Ultrasound-Assisted Interfacial Immobilization of Lipase on Hollow Mesoporous Silica Spheres in a Pickering Emulsion System: A Hyperactive and Sustainable Biocatalyst

Lipase immobilization processes have the potential to drive large-scale industrial applications through cost savings. Among them, the Pickering emulsion system has recently emerged as an ecofriendly technique for enhanced enzymatic activity. In this study, a novel and facile immobilization of lipase in an ultrasound-assisted Pickering emulsion system was developed. The lipase loading amount and yield was 177.3 mg/g and 41.3%, respectively. In the enzymatic synthesis of four sterol lipoates, the immobilized lipase (UIP-HMSS@CRL) achieved the highest catalytic efficiency (CE) of 6.4 mmol/g·h among the reported methods, which was 9.1-fold higher than that of free lipase and 32.0-fold higher than that of previous methods. UIP-HMSS@CRL performed with much higher Vm and lower Km, indicating the excellent catalytic rate and stronger affinity. Moreover, UIP-HMSS@CRL displayed satisfying thermal stability and recyclability, retaining 88.6% of enzyme activity after 10 cycles. The lipase lid was opened at the oil–water interface by both ultrasound and interfacial synergistic activation effect, which provided easier access to an active site and thus achieved excellent catalytic performance. This ultrasound-assisted interface immobilization would open new opportunities for preparation of high-performance and sustainable biocatalysts.