Constructing spatially separated multienzyme system through bioadhesion-assisted bio-inspired mineralization for efficient carbon dioxide conversion.

A facile and green bioadhesion-assisted bio-inspired mineralization (BABM) approach is proposed to construct spatially separated multienzyme system for conversion of carbon dioxide to formaldehyde. Specifically, formate dehydrogenase is entrapped accompanying the formation of titania nanoparticles (NPs) through bio-inspired titanification. After in situ surface functionalization of NPs with oligodopa, formaldehyde dehydrogenase is immobilized on the surface of NPs through amine-catechol adduct reaction. Compared to co-immobilized and free multienzyme system, the spatially separated multienzyme system exhibits significantly enhanced formaldehyde yield, selectivity and initial specific activity. The influence of particle size on the enzyme activity reveals that the formaldehyde yield (80.9%, 52.9%, 46.4%), selectivity (92.7%, 86.6%, 85.1%) and initial specific activity (1.87, 1.31, 0.29 U mg(-1)) all decreased as the NPs particle size increased from 75, 175 to 375 nm. After storing for 20 days at 4 °C, this multienzyme system retains as high as 70% of its initial activity.