Study On Degradation And Release Properties Of PLGA Blend, Gradient And Heparin Contained Films

Percutaneous stent implantation has become the most effective method to deal with vascular stenosis,however,in-stent restenosis remains a challenge after angioplasty and stenting,which restricts the therapy results.Drug-eluting stent(DES) can significantly reduce the rate of in-stent restenosis,and this method becomes the most common method to therapeutic method in percutaneous coronary intervention.Because the drug contained coating contact with blood in human body directly,thus the blood compatibility becomes one of the key factors of the successful application.And it has attracted extensive attention.As a kind of biodegradable materials with good biocompatibility,poly(lactic-co-glycolic acid)(PLGA) was applied as the coatings of coronary stents in this work.And the degradation properties of PLGA blend and gradient films were investigated,furthermore,the modified PLGA which is the block copolymer of PLGA and polyethylene glycol(PEG) was applied to improve the drug-carrying performances.The main contents and results in this paper are shown as follows:1.The in-vitro degradation properties of PLGA blend and gradient films were analyzed and contrasted with single-component films.The results indicated that blend films had balanced degradation property between two original components,and by adjusting the ratio of two components,the degradation property of the blend could be easily controlled.The gradient films were obtained by different ratio of two components in each sublayer,and this non-uniform structure could improve the degradation property of PLGA coating,when PLGA with higher degradation rate such as PLGAS0/50 was decreased gradually from outer to inner part of matrix,stable mass loss curve could be obtained.2.Heparin was mixed with PEG modified PLGA(PLGA-PEG-PLGA),and a small amount of Tween-80 was used as dispersant.The physical,chemical and surface properties of the coating were characterized using Fourier transform infrared spectroscopy(FTIR), scanning electronic microscope(SEM) and contact angle analyzer,in addition,the blood compatibilities were estimated by dynamic cruor time and blood platelet adhesion test.The results revealed that the surface properties of the PLGA-PEG-PLGA/heparin/Tween-80 coating were improved,and the coating had good biocompatibility.