Early Growth of Nano-Sized Calcium Phosphate on Phosphorylated Bacterial Cellulose Nanofibers

It is believed that studies on the early hydroxyapatite (HAp) deposition on nano-sized substrates may possibly allow us to understand the formation mechanisms of biominerals at the molecular level. In this study, bacterial cellulose (BC) nanofibers were phosphorylated and used as nano-sized templates for early mineralization of calcium phosphate (Ca-P). To initiate mineralization the BC nanofibers were immersed in 1.5 times simulated body fluids (1.5 SBF) at 37 °C for varying periods of time. The deposited minerals on the nanofiber surfaces were characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier transformed infrared spectroscopy (FTIR). SEM observations confirmed that early growth (at 4 h) of the Ca-P minerals was heterogeneous, which was followed by extensive spread of the minerals on the entire surfaces of the nanofibers. XRD and FTIR analyses indicated that octacalcium phosphate (OCP) was the precursor of HAp formed on BCnanofibers. Furthermore, HAp deposited on BCnanofibers elongated along the c axis. Nucleation and growth of the Ca-P minerals were analyzed in this paper.