Preparation Of NHAP/PLA Hollow Porous Microspheres And Osteoblasts Response

Bone tissue engineering is recognized as one of the most promising methods of treatment for repairing bone defects. The bioreactor is an important way to get a lot of the bone tissue seed cells. Microspheres are of a large specific surface area, so that cells can proliferate on the surface of the microspheres in a short time and a large number of cells can be obtained. And the training process can be completed by adding new microcarriers, to avoid the damage of trypsin digestion in traditional culture. But the current commercial microcarriers are of poor degradation, expensive price and other shortcomings. Therefore, the development of high-quality microcarriers material is still current research focus. Porogen united emulsion evaporation method is used to prepare the PLA and nHAP/PLA porous hollow microspheres. The chemical and physical properties of the different microspheres are studied. Osteoblasts are seeded on microspheres to investigate the biocompatibility of microspheres. So the microspheres that are suitable to the growth of the osteoblasts are prepared.The CH2Cl2 is the solvent. Gelatin is a dispersing agent. NH4HCO3 is the porogen. The hollow porous PLA microspheres are prepared. Their particle size and size distribution could be controlled by stirring rate, PLA concentration and dispersant concentration. In the same way, nHAP/PLA microspheres are prepared. The microspheres of different nHAP amount have different surface topography, water absorption, contact angle and suspending ability. By comparing these, the microspheres that are most suitable for cell culture are selected. And the preparation process is optimized by orthogonal experiment. The 4th Osteoblasts （OBs） are seeded onto microspheres to study the adhesion, proliferation and protein expression of OBs.Experimental results show that particle size increases with increasing concentration of PLA, decreases with the increasing concentration of dispersant and the reduced stirring speed. The particle size of nHAP/PLA microspheres decreases and then increases with increasing concentration of nHAP. The orthogonal experiment results show that the optimum level combination is 10% PLA,0.25% gelatin,300 rpm and 10% NH4HCO3. The 20%-nHAP/PLA microspheres have the maximum protein adsorption capacity, hydrophilicity and cell adhesion ability. OBs on 20%-nHAP/PLA microspheres is the most and evenly distributed after cultured 5 d, and have the highest content of ALP and total protein after cultured 14 d and 21 d.Through the above experimental results, we can draw that prepared by porogen united emulsion evaporation method,20%-nHAP/PLA microspheres whose contact angle is 70 o have high hydrophobicity, cell adhesion and protein adsorption capacity proliferation. So 20%-nHAP/PLA microspheres are the most suitable for the growth of OBs. The best preparation Process is 10% PLA,0.25% gelatin,300 rpm and 10% NH₄HCO₃.