Facile mussel-inspired polydopamine-coated 3D-printed bioreactors for continuous flow biocatalysis

Continuous flow biocatalysis has been a challenge in the biocatalysis area. To enable flow biocatalysis, enzyme immobilization techniques, as well as support materials, have been studied. Herein, this research employed a 3D printer, mussel-inspired polydopamine (PDA), and an enzyme to create PDA-coated 3D-printed bioreactors for continuous flow biocatalysis. Both batch and microfluidic bioreactors were fabricated using a 3D printer, functionalized by PDA, glutaraldehyde, and polyethylenimine, and thereby used for enzyme immobilization. This research used a novel and robust alcohol dehydrogenase, an acetophenone reductase from Geotrichum candidum ( Gc APRD), as an enzyme model. First, we succeeded in immobilizing Gc APRD on the PDA-coated 3D-printed batch bioreactors. The immobilized Gc APRD could be recycled up to 4 times to reduce acetophenone with excellent enantioselectivity (ee > 99%, S ). Next, continuous flow processes were successfully established using the PDA-coated 3D-printed microfluidic bioreactors with immobilized Gc APRD. The reduction of acetophenone proceeded smoothly to produce an enantiopure alcohol, ( S )-1-phenylethanol, with excellent enantioselectivity up to 117-144 h. These findings opened up a new step in flow biocatalysis development, which has the feasibility of scaling up for further industrial uses. Enantiopure alcohol production by a flow system of 3D-printed bioreactor with immobilized Geotrichum candidum acetophenone reductase ( Gc APRD).