ABSTRACT
BACKGROUND:Calcium citrate has a better solubility than calcium phosphate, calcium sulfate, and other calcium biomaterials. The synthetic calcium citrate has a good denseness, and stably releases calcium ions at a high efficiency during the degradation. Consequently, it may be more suitable for the fil ing of fracture defects, providing needed calcium ions for early fracture healing. OBJECTIVE:To prepare calcium citrate biomaterials with a novel formulation based on the natural bio-mineralized oyster shel s and citric acid so as to expect to get a good application in fracture healing repair. METHODS:Crushing, grinding, and chemical reaction methods were used for refinement. Particle size analyzer, X-ray diffraction, scanning electron microscope, and Fourier transform infrared spectroscopy were adopted for analysis of the size distribution, composition, mineral phases, and micro-morphology. Biological characteristics were evaluated through a simulated body fluid experiment. RESULTS AND CONCLUSION:Oyster shel powder was reacted with saturated citric acid to produce the calcium citrate material that had uniform crystal structure and compact bonding among crystal bodies, and exhibited a certain mechanical ability. The calcium citrate material had a good crystal structure that was conductive to prolong the degradation time. The calcium citrate released calcium ions slowly, and did not produce dramatic changes in the pH value (7.20-7.46) of the surrounding in the dissolution process. With the gradual degradation of calcium citrate materials, Ca2+concentration in solution increased gradual y and stably, and ultimately achieved an appropriate concentration of 7 mmol/L, suitable for osteoblast proliferation and differentiation. Calcium citrate prepared using natural oyster shel has good biological properties, and exhibits a natural superiority to artificial bone materials.