Maltodextrin-powered enzymatic fuel cell through a non-natural enzymatic pathway

Enzymatic fuel cells (EFCs) use a variety of fuels to generate electricity through oxidoreductase enzymes, such as oxidases or dehydrogenases, as catalysts on electrodes. We have developed a novel synthetic enzymatic pathway containing two free enzymes (maltodextrin phosphorylase and phosphoglucomutase) and one immobilized glucose-6-phosphate dehydrogenase that can utilize an oligomeric substrate maltodextrin for producing electrons mediated via a diaphorase and vitamin K3 electron shuttle system. Three different enzyme immobilization approaches were compared based on electrostatic force entrapment, chemical cross-linking, and cross-linking with the aid of carbon nanotubes. At 10 mM glucose-6-phosphate (G6P) as a substrate concentration, the maximum power density of 0.06 mW cm−2 and retaining 42% of power output after 11 days were obtained through the method of chemical cross-linking with carbon nanotubes, approximately 6-fold and 3.5-fold better than those of the electrostatic force-based method, respectively. When changed to maltodextrin (degree of polymerization = 19) as the substrate, the EFC achieved a maximum power density of 0.085 mW cm−2. With the advantages of stable, low cost, high energy density, non-inhibitor to enzymes, and environmental friendly, maltodextrin is suggested to be an ideal fuel to power enzymatic fuel cells.

► Oligosaccharide maltodextrin can power enzymatic fuel cell (EFC).
► An enzymatic pathway based on maltodextrin is designed to generate electrons.
► Chemical linking plus CNT enhances power output and prolongs lifetime of EFC.