Mono- and heterofunctionalized silica magnetic microparticles (SMMPs) as new carriers for immobilization of lipases

• Published in: Journal of molecular catalysis. B, Enzymatic Enzymatic, 2016-11, Vol.133, p.S491-S499
• Main Authors: de Lima, Lionete Nunes, Vieira, Gustavo Nakamura Alves, Kopp, Willian, Tardioli, Paulo Waldir, Giordano, Raquel L.C.
• Format: Article
• Language: English
• Subjects: Candida antarctica lipase B; Heterofunctionalization; Silica magnetic microparticles; Xylose fatty acid ester
• ISSN: 1381-1177; 1873-3158
• DOI: 10.1016/j.molcatb.2017.04.002

[Display omitted] •Silica magnetic microparticle (SMMP) were modified with octyl and aldehyde groups.•Lipase B from Candida antarctica was immobilized on modified SMMPs.•Syntheses of xylose esters were optimized by response surface methodology.•Xylose conversion around 65% was achieved at 55°C after 24h reaction.•Biocatalysts remained active by ten 48 h-cycles of xylose ester synthesis at 46°C. In order to improve economic viability of an enzymatic process, the use of an operationally stable and low-cost biocatalyst is encouraged. Although the immobilization of lipases is widely reported, the search for new supports and immobilization protocols with better properties is still important. In this study, mono- and heterofunctionalized silica magnetic microparticles (SMMPs) were synthetized for immobilization of lipase B from Candida antarctica (CALB). The SMMPs were prepared in a micro-emulsion system containing sodium silicate and superparamagnetic iron oxide nanoparticles, followed by chemical modification with octyl groups and octyl plus aldehyde groups. These supports allowed the immobilization of CALB by hydrophobic adsorption or hydrophobic/covalent linkages, achieving immobilization yield of 88% and recovered activities of 128% and 59%, respectively. The performance of the magnetic biocatalysts was evaluated in the synthesis of xylose fatty acid esters (laurate or oleate) in tert-butyl alcohol medium, yielding around 60% conversion after 48h under optimized conditions (xylose/fatty acid molar ratio of 1:0.2, 55°C, and activity load of 37.5U/g). The magnetic biocatalyst was used in 10 reaction cycles of 48h at 46°C maintaining high xylose conversions. Besides, the biocatalyst might be easily and quickly recovered from the reaction medium by an external magnetic field, an operational advantage in the case of viscous and complex media, e.g., medium containing insoluble sugars and molecular sieves.