Covalent Immobilization of Candida antarctica Lipase B on Functionalized Hollow Mesoporous Silica Nanoparticles

Comparison of covalent and in situ immobilization of Candida antarctica lipase A on a flexible nanoporous material

In this study, Candida antarctica lipase A, which has a unique applicability for the conversion of highly branched and bulky substrates, was subjected to immobilization on the flexible nanoporous MIL-53(Fe) by two approaches: covalent coupling and in situ immobilization method. The pre-synthesized support under ultrasound irradiation was incubated with N,N-dicyclohexylcarbodiimide to mediate the covalent attachment between the carboxylic groups on the support surface and amino groups of enzyme molecules. The in situ immobilization in which the enzyme molecules directly were embedded into the metal-organic framework was performed under mild operating conditions in a facile one-step manner. Both immobilized derivatives of the enzyme were characterized by scanning electron microscopy, X-ray diffraction, thermogravimetric analysis, FT-IR spectra, and energy-dispersive X-ray spectroscopy. In the in situ immobilization method, the enzyme molecules were efficiently encapsulated within the support with a high loading capacity (220 ± 5 mg/g support). On the other hand, the covalent attachment resulted in immobilizing much lower concentrations of the enzyme (20 ± 2.2 mg/g support). Although both immobilized derivatives of lipase showed broader pH and temperature tolerance relative to the soluble enzyme, the biocatalyst, which was prepared through in situ method, was more stable at elevated temperatures than the covalently immobilized lipase. Furthermore, in situ immobilized derivatives of Candida antarctica lipase A could be efficiently reused for at least eight cycles (> 70% of retained activity). In contrast, its covalently immobilized counterpart showed a drastic decrease in activity after five cycles (less than 10% of retained activity at the end of 6 rounds).

Scalability of U-Shape Magnetic Nanoparticles-Based Microreactor–Lipase-Catalyzed Preparative Scale Kinetic Resolutions of Drug-like Fragments

The production of active pharmaceutical ingredients (APIs) and fine chemicals is accelerating due to the advent of novel microreactors and new materials for immobilizing customized biocatalysts that permit long-term use in continuous-flow reactors. This work studied the scalability of a tunable U-shape magnetic nanoparticles (MNPs)-based microreactor. The reactor consisted of a polytetrafluoroethylene tube (PTFE) of various inner diameters (ID = 0.75 mm, 1.50 mm, or 2.15 mm) and six movable permanent magnets positioned under the tube to create reaction chambers allowing the fluid reaction mixture to flow through and above the enzyme-loaded MNPs anchored by permanent magnets. The microreactors with various tube sizes and MNP capacities were tested with the preparative scale kinetic resolution of the drug-like alcohols 4-(3,4-dihydroisoquinolin-2(1H)-yl)butan-2-ol (±)-1a and 4-(3,4-dihydroquinolin-1(2H)-yl)butan-2-ol (±)-1b, utilizing Lipase B from Candida antarctica immobilized covalently onto MNPs, leading to highly enantioenriched products [(R)-2a,b and (S)-1a,b]. The results in the U-shape MNP flow reactor were compared with reactions in the batch mode with CaLB-MNPs using similar conditions. Of the three different systems, the one with ID = 1.50 mm showed the best balance between the maximum loading capacity of biocatalysts in the reactor and the most effective cross-section area. The results showed that this U-shaped tubular microreactor might be a simple and flexible instrument for many processes in biocatalysis, providing an easy-to-set-up alternative to existing techniques.

Immobilization of Lipase from Candida antarctica B (CALB) by Sol-Gel Technique Using Rice Husk Ash as Silic Source and Ionic Liquid as Additive

This work presents the immobilization in situ of commercial lipase from Candida antarctica B (CALB) by the sol-gel technique (xerogel) using silica from rice husk ash (RHA) as a source of silicon. It was used the Ionic Liquid (IL) 1-octyl-3-methylimidazolium bromide (C8MI.Br) as additive. The immobilized derivatives were characterized per SEM, XRD, and per method BET. The enzymatic activity of xerogels was evaluated with different tests, these being the reactional thermal analysis, immobilization yield, and operational and storage stability. The XDR showed that the obtained xerogels have halos in the region between 15 and 35° (2θ) what characterizes it as amorphous materials. The SEM analysis of xerogel shows irregular particles with dimensions less than 20 μm. The immobilized presented an esterification activity (EA) with 263.2 and 213.8 U/g, with and without IL, respectively, higher than the free enzyme (169.6 U/g). The immobilized, with and without IL, presented a significant improvement in the activity performance in relation to free enzyme for the three reactional temperatures (40, 60, and 80 °C) evaluated. The operational stability demonstrated that is possible to use xerogel without ionic liquid for 17 recycles and 21 recycles in IL presence. This methodology allows the preparation of new highly active and selective enzyme catalysts using the rice husk ash as a source of silicon, and the ionic liquid [C8MI]Br as additive. Furthermore, the new materials can provide greater viability in the processes, ensuring longer catalyst life.