Biodegradable Synthesis, Characterization And Biological Evaluation Of The Fat / Aromatic Polyether Ester Elastomer

Recently, biodegradable aliphatic/aromatic poly(ether ester) elstomers have gained increasing interest of biomaterial researchers for their favorable biocompatibility, adjustable mechanics and degradation properties. This article is mainly focused on the synthesis, scaffold preparation, biocompatibility evaluation, sterilization and cell/scaffold confluent culture of four series biodegradable aliphatic/aromatic poly(ether ester) elstomers.For the first time, based on 1, 4-cyclohexane dicarboxylic acid(CHDA), dimethyl terephthalate (DMT), 1, 4-butanediol(BDO) and poly(ethylene glycol)(PEG), a series of biodegradable aliphatic/aromatic poly(ether ester) elastomers ---- poly(butylene terephthalate)-co-poly(butylene cyclohexanedicarboxylate) -b- poly(ethylene glycol) (PTCG) were prepared by a two-step melt polycondensation method. The effects of aliphatic ester content on the physical, mechanical and thermal properties, as well as in vitro and in vivo degradation behaviors were investigated. The characterization results suggested that: PTCG copolymers are microphase separated in microstructure, they are composed by crystalline hard segments, amorphous hard and soft segments; part cis-CHDA units isomerized to trans units in the synthesis process; the macroscopical properties of PTCG copolymers are depended on CHDA molar content: the decrease in mechanical strength and faster degradation rates were observed with the increasing poly(butylene cyclo-hexanedicarboxylate) (PBC) molar fraction; the surface structures of PTCG copolymers fit well with Seymour's model, that is, soft phase is embedded between radial crystalline fibrils of spherulites consisting of the hard segments.Three kinds of technologies were adopted to prepare porous scaffold. First, two modified solvent cast/particle leaching methods were employed, thus the porogen aggradation was prevented, and porous 3-D scaffold were obtained. Second, phase-separation/freeze drying technique was exploited as our preferred method, the results indicated that 1): when liquid-solid phase-separation/freeze drying method was used, the scaffold aperture is above 100μm if the pretreatment temperature is settled at 0℃; 2): when liquid-liquid phase-separation/freeze drying method was used, highly opening porous scaffold could be obtained if the dioxane:water ratio is 85:15 and pretreatment temperature is settled at -18℃. Third, electrospinning results suggested that the electrospun process of PBCT solution keeps to the theory put forward by Shin. When the solution concerntration is 20%, the voltage is 15kV; the liquid jet is in instability region.According to National Standard GB/T16886.5 and 16886.6, biocompatibility evaluation of four series of biodegradable aliphatic/aromatic poly(ether ester) elastomers----poly(buylene terephthalate)/poly(ethylene glycol terephthalate) (PTGT /PBT), poly(buylene terephthalate)-co-poly(butylene succinate)-b-poly(ethylene glycol) (PTSG), poly(buylene terephthalate)-co-poly(cyclohexane terephthalate) -b-poly(ethylene glycol) (PBCT) and PTCG, were carried out. The results showed that the all poly(ether ester) elastomers posses good biocompatibility, and their cytotoxicity are less than grade 1.The poly(ether ester) elastomers were surface modified by using NH3 and SO2 gas plasma treatment. Results suggested that NH3 gas plasma treatment can markedly improve cell adhesion and proliferation ability on poly(ether ester) films. SO2 gas plasma treatment only works well in the modification of PEGT/PBT and PTSG films, but does not affect PBCT surface property effectively.The effects on the poly(ether ester) elastomer properties of different sterilization method were studied in detail.γ-irradiation and ethylene oxide sterilization led to the degradation of poly(ether ester) elastomer, while high-pressure steam sterilization enhanced the hydrophilicity of poly(ether ester) elastomer surface, thus restrained cell adhesion and proliferation on poly(ether ester) films. So they are unsuitable for poly(ether ester) elastomer sterilization. Seed cells grew well on high-pressure steam/ ultraviolet radiation and high-pressure steam/70% ethanol sterilized films, which indicated that above method, are suitable for poly(ether ester) elastomer sterilization.Canine smooth muscle cells and marrow cells were chose as seed cells to be cultured on poly(ether ester) scaffolds. Static culture results showed that smooth cell grew well on the scaffolds, while the dynamic culture results are not satisfactory. It is need to optimize the seeding method and dynamic culture condition.