In a biosensor for measuring a specific substance in a liquid sample, one or a combination of sugar alcohol, metallic salt, organic acid or organic acid salt which has at least one carboxyl group in a molecule, and organic acid or organic acid salt which has at least one carboxyl group and one amino group in a molecule, is included in a reagent layer provided on electrodes, thereby providing a highly-accurate biosensor which is excellent in stability and has high response (sensitivity, linearity) of the sensor to the substrate concentration.
1. A biosensor for measuring the concentration of a specific substance in a sample solution, the biosensor comprising
electrodes comprising at least a working electrode and a counter electrode provided on an insulating support; and
a reagent layer which reacts with the specific substance in the sample solution;
wherein the reagent layer comprises an enzyme, an electron transfer agent, and an organic acid or organic acid salt which has at least one carboxyl group;
the organic acid is aliphatic carboxylic acid, carbocyclic carboxylic acid, heterocyclic carboxylic acid, a substitution product, or derivative of the organic acid;
the carboxylic acid is malonic acid, succinic acid, glutaric acid, adipic acid, maleic acid, fumaric acid, benzoic acid, phthalic acid, isophthalic acid, terephthalic acid, 2-phthalic acid, nicotinic acid, isonicotinic acid, their salt, or a combination thereof; and
the enzyme is glucose dehydrogenase.
2. The biosensor as defined in claim 1 , wherein the reagent layer comprises a hydrophilic polymer.
3. A biosensor for measuring the concentration of a specific substance in a sample solution, the biosensor comprising
electrodes comprising at least a working electrode and a counter electrode provided on an insulating support; and
a reagent layer which reacts with the specific substance in the sample solution;
wherein the reagent layer includes an enzyme, an electron transfer agent, and an organic acid or organic acid salt which has at least one carboxyl group and one amino group;
the organic acid is an amino acid, a substitution product of an amino acid, sarcosine or betaine;
the amino acid is alanine, valine, leucine, isoleucine, serine, threonine, methionine, asparagine, glutamine, arginine, lysine, histidine, phenylalanine, tryptophan, proline, their salt, or a combination thereof; and
the enzyme is glucose dehydrogenase.
4. The biosensor as defined in claim 3 , wherein the reagent layer comprises a hydrophilic polymer.