Renewable-Reagent Enzyme Inhibition Sensor for Remote Monitoring of Cyanide

A renewable-reagent flow probe has been developed for the remote electrochemical biosensing of enzyme inhibitors. The new submersible device addresses the challenges of continuously replacing the inhibited enzyme and consumed substrate. The internal delivery of microliter enzyme and substrate solutions is coupled to an in situ microdialysis sampling of the toxin, and an amperometric detection of the enzymatically generated product. The new concept is demonstrated for the detection of micromolar concentrations of free cyanide in the presence of the enzyme tyrosinase and its catechol substrate. The optimization of various physical and chemical parameters has resulted in a low detection limit of 2 × 10−6 M cyanide and good precision (RSD = 5%). The new device holds great promise for in situ environmental and industrial monitoring of toxins.