Electron mediator, electron mediator immobilized electrode, and biofuel cell using the electrode
An object of the present invention is to provide a highly functional mediator capable of smoothly proceeding electron transfer between an electrode and a biocatalyst based on the premise that the mediator excels in safety and cost and to provide an electrode and a cell with sufficient amount of such a mediator molecule immobilized efficiently and strongly. The present invention provides a mediator mediating electron transfer between an enzyme and an electrode and containing a quinone molecule derivative, in particular, a mediator containing a VK 3 derivative. In addition, the present invention provides an electrode and a biofuel cell to which those mediators are applied.
1. An electrode comprising
a mediator, said mediator comprising a quinone molecule derivative,
a crosslinking agent, and
a polymer or a biopolymer,
wherein
the quinone molecule derivative is a quinone molecule modified with at least one functional group bonded with (i) the polymer or the biopolymer or (ii) the crosslinking agent;
the mediator is immobilized through bonding of the at least one modified functional group of the quinone molecule derivative; and
the mediator mediates electron transfer between at least one enzyme and an electrode.
2. An electrode according to claim 1 , wherein the at least one enzyme is immobilized.
3. An electrode according to claim 2 , wherein the at least one immobilized enzyme is diaphorase.
4. An electrode according to claim 2 comprising at least two immobilized enzymes, wherein the at least two immobilized enzymes are diaphorase and dehydrogenase.
5. An electrode according to claim 4 , wherein the dehydrogenase is glucose dehydrogenase.
6. An electrode according to claim 4 or 5 , further comprising immobilized co-enzyme NADH.
7. An electrode according to claim 2 comprising the mediator and the enzyme immobilized on the electrode by a polymer and a crosslinking agent.
8. An electrode according to claim 7 , wherein the polymer is polyvinylimidazole.
9. An electrode according to claim 7 or 8 , wherein the crosslinking agent is polyethylene glycol diglycidyl ether (PEGDGE).
10. An electrode according to claim 1 , used for one of a biofuel cell and a biosensor.
11. The electrode according to claim 1 wherein the quinone molecule derivative is a naphthoquinone molecule derivative.
12. The electrode according to claim 11 wherein the naphthoquinone molecule derivative is at least one naphthoquinone molecule chosen from the group consisting of a sodium anthraquinone-2-sulfonate (AQS) derivative and a 2-methyl-1,4-naphthoquionone (VK3) derivative.
13. The electrode according to claim 11 , wherein the naphthoquinone molecule derivative is a 2-methyl-1,4-naphthoquinone (VK3) derivative.
14. The electrode according to claim 13 , wherein the 2-methyl-1,4-naphthoquinone (VK3) derivative is 2-methyl-1,4-naphthoquinone (VK3) modified with at least one functional group, wherein the at least one functional group is capable of bonding with a polymer or an enzyme.
15. The electrode according to claim 14 , wherein the at least one functional group is selected from the group consisting of an amino group, a carboxyl group, a chloroformyl group, a succinimide oxycarbonyl group, an alkyl metal sulfosuccinimide oxycarbonyl group, a pentafluorophenyl oxycarbonyl group, a p-nitrophenyl oxycarbonyl group, a hydroxyl group, a formyl group, a halogen group, a maleimide group, an isothiocyanate group, and an oxiranyl group.
16. The electrode according to claim 15 , wherein the 2-methyl-1,4-naphthoquinone (VK3) derivative is modified with the at least one functional group at a 2-position and/or a 3-position of the naphthoquinone.
17. The electrode according to claim 16 , wherein the 2-methyl-1,4-naphthoquinone (VK3) derivative is a 3-methyl-1,4-naphthoquinone modified with the at least one functional group at the 2-position of the naphthoquinone.
18. The electrode according to claim 17 , further comprised of a spacer molecule between the functional group and the 2-position of the naphthoquinone.
19. The electrode according to claim 18 , wherein the spacer molecule is selected from the group consisting of a hydrocarbon linear chain, a polyoxyethylene linear chain, a polyethylene glycol chain, and a polypropylene glycol chain.
20. The electrode according to claim 19 , wherein the spacer molecule is a hydrocarbon linear chain alkyl group.
21. The electrode according to claim 14 , wherein the 2-methyl-1,4-naphthoquinone (VK3) derivative is one or more kinds of a quinone molecule selected from the group consisting of 2-(3-carboxypropyl)-3-methyl-1,4-naphthoquinone (CPVK3) represented by the following formula (1), 2-{3-[N-(2-aminoethyl)aminocarbonyl]propyl}-3-methyl-1,4-naphthoquinone (AEACPVK3) represented by the following formula (2), and 2-(3-aminopropyl)-3-methyl-1,4-naphthoquinone (APVK3) represented by the following formula (3):
22. The electrode according to claim 21 , wherein the 2-methyl-1,4-naphthoquinone (VK3) derivative is 2-(3-carboxypropyl)-3-methyl-1,4-naphthoquinone (CPVK3) represented by the following formula (1):
23. An electrode according to claim 1 comprising a polymer, wherein
the modified functional group of the quinone molecule derivative of the mediator is bonded to the crosslinking agent; and
the crosslinking agent is bonded to the polymer.
24. An electrode according to claim 23 , wherein
the quinone molecule derivative is a quinone molecule modified with an amino functional group;
the polymer comprises an imidazole functional group;
the crosslinking agent comprises at least two epoxy functional group;
the amino functional group of the quinone molecule derivative bonds with a first epoxy functional group of the crosslinking agent;
the imidazole functional group of the polymer bonds with the second epoxy functional group of the crosslinking agent;
the bonded mediator, crosslinking agent, and polymer form an insoluble gel; and
the insoluble gel is immobilized on the electrode.
25. An electrode according to claim 23 , wherein the polymer is polyvinylimidazole.
26. An electrode according to claim 23 , wherein the crosslinking agent is polyethylene glycol diglycidyl ether (PEGDGE).
27. An electrode apparatus comprising
an electrode with an electrode surface;
a mediator comprising a quinone molecule derivative consisting of 2-(3-carboxypropyl)-3-methyl-1,4-naphthoquinone (CPVK3);
a diaphorase enzyme; and
a nicotinamide adenine dinucleotide molecule;
wherein
the mediator and the diaphorase enzyme are immobilized on the electrode surface by a polyvinylimidazole polymer and a polyethylene glycol diglycidyl ether (PEGDGE) crosslinking agent;
the immobilized diaphorase enzyme can catalyze electron transfer between the immobilized nicotinamide adenine dinucleotide molecule and the immobilized mediator; and
the immobilized mediator mediates electron transfer between the immobilized diaphorase enzyme and the electrode.
28. The electrode of claim 27 further comprising a dehydrogenase enzyme,
wherein
the dehydrogenase enzyme is immobilized on the electrode surface by the polyvinylimidazole polymer and the PEGDGE crosslinking agent;
the immobilized dehydrogenase enzyme can catalyze electron transfer between a biofuel and an oxidized form of the immobilized nicotinamide adenine dinucleotide molecule to form a reduced form of the immobilized nicotinamide adenine dinucleotide molecule; and
the immobilized diaphorase enzyme can catalyze electron transfer between the reduced form of the immobilized nicotinamide adenine dinucleotide molecule and the immobilized mediator.