Highly sensitive electrochemical determination of Escherichia coli density using tyrosinase-based chemically amplified biosensor

Tyrosinase-based chemically amplified biosensors, based on a substrate recycling of polyphenolic compounds driven by tyrosinase-catalyzed oxidation and chemical reduction of o-quinones by L-ascorbic acid (AsA), has been applied for the highly sensitive electrochemical determination of the Escherichia coli (E. coli) density. The amplified signal of the tyrosinase-coupling electrode due to the recycling of tyrosinase-active polyphenolic compounds, which is microbially generated from the salicylic acid derivatives by the metabolic pathway of E. coli, depends considerably on the E. coli density ranging from 103 to 104 cells/ml level.