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Virus-like organosilica nanoparticles for lipase immobilization: Characterization and biocatalytic applications

Jiang, Yanjun, Liu, Huan, Wang, Lihui, Zhou, Liya, Huang, Zhihong, Ma, Li, He, Ying, Shi, Lujing, Gao, Jing
Biochemical engineering journal 2019 v.144 pp. 125-134
Pseudozyma antarctica, alcohols, carboxylic ester hydrolases, esterification, glutaraldehyde, hydrolysis, hydrophobic bonding, hydrophobicity, immobilized enzymes, levulinic acid, nanoparticles, nanotubes, pH, porous media, response surface methodology, silica, solvents, storage quality, temperature, thermal stability
Hydrophobic virus-like organosilica nanoparticles (VOSNs) with a spherical core formed by mesoporous organosilica surrounded by epitaxial perpendicular nanotubes were successfully synthesized for the first time. These hydrophobic VOSNs were used for the immobilization of the lipase B from Candida antarctica (CALB) via covalent binding method, where glutaraldehyde was used as a spacer to form covalent bonds connect between the enzyme and support. Under optimized immobilization conditions, the specific hydrolytic activity which determined via the hydrolysis of p-NPP was 23200 U/gsupport, and the maximum CALB loading was 115.6 mg/gsupport. Compared to virus-like silica nanoparticles (VSNs), the hydrophobic VOSNs protected the CALB active conformation from a hazardous external environment due to stronger hydrophobic interactions between the VOSNs and CALB molecule. Thus, compared with CALB@VSNs and free lipase, CALB@VOSNs exhibited better pH, thermal stability, organic solvents tolerance and storage stability. The CALB@VOSNs was used to catalyze the esterification reaction of levulinic acid (LA) and n-lauryl alcohol, which was optimized by a response surface method. Under the optimal conditions (temperature, 51.2 °C; LA: n-lauryl alcohol, 1:11.5; time, 22.6 h), the CALB@VOSNs still retained 75.7% of the LA conversion, whereas the N435 only retained 29.8% of the conversion after 9 cycles. These results showed that hydrophobicity VOSNs could be an efficient support to prepare immobilized enzymes as well as to improve the properties of enzymes.