Paper Title
Preparation and Characterization of Alginate - Hydroxyapatite Paste for Bone Regeneration

The objective of the present study was to prepare Si doped hydroxyapatite nanopowder incorporated photocurable aligate paste suitable for orthopaedic application. 0.4 wt% silicon substituted hydroxyapatite nanopowder with average particle size between 85- 90 nm was synthesized using wet chemical method. X- ray diffraction and FTIR analysis confirmed substitution of PO4 3– with SiO4 4- groups in prepared HAp nanopowder. On addition of Si into hydroxyapatite lattice, crystallite size of the prepared nanopowder was decreased from 14 nm to 11 nm. XRD results further revealed that alginate became predominantly amorphous with successful methacrylation using methacrylic anhydride. Methacrylatemodified alginate, showed new peaks at 1.8–2.0, 5.7–5.9, 6.1–6.3 ppm due to the presence of methacrylate proton as suggested by NMR studies which further confirmed successful methacrylation of alginate. Methacrylated alginate and Si doped HAp nanopowders were mixed in a weight ratio of 4:1 to prepare a phtocroslinkable paste in presence of 0.5% wt/v photoinitiator such as irgacure. The prepared paste showed good injectability and hardenability on exposure of ~365 nm UV radiation for 10 minutes to give a biopolymer matrix with little open porosity.