2.1 Materials

Medium-molecular-weight chitosan from shrimp shells (Mw: 645kDa, ≥75%, deacetylated) and medium viscosity (≥2,000 Pa, 2% (25°C; lit.)) alginic acid sodium salt (extracted from brown algae) were purchased from Sigma-Aldrich, United Kingdom. Anhydrous calcium chloride (96.0%) for transforming calcium alginate was obtained from Samchun Pure Chemical Co, Ltd., Korea. BCP powder was synthesized through a microwave assisted hydrothermal process [14, 15] followed by calcination at 900°C for 1hr. High crystallinity is confirmed by XRD.

For the in vitro study, dimethylsulfoxide (99.0%) (DMSO) was purchased from Samchun Pure Chemical Co, Ltd., Korea. Fetal bovine serum (FBS), penicillin-streptomycin antibiotics (PS), 3-[4,5-dimethylthiazol-2-yl] 2,5 diphenyltetrazolium bromide (MTT) solution, and trypsin-EDTA were purchased from Gibco (Carlsbad, CA). Phosphate-buffered saline (PBS) tablets were obtained from Amresco, Korea. MC3T3-E1 mouse pre-osteoblast cells were obtained from the American Type Culture Collection (subclone 4, ATCC, USA). The MC3T3-E1 cells were maintained in a humidified incubator at 37°C and 5% CO₂.New Zealand white rabbits (weight 3kg) were purchased commercially and treated according to the guidelines provided by the Soonchunhyang University.