Catechol monophosphate as a new substrate for screen-printed amperometric biosensors with immobilized phosphatases

Catechol monophoshate (CMP) is proposed as a new substrate for determination of activity of alkaline phosphatase and protein phosphatase for amperometric biosensors. The product of its enzymatic hydrolysis, catechol, is oxidized at a graphite screen-printed electrode in the potential range from +0.2 to 0.5 V versus Ag/AgCl depending on pretreatment and modification of the surface of the working electrode. A linear response in chronoamperometric measurements of catechol carried out in a drop of solution covering three electrodes of screen-printed strip, was observed for catechol up to μM, and a limit of detection of 0.15 μM was found. The obtained results indicate that CMP can be successfully used as a substrate for determination of hepatotoxic microcystins with screen-printed biosensor with immobilized commercial protein phosphatase PP-2A with a LOD in the sub-ppb range.