title: Encapsulation of enzyme via one-step template-free formation of stable organic-inorganic capsules: A simple and efficient method for immobilizing enzyme with high activity and recyclability.
abstract: Enzyme encapsulation is a simple, gentle, and general method for immobilizing enzyme, but it often suffers from one or more problems regarding enzyme loading efficiency, enzyme leakage, mechanical stability, and recyclability. Here we report a novel, simple, and efficient method for enzyme encapsulation to overcome these problems by forming stable organic-inorganic hybrid capsules. A new, facile, one-step, and template-free synthesis of organic-inorganic capsules in aqueous phase were developed based on PEI-induced simultaneous interfacial self-assembly of Fmoc-FF and polycondensation of silicate. Addition of an aqueous solution of Fmoc-FF and sodium silicate into an aqueous solution of PEI gave a new class of organic-inorganic hybrid capsules (FPSi) with multi-layered structure in high yield. The capsules are mechanically stable due to the incorporation of inorganic silica. Direct encapsulation of enzyme such as epoxide hydrolase SpEH and BSA along with the formation of the organic-inorganic capsules gave high yield of enzyme-containing capsules (∼1.2 mm in diameter), >90% enzyme loading efficiency, high specific enzyme loading (158 mg protein g(-1) carrier), and low enzyme leakage (<3% after 48 h incubation). FPSi-SpEH capsules catalyzed the hydrolysis of cyclohexene oxide to give (1R, 2R)-cyclohexane-1,2-diol in high yield and concentration, with high specific activity (6.94 U mg(-1) protein) and the same high enantioselectivity as the free enzyme. The immobilized SpEH demonstrated also excellent operational stability and recyclability: retaining 87% productivity after 20 cycles with a total reaction time of 80 h. The new enzyme encapsulation method is efficient, practical, and also better than other reported encapsulation methods.
authors.affiliation: Department of Chemical and Biomolecular Engineering, National University of Singapore, 4 Engineering Drive 4, Singapore 117585, Singapore.
authors.forename: Renliang
authors.initials: R
authors.lastname: Huang
authors.forename: Mengyun
authors.initials: M
authors.lastname: Wu
authors.forename: Mark J
authors.initials: MJ
authors.lastname: Goldman
authors.forename: Zhi
authors.initials: Z
authors.lastname: Li
mesh_terms: D002214:Capsules / Q000138:chemical synthesis*; D053138:Cyclohexenes / Q000378:metabolism; D004795:Enzyme Stability; D004800:Enzymes, Immobilized / Q000737:chemistry* / Q000378:metabolism*; D004851:Epoxide Hydrolases / Q000737:chemistry* / Q000378:metabolism*; D005449:Fluorenes / Q000737:chemistry; D006868:Hydrolysis; D011094:Polyethyleneimine / Q000737:chemistry; D017640:Silicates / Q000737:chemistry
chemical_list: D002214:Capsules; D053138:Cyclohexenes; D004800:Enzymes, Immobilized; D005449:Fluorenes; D017640:Silicates; C007193:cyclohexene oxide; D011094:Polyethyleneimine; D004851:Epoxide Hydrolases
keywords: biocatalysis; encapsulation; enzyme immobilization; epoxide hydrolase; organic-inorganic capsule; supramolecular self-assembly