N,P,or S-doped carbon nanotubes as dual mimics of NADH oxidase and cytochrome c reductase

Most nanozyme research is limited to oxidase and peroxidase.Here,we reported the N,P,or S doped carbon nanotubes(CNTs)for enzyme mimics of nicotinamide adenine dinucleotide(NADH)oxidase and cytochrome c(Cyt c)reductase.Through the doping of N element,the NADH oxidase-like activity of CNTs is highly improved,the maximum initial velocity for N doped CNT(N-CNT)is increased by 4.28 times compared to that before the modification.Through the analysis of NADH oxidation products,we found that biologically active NAD+was produced,the oxygen was selectively reduced to water or hydrogen peroxide,which is consistent with natural NADH oxidase.Furthermore,we found for the first time that carbon nanotubes can promote the transfer of electrons from NADH to Cyt c,thereby can mimic the properties of Cyt c reductase.

Cadmium sulfide as bifunctional mimics of NADH oxidase and cytochrome c reductase takes effect at physiological pH

Recently,a study of mimic enzyme has received more attentions.However,the investigation on the oxidoreductase activity of electron mediators in the biological respiratory chain is still rare.Herein,we found that cadmium sulfide(CdS)nanorods can catalyze the formation of superoxide anions.Due to the role of the photo-generated holes and the nicotinamide adenine dinucleotide(NADH)oxidation promoted by superoxide anion(O_(2)^(•−)),the CdS exhibits NADH oxidase-like activity and can be coupled with dehydrogenase to realize the recycling of NADH.It is worth mentioning that the bio-electron acceptor,cytochrome c(Cyt c),as a chromogenic substrate,can accept electrons transferred from O_(2)^(•−),which demonstrates the Cyt c reductase-like activity of CdS under physiological pH conditions.For different substrates,O_(2)^(•−)induced from CdS show oxidizing capacity for NADH and reducing capacity for Cyt c,which provides a new perspective for the in-depth study of new nanozyme.