Assembly of an artificial biomembrane by encapsulation of an enzyme, formaldehyde dehydrogenase, into the nanoporous-walled silica nanotube-inorganic composite membrane

We prepared silica nanotube with nanochannel-wall in the columnar pores of a commercial anodic alumina membrane (F127-MST), and then made up an artificial biomembrane consisting of a hierarchical structure by introducing an enzyme, formaldehyde dehydrogenase, into the silica nanochannels. The formaldehyde dehydrogenase confined in membrane showed a very high activity for the reduction of NAD⁺ similar to that of the native, besides much higher electron transfer to the electrode than the native. At the same time, we clarified that the encapsulation of enzymes into the nanochannels enables enzymes to accumulate in high density without aggregation and be arranged regularly. These results indicate that F127-MST can provide a favorable method for enzyme immobilization on the electrode.