Study On The Preparation And Degradation Of Poly (Lactic Acid)-Poly (Ethylene Glycol)-Poly (Lactic Acid)/SiO₂ Hybrid Material

The synthesis and characterization of poly(lactic acid)-poly(ethylene glycol)-poly(lactic acid)(PLA-PEG-PLA)/SiO₂ hybrid material was explored in this paper.Using tetraethoxysilane(TEOS)and PLA-PEG-PLA as start material, PLA-PEG-PLA/SiO₂ hybrid material was synthesized by sol-gel method,and the relative result products were characterized by FT-IR,XPS,DSC,XRD and SEM.The results indicated that SiO₂ combined with PLA-PEG-PLA by C-O-Si bond.Compare with pure PLA-PEG-PLA material, PLA-PEG-PLA/SiO₂ hybrid material was amorphous alike pure PLA-PEG-PLA,but the glass transition temperature of PLA-PEG-PLA/SiO₂ hybrid material is higher than that of PLA-PEG-PLA and increases with increase of silica content.The in vitro degradation of hybrid materials was conducted in normal saline at 37℃.The results showed that after the PLA-PEG-PLA/SiO₂ hybrid material degraded in saline for 12 weeks,a three-dimensional porous scaffold was obtained.This character scaffold is available for the growth of cells and blood vessel.Moreover,the hydroxyl groups on SiO₂ of the PLA-PEG-PLA/SiO₂ hybrid material could buffer the acidic degrading products of PLA chain,which could decrease the inflammatory and was beneficial to proliferation of cell,tissue repairing.Using PLA-PEG-PLA/SiO₂ hybrid material as drug carrier, dexamethasone sodium phosphate(DSP)-PLA-PEG-PLA/SiO₂ microspheres were prepared by water-in-oil-in-water(W/O/W)emulsion solvent evaporation method,and the particle size,drug loading and in vitro release of the microsphere was investigated.The microspheres are sized about 8μm in diameter and drug loading is about 5.72%,which may be used in controlled-release of drug.The in vitro release results indicated that DSP-PLA-PEG-PLA/SiO₂ microspheres had an obvious sustained release effect.