可降解聚氨酯丙烯酸酯生物材料的制备及其表征

Synthesis and Characterization of Biodegradable Polyurethane-acrylate for Biomaterials

以端羟基聚丙交酯(PLLA)为软段,六亚甲基二异氰酸酯(HDI)和甲基丙烯酸羟乙酯(HEMA)为硬段聚合得到端基为双键的低聚物,再在UV照射下固化得到可生物降解的聚氨酯丙烯酸酯(PUA)生物组织工程材料.PLLA由1,4-丁二醇引发L-丙交酯(L-LA)开环得到.PLLA和低聚物的组成结构用NMR和GPC进行了表征.对固化聚合物PUA的热性能(DSC和TGA)、力学性能(DMA和拉伸)和亲水性(接触角和溶胀)的研究表明增加PLLA软段会增加材料的Tg,但降低材料的亲水性和交联度.PLLA500-HDI的拉伸强度为6.7 MPa,可以满足生物材料的力学性能要求.通过体外降解实验,发现增加PUA材料的软段,降解速率下降.降解16周后,PLLA500-HDI降解最快,失重15.8%,而PLLA2000-HDI的降解速率最慢,失重5.5%,可能与其微相分离的结构有关.红外(ATR)分析表明降解的PUA膜中N—H的伸缩吸收峰(3364 cm-1)变宽和C O吸收峰变尖锐,说明主链中酯键和氨基甲酸酯键都发生了水解.热失重(TGA)曲线上PLLA500-HDI和PLLA1000-HDI降解后的PUA材料热稳定性下降,而PLLA2000-HDI变化不大.此外,在SEM图中发现降解的PLLA500-HDI膜表面出现裂纹和孔洞,PLLA2000-HDI材料表面也形成相分离结构.细胞实验说明材料支持细胞的黏附,有较好的生物相容性,具有应用于组织工程的潜力.

Biodegradable polyurethane-acrylate （PUA） was synthesized via UV-curing of hydroxyl terminated polyurethane acrylate oligomers, which were based on PLLA-diols （PLLA） , 1,6-hexamethylene diisocyanate （HDI） and hydroxyethyl methyl acrylate （HEMA）. PLLA was synthesized by ring opening polymerization of L-lactide （L-LA） initialized by 1,4-butanediol （BDO）. PUA oligomers were characterized by NMR and GPC. Their morphological, hydrophilic and mechanical characteristics were inverstigated using DSC, TGA, DMA, contact angle and swelling analysis. The results showed that, with increasing PLLA length, Tg of PUA increased,while PUA hydrophilicity and erosslink density were reduced. The tensile strength of PLLA500-HDI was 7.6 MPa that met the requirement of the mechanical properties for biomaterials. The degradation experiment indicated that increasing PLLA length lowered PUA degradation rate. The weight loss of PLLA500- HDI was 15.8% ,the highest in the three polymers. PLLA2000-HDI showed the lowest degradation rate,which may be related to its microstructure. ATR analysis showed that the peak at 3364 cm^-1 （N-H） for the degraded film was broadened and the C = O peak （ester and urethane） was sharpened, which indicated the hydrolysis of ester and urethane bonds in the main chain of PUAs. TGA measurement indicated that thermal stability of degraded PLLA500/PLLA1000-HDI was weakened,while PLLA2000-HDI was more stable. SEM of PLLA500-HDI showed crack and holes and the phase separation was observed on the surface of PLLA2000- HDI. Cell culture on PUA materials indicated that they supported the binding of hASCs. Therefore these PUA materials are biocompatible and have potential to be used in hard tissue engineering.