Discipline: Chemistry and Chemical Sciences
Subcategory: Chemistry (not Biochemistry)
Lydia Mensah - University of Michigan, Ann Arbor
Co-Author(s): Michael Holzinger and Fabien Giroud, Université Joseph Fourier, Grenoble, France
There has been a new push to design enzymatic biofuel cells. Biofuels cells can convert chemical energy to electrical energy from the oxidation of carbohydrates. They are simple in design, and can operate in mild and complex conditions, which is why they would be instrumental for new implantable devices. In a typical carbohydrate/O2 biofuel cell, oxygen reduction occurs at the biocathode while the fuel (carbohydrate) is being oxidized at the anode. The enzymatic biofuel cell developed in the laboratory utilizes glucose oxidase to oxidize glucose at the bioanode. However, the ability to create an enzyme-based biofuel cell with glucose oxidase (GOx) is set back by the Flavin Adenine Dinucleotide (FAD) because it is difficult for the electrons to reach the active site of the flavin, which is deeply bound in its structure to oxidize it. Riboflavin, Vitamin B2, is a water-soluble vitamin that plays a roll in cell metabolism. It is also a key central component of the FAD since it is the electroactive part of the cofactor. In this study it was hypothesized that riboflavin would be a good mediator because not only does it contain a flavin, its potential is higher than FAD. Therefore, VB2 was studied as a redox mediator for GOx at the anode of the biofuel cell. A glassy carbon electrode was modified by depositing multi-walled carbon nanotubes (MWCNTs) on the surface and incubated with pyrene through pi-pi stacking on CNTs. Pyrene derivatives were used in this study to immobilize riboflavin depending on their specific groups (-COOH, -NH2, -OH, etc…). It acted as an anchor to keep the riboflavin at the electrode. The goal was to have riboflavin immobilized on the surface of the CNTs to use as an electron mediator to shuttle the electrons gathered from glucose oxidation to the electrode. The results of the experiments conducted show that the oxidation and reduction of riboflavin is a reversible process with oxidation occurring ~-0.4V and reduction at ~-0.5V in a 0.1mM VB2 solution. Future research involves understanding how deposition preparation and techniques influence electrochemical results and can x-ray diffraction be used to determine the surface composition of electrodes.Not Submitted
Funder Acknowledgement(s): This study was supported by NSF iREU grant CHE 1263336 and is gratefully acknowledged.
Faculty Advisor: Michael Holzinger, firstname.lastname@example.org