In situ mineralized hydroxyapatite on amino acid modified nanoclays as novel bone biomaterials

A novel biomineralization route to synthesis of hydroxyapatite (HAP) in montmorillonite (MMT) clay galleries modified with 5-aminovaleric acid is presented. The oraganomodified MMT clay with mineralized HAP (in situ HAPclay) was characterized by transmission Fourier Transform infrared (FTIR) spectroscopy to evaluate molecular interactions between clay-modifier-HAP. FTIR spectroscopy studies indicated the formation of HAP within the modified MMT clay galleries. X-ray diffraction (XRD) studies indicated the formation of apatite in modified MMT clay and also showed shifts in peak positions corresponding to the apatite in in situ HAPclay. This indicated that the apatite formed in in situ HAPclay exhibits differences in its lattice structure as compared to ex situ hydroxyapatite (HAP). The in situ HAPclay was further used for the preparation of nanocomposite chitosan/polygalacturonic acid (ChiPgA) composite films. Human osteoblast cells were cultured on these ChiPgA composite films containing in situ HAPclay. Human osteoblasts form clusters and exhibit good biocompatibility with these films. This work demonstrated the potential to design biomineralized HAP in nanocomposites as new bone biomaterials.