Bioinspired synthesis of micelle-templated ultrathin silica-layered mesoporous nanoparticles with enhanced mass transfer and stability for biocatalysis

Abstract

Bioinspired enzyme encapsulation technologies have received increasing attention in sustainable development owing to the enzyme protection from external stressors while mimicking the cellular environment and structure. In this study, we developed a diatom-inspired synthesis of ultrathin silica-layered nanoparticles directed by silica-forming R5 peptide- and carbonic anhydrase (CA)-functionalized micelles. Each CA and R5 peptide was covalently conjugated with N-hydroxysuccinimide (NHS)-ester-modified hydrophilic ends of the triblock copolymer F127 (F127–CA and F127–R5). F127–CA/R5 micelles were prepared by controlling the molar ratio of F127–CA and F127–R5. F127–CA/R5 micelle@silica nanoparticles (SiNPs) were synthesized through R5 peptide-catalyzed silicification of the F127–CA/R5 micelle in a two-phase system. F127–CA/R5 micelle@SiNPs exhibited uniform and monodisperse particles with a size of 17 nm, indicating the formation of a ∼1.5-nm ultrathin and mesoporous silica layer compared with F127–CA/R5 micelle. F127–CA/R5 micelle@SiNPs exhibited almost identical KM and kcat values in CO2 hydration activity compared with the free enzyme. In addition, F127–CA/R5 micelle@SiNPs also showed enhanced stability compared to free ngCA under the operation condition of CO2 capture and sequestration with good storage stability. These results indicated that an ultrathin and mesoporous silica layer on the micelle could protect enzymes from external environments while minimizing limited mass transfer. Thus, our strategy could offer a new direction for enzyme-based green chemistry in practical applications, providing enhanced mass transfer and stability.