Effect Of Radiation Sterilization And Nanocapsulation On The Activity Of Bone Morphogenetic Proteins

Bone morphogenetic proteins(BMPs) have been extensively used to functionalize the medical implant to promote the bone repairing. However, the deactivation of BMP during the processing hinders the clinical application and has become a bottleneck of industrialization. We herein investigated the BMP activity under the irradiation sterilization, and at the same time, we also studied the effect of nanocapsulation of BMP on their activity in the polyactic acid membrane.First,BMP was sterilized by gamma ray and their osteoinduction activity was compared with that before sterilization. The structure of BMP was analyzed by gel electrophoresis and matrix-assisted laser desorption-tandem time of flight mass spectrometry(MALDI-TOF MS). The results show that BMP proteins were degraded by radiation, leading to the decrease of their osteogenic activity in vivo, however, their in vitro osteoinduction activity was slightly increased.Next, nanocapsules entrapped BMP were synthesized through single-protein nanocapsules technology. The average diameter of BMP nanocapsules was about 20 nm. The nanocapsules were treated with acetone, ethyl acetate, chloroform and methylene chloride, and the BMP activity was investigated by cell experiments. The results showed that nanocapsulation increased the stability of BMP in the organic solvents. Based on these results, BMP nanocapsules/polylactic acid composite membrane was prepared by using methylene chloride as solvent. The results of cell experiments indicated that the loss of activity of BMP less than 10%, much less than than of BMP embedded in polylactic acid directly, demonstrating the capability of nanocapsulation preserved the osteoinductive potential of BMP.