通过酶催化开环聚合反应合成的高分子量聚酯制成的多孔支架。
Porous scaffolds from high molecular weight polyesters synthesized via enzyme-catalyzed ring-opening polymerization.
作者信息
Srivastava Rajiv K, Albertsson Ann-Christine
机构信息
Department of Fibre and Polymer Technology, School of Chemical Science and Engineering, KTH, Royal Institute of Technology, Stockholm, SE-100 44, Sweden.
出版信息
Biomacromolecules. 2006 Sep;7(9):2531-8. doi: 10.1021/bm060309w.
Several aliphatic polyesters have been synthesized until now using enzyme-catalyzed ring-opening polymerization (ROP) of different lactones, although their molecular weight, hence mechanical strength, was not sufficient enough to fabricate porous scaffolds from them. To achieve this target, 1,5-dioxepan-2-one (DXO) and epsilon-caprolactone (CL) were polymerized in bulk with Lipase CA as catalyst at 60 degrees C, and porous scaffolds were prepared from the polymers obtained thereof using a salt leaching technique. The CL/DXO molar feed ratio was varied from 1.5 to 10, and the reactivity ratios of CL and DXO were determined using the Kelen-Tudos method under such conditions of polymerization. NMR results showed a slightly lower CL/DXO molar ratio in the copolymers than in the feed due to high reactivity of DXO toward Lipase CA catalysis. The crystallinity of the PCL segment of the copolymers was affected by the presence of soft and amorphous DXO domains. The copolymers having high CL content were thermally more stable. The porosity of the scaffolds was in the range 82-88%, and the SEM analysis showed interconnected pores in the scaffolds. Of the two parameters which could affect the mechanical properties, viz., the copolymer composition and the scaffold pore size, the pore size showed a significant effect on the mechanical properties of the scaffolds. The porous scaffolds developed in this way for tissue engineering are free from toxic organometallic catalyst residues, and they are highly suitable for biomedical applications.
迄今为止,人们已经通过酶催化不同内酯的开环聚合反应(ROP)合成了几种脂肪族聚酯,尽管它们的分子量以及由此而来的机械强度还不足以用其制造多孔支架。为了实现这一目标,以脂肪酶CA作为催化剂,在60℃下使1,5-二氧杂环庚烷-2-酮(DXO)和ε-己内酯(CL)进行本体聚合反应,然后使用盐析技术从所得聚合物制备多孔支架。CL/DXO的摩尔进料比在1.5至10之间变化,并在这种聚合条件下使用凯伦-图多斯方法测定CL和DXO的竞聚率。核磁共振结果表明,由于DXO对脂肪酶CA催化反应的高反应活性,共聚物中的CL/DXO摩尔比略低于进料中的摩尔比。共聚物中聚己内酯链段的结晶度受到柔软且无定形的DXO链段的影响。具有高CL含量的共聚物在热稳定性上更高。支架的孔隙率在82%至88%的范围内,扫描电子显微镜分析表明支架中存在相互连通的孔隙。在可能影响机械性能的两个参数中,即共聚物组成和支架孔径,孔径对支架的机械性能有显著影响。以这种方式开发的用于组织工程的多孔支架不含有毒有机金属催化剂残留,并且非常适合生物医学应用。