This study implements a convenient microreactor for biocatalysis with enzymes immobilized on magnetic nanoparticles (MNPs). The enzyme immobilized onto MNPs by adsorption or by covalent bonds was lipase B from Candida antarctica (CaLB). The MNPs for adsorption were obtained by covering the magnetite core with a silica shell and later with hexadecyltrimethoxysilane, while for covalent immobilization, the silica-covered MNPs were functionalized by a layer forming from mixtures of hexadecyl- and 3-(2-aminoethylamino)propyldimethoxymethylsilanes in 16:1 molar ratio, which was further activated with neopentyl glycol diglycidyl ether (NGDE). The resulting CaLB-MNPs were tested in a convenient continuous flow system, created by 3D printing to hold six adjustable permanent magnets beneath a polytetrafluoroethylene tube (PTFE) to anchor the MNP biocatalyst inside the tube reactor. The anchored CaLB-MNPs formed reaction chambers in the tube for passing the fluid through and above the MNP biocatalysts, thus increasing the mixing during the fluid flow and resulting in enhanced activity of CaLB on MNPs. The enantiomer selective acylation of 4-(morpholin-4-yl)butan-2-ol (±)-1, being the chiral alcohol constituent of the mucolytic drug Fedrilate, was carried out by CaLB-MNPs in the U-shape reactor. The CaLB-MNPs in the U-shape reactor were compared in batch reactions to the lyophilized CaLB and to the CaLB-MNPs using the same reaction composition, and the same amounts of CaLB showed similar or higher activity in flow mode and superior activity as compared to the lyophilized powder form. The U-shape permanent magnet design represents a general and easy-to-access implementation of MNP-based flow microreactors, being useful for many biotransformations and reducing costly and time-consuming downstream processes.

中文翻译：

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一种方便的 U 型微反应器，用于酶包覆磁性纳米颗粒的连续流动生物催化——脂肪酶催化的 4-(吗啉-4-基)丁-2-醇的对映异构体选择性酰化

本研究实现了一种方便的微反应器，用于生物催化，其中酶固定在磁性纳米粒子 (MNP) 上。通过吸附或共价键固定在 MNPs 上的酶是来自南极念珠菌的脂肪酶 B(CaLB)。用于吸附的 MNPs 是通过用二氧化硅壳覆盖磁铁矿核，然后用十六烷基三甲氧基硅烷覆盖，而对于共价固定，二氧化硅覆盖的 MNPs 通过由十六烷基和 3-(2-氨基乙基氨基)丙基二甲氧基甲基硅烷的混合物形成的层功能化以 16:1 的摩尔比，用新戊二醇二缩水甘油醚 (NGDE) 进一步活化。生成的 CaLB-MNP 在方便的连续流动系统中进行了测试，该系统由 3D 打印创建，用于在聚四氟乙烯管 (PTFE) 下方固定六个可调节的永磁体，以将 MNP 生物催化剂固定在管式反应器内。锚定的 CaLB-MNP 在管中形成反应室，用于使流体通过 MNP 生物催化剂并在其上方，从而增加流体流动期间的混合并导致CaLB对MNP的活性增强。4-(morpholin-4-yl)butan-2-ol (±)-的对映异构体选择性酰化图1是粘液溶解药物Fedrilate的手性醇成分，由CaLB-MNPs在U形反应器中进行。将 U 形反应器中的 CaLB-MNPs 在间歇反应中与冻干 CaLB 和使用相同反应组合物的 CaLB-MNPs 进行比较，相同数量的 CaLB 在流动模式下表现出相似或更高的活性，并且与比较的活性相比具有更高的活性为冻干粉末形式。U 形永磁体设计代表了基于 MNP 的流动微反应器的通用且易于访问的实施方案，可用于许多生物转化并减少昂贵且耗时的下游工艺。