Nanocomposite of cosubstituted carbonated hydroxyapatite fabricated inside Poly(sodium hyaluronate-acrylamide) hydrogel template prepared by gamma radiation for osteoblast cell regeneration

Abstract

Carbonated hydroxyapatite (CCaHAp) closely mimics the chemical composition of apatite found in human bone, compared to hydroxyapatite (HA). The present study aimed to prepare CCaHAp nanocomposite using a copolymer of sodium hyaluronate-polyacrylamide (poly(Hya-AAm)) hydrogel as a HA template. Here, a gamma irradiation technique was utilized for preparing poly(Hya-AAm) hydrogel. The hydrogel had a dual function as a HA template and carbon precursor. The CCaHAp nanocomposite was synthesized in situ by impregnating swollen discs of poly(Hya-AAm) hydrogel in the dual solution of phosphoric acid and calcium nitrate. The impregnation cycle was repeated one, two, three, and four times to fabricate four samples of CCaHAp with Ca/P ratios of 1.67, 1.89, 1.48, and 1.37 and carbon content of 8.6, 12.25, 12.24, and 10.07%, respectively, with minor cosubstitution of Na and Mg atoms. Moreover, this study analyzed the effectiveness of CCaHAp compared with HA, which was used as a control for in vitro osteoblast cell regeneration. Four CCaHAp and HA discs were seeded with the MC3T3-E1 osteoblast cells. On day 1, increased cell attachment was observed in the four samples of CCaHAp compared with that in HA discs. Furthermore, compared with the HA control, cell differentiation and regeneration were significantly increased in the CCaHAp samples on day 21, especially in the CCaHAp sample with a Ca/P ratio of 1.89. This study found that the use of CCaHAp as a nanobiocompatible material potentially improved osteogenic ability compared with HA.