Electron mediator and electrochemical biosensor employing the same

A composition for forming a detecting reagent layer comprising:

• an electron mediator system comprising a first transition metal complex and a second transition metal complex, wherein a working potential of the electron mediator system is substantially the same as a molar average of a working potential of the first transition metal complex and a working potential of the second transition metal complex;
• an enzyme;
• and
• a carrier,
• wherein the first transition metal complex comprises a ligand comprising a thiophene group.

A biosensor comprising:

• a working electrode formed on an insulating substrate;
• a counter electrode formed on the insulating substrate;
• and
• a detecting reagent layer contacting the working electrode and the counter electrode,
• wherein the detecting reagent layer comprises an electron mediator system that comprises a first transition metal complex and a second transition metal complex, wherein a working potential of the electron mediator system is substantially the same as a molar average of a working potential of the first transition metal complex and a working potential of the second transition metal complex,
• wherein the first transition metal complex comprises a ligand comprising a thiophene group.