Preparation Of PLA Nanoparticles And Protein Adsorption Performance

Poly (lactic acid) nanoparticles were prepared by desolvation method. Several key factors on particle size including PLA concentration, rate of organic solution and water, mixing speed, molecular weight of PLA and temperature were discussed in the article to find a suitable condition to prepare particles of suitable size and shape. Morphology of these particles was analyzed using transmission electron microscopy (TEM) and dynamic light scattering technology (DLS). The best condition was polymer concentration5mg/ml, oil water ratio25:15, mixing speed1000r/min, polymer molecular weight50kDa and distillation temperature25℃, and the size of nanoparticles prepared in optimal conditions were164.5±11.5nm, the PDI was0.018±0.012and the zeta potential-27.4±2.1mV, which meant the particles could keep stable in soultion.Some of the pharmaceutical properties of nanoparticles were discussed, such as polymer degradation properties, storage stability of nanoparticles and the freeze-drying process. The result of storage indicated that no changes in the size and PDI happened after storing under4℃for3months, while the degradation experiment revealed that nanoparticles prepared by polymer with molecular weight lOkDa,30kDa and50kDa degraded in different levels. The small molecular weight was the serious degradation appeared. Among the three kinds of freeze drying protective agent, glucose, sucrose and mannitol, sucrose showed the best protection of nanoparticles from aggregation. Adding glucose of5%concentration could help nanoparticles keep their small sizes and good dispersion after freeze-drying process.The loading capacity of BSA (bovine serum albumin) and lysozyme was evaluated as a function of protein concentration, pH, ionic strength and time. The effect of temperature was also concerned. The result showed the max adsorption capacity of BSA was30.1mg/g under the conditions of pH6.0, protein concentration200μg/mL and temperature25℃, with no change on size and PDI of nanoparticles. The max adsorption capacity of Lysozyme was40.7mg/g under the conditions of pH8.0, protein concentration250μg/mL and temperature25℃, more than BSA, but adhesion occurs on the surface due to strong electrostatic interaction between protein and nanoparticles. The results of SDS-PAGE showed that preparation conditions did not cause any degradation on the proteins. The in vitro release rate of BSA from PLA nanoparticles was initially rapid, with about20%release in24h at37℃Subsequently, the rate of release was slow and by day10about50%of the adsorbed protein could be detected in the release medium.The loading capacity of HBsAg was also analyzed. It appeared that the adsorption rate of HBsAg changed little as pH changed, while it raised as concentration of NaCl increased. The max adsorption capacity of HBsAg was10.2mg/g under the concentration of NaCl9g/L.