[Study on the in vitro release behavior of bovine serum albumin from calcium phosphate coating on pure titanium surface].

Objective: To study the incorporation rate and release behavior of bovine serum albumin (BSA) incorporated into the calcium phosphate coating by biomimetic deposition, as well as the physical and chemical properties of the hybrid coating, and to provide experimental basis for the fabrication of growth factor/biomimetic calcium phosphate coating and exploration for the loading/release behavior of growth factors.

Methods: Pure titanium specimens were immersed into saturated calcium phosphate solutions(SCP) containing no BSA (controlled group) and 3 different concentrations of BSA (experimental groups) : 1, 10 and 100 mg/L. Biomimetic calcium phosphate coating was formed on titanium surface and BSA was incorporated into the coating through co-deposition. The topography of the specimen was observed using scanning electron microscopy (SEM). Chemical structure and phase composition of coatings were detected by Fourier infrared spectroscopy (FTIR) analysis and X-ray diffraction (XRD) respectively. BSA incorporation rate and release profile were determined by bicinchoninic acid protein assay kit.

Results: The biomimetic calcium phosphate coating was mainly composed of hydroxyapatite and octacalcium phosphate. BSA was successfully incorporated into the calcium phosphate coatings in all the 3 experimental groups. With the increase of BSA concentration, plate-like units of the coatings were turned into small grid structure. BSA incorporation rates of the three experimental groups were (72.4 ± 2.4)%, (62.3 ± 0.9)% and (42.2 ± 1.7)% respectively. The in vitro release test showed that all three BSA release profiles could be divided into two significant different stages: early burst release stage and later sustained release stage. The amount of BSA release of the 3 experimental groups in 24 h and 30 d were (1.57 ± 0.09), (8.82 ± 0.93), (140.24 ± 3.12) µg, and (2.39 ± 0.29), (14.39 ± 0.70), (151.06 ± 2.00) µg respectively.

Conclusions: Biomimetic calcium phosphate coating can be used as an effective carrier for protein. BSA concentration has an impact on the incorporation rate and release speed of BSA from the calcium phosphate coating. Favorable BSA incorporation rate and release behavior can be obtained at BSA concentration of 10 mg/L.