Department of Pharmaceutics, College of Chemical Engineering, Qingdao University of Science and Technology, 53 Zhengzhou Road, Qingdao 266042, China.
Department of Pharmaceutics, College of Chemical Engineering, Qingdao University of Science and Technology, 53 Zhengzhou Road, Qingdao 266042, China.
J Biotechnol. 2018 Sep 10;281:74-80. doi: 10.1016/j.jbiotec.2018.06.338. Epub 2018 Jun 21.
A novel method to synthesize poly(ε-caprolactone) (PCL) through a three-step, lipase-mediated chemo-enzymatic reaction from cyclohexanone using an immobilized lipase from Trichosporon laibacchii (T. laibacchii) CBS5791 was developed. The immobilized preparation with 1280 U· g used here was obtained by a method of purification and in situ immobilization where the crude intracellular lipase (cell homogenate) was subjected to partial purification by an aqueous two-phase system (ATPS) consisting of 12% (w/w) polyethylene glycol (PEG) 4000 and 13% (w/w) potassium phosphate (KHPO) and then in situ immobilization directly on diatomite from the top PEG-rich phase of ATPS. In this multi-step process, the ε-caprolactone (ε-CL) produced by lipase-mediated one-pot two-step chemo-enzymatic oxidation of cyclohexanone was directly subjected to in situ ring-opening polymerization (ROP) started by adding highly hydrophobic solvents. It is necessary to note that ε-CL synthesis and its subsequent ROP were catalyzed by the same lipase. The impact of various reaction parameters, e.g., solvent, cyclohexanone: hydrogen peroxide molar ratio, hydrogen peroxide forms and reaction temperature were investigated. Toluene was selected as a preferred solvent due to supporting the highest molecular weight (M = 2168) and moderate ε-CL conversion (65.42%). Through the optimization of reaction conditions, PCL was produced with a M of 2283 at 50 °C for 24 h. These results reveal that this lipase-mediated direct ring-opening polymerization of in situ formed ε-CL is an alternative route to the conventional synthesis of PCL.
一种通过三步酶促化学方法从环己酮合成聚己内酯（PCL）的新方法，使用固定化脂肪酶从 Trichosporon laibacchii（T. laibacchii）CBS5791 进行。这里使用的固定化制剂是通过纯化和原位固定化方法获得的，其中粗细胞内脂肪酶（细胞匀浆）通过由 12%（w/w）聚乙二醇（PEG）4000 和 13%（w/w）磷酸钾（KHPO）组成的双水相系统（ATPS）进行部分纯化，然后直接原位固定在 ATPS 的顶部 PEG 富相上的硅藻土上。在这个多步过程中，通过脂肪酶介导的一锅两步化学酶促氧化环己酮直接进行原位开环聚合（ROP），在添加高疏水性溶剂后引发。需要注意的是，ε-CL 的合成及其随后的 ROP 均由同一种脂肪酶催化。研究了各种反应参数的影响，例如溶剂、环己酮：过氧化氢摩尔比、过氧化氢形式和反应温度。甲苯被选为首选溶剂，因为它支持最高的分子量（M=2168）和适度的 ε-CL 转化率（65.42%）。通过优化反应条件，在 50°C 下反应 24 小时，可得到分子量为 2283 的 PCL。这些结果表明，这种脂肪酶介导的原位形成的 ε-CL 的直接开环聚合是传统 PCL 合成的替代途径。
