One-pot immobilization of formate dehydrogenase on silica nanoparticles based on catechol chemistry with or without polyethyleneimine

Converting carbon dioxide into formic acid with formate dehydrogenase (FDH) as a catalyst is a gentle and eco-friendly process that not only conserves energy and reduces emissions but transforms waste into valuable resource. Enzyme immobilization is a common strategy for improving the stability and recyclability of enzyme, however, the procedures are usually complicated that include surface modification and binding reactions in order to form reliable linkages. Co-deposition of polydopamine (PDA) with polyethyleneimine (PEI) is a popular surface modification approach in versatile fields, but their co-deposition with enzymes is rarely reported. Herein, one-pot immobilization of FDH on SiO₂ nanoparticles based on catechol chemistry was attempted for the first time with or without PEI, and the resultant immobilized enzymes, FDH/PDA/PEI-SiO₂ and FDH/PDA-SiO₂, were characterized, and the effects of the composition and deposition conditions on the catalytic performance were investigated. FDH/PDA-SiO₂ exhibited a higher apparent specific activity than FDH/PDA/PEI-SiO₂, which was separately 0.167 and 0.136 mM/h/mg. The activity recovery rate was 464% and 378% of that of free enzyme. After 5 cycles, their relative activity was 82.3% and 87.4%. This research is significant in presenting a simple and high-efficient one-pot immobilization method that can be extended to other kinds of enzymes.