. The results suggest the in situ method as a proper approach for fabrication of HA/collagen scaffolds with similar properties like bone. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 1920-1929, 2019.