Toxin detection using a tyrosinase-coupled oxygen electrode

Abstract

An enzyme-based "electrochemical canary" is described for the detection of cyanide. The sensing system imitates cyanide's site of toxicity in the mitochondria. The terminal sequence of electron transfer in aerobic respiration is mimicked by mediator coupling of tyrosinase catalysis to an electro-chemical system. An enzyme-coupled oxygen electrode is created which is sensitive to selective poisoning. Biocatalytic reduction of oxygen is promoted by electrochemically supplying tyrosinase with electrons. Thus, ferrocyanide is generated at a cathode and mediates the enzymatic reduction of oxygen to water. An enzyme-dependent reductive current can be monitored which is inhibited by cyanide in a concentration-dependent manner. Oxygen depletion in the reaction layer can be minimized by addressing enzyme activity using a potential pulsing routine. Enzyme activity is electrochemically initiated and terminated and the sensor becomes capable of continuous monitoring. Cyanide poisoning of the biological component is reversible, and it can be reused after rinsing. The resulting sensor detects cyanide based on its biological activity rather than its physical or chemical properties.

Biosensors for environmental applications: Future development trends

“…Thus, OPH could be combined with an optical transducer to measure the absorbance of p-nitrophenol or with an amperometric transducer to monitor the oxidation or reduction current of this product [26]. With a different approach, the capability of various pesticides such as cyanide [27], diethyldithiocarbamates [28], and hydrazines [29] to inhibit the enzyme tyrosinase was also reported. Similarly, diazinon and dichlorvos were detected at limits around 5 µM and 75 µM, respectively, using a tyrosinase-based oxygen sensor [30].…”

Application of Biosensors in Biotechnology and Ecology

“…It is used for estimation of pollution in the course of wineproduction but in the same way can be discovered traces from sulfide ions in the food (93). For the determination of level of toxivity of the biological liquids water and industrial waste water are developed different variants of biosensors. One of them is with the Clark electrode and tirozine (94), which allowed to discover some traces of cyanide by the impulse inhibitor method. The other kind is a miniature ISFET -biosensor with peroxidase (95).…”

Electrically ‘wired’ tyrosinase enzyme inhibition electrode for the detection of respiratory poisons

“…Amelioration of this deterioration in signal is under investigation by addressing the enzyme activity using a potential pulsing strategy [3] thus minimizing oxygen depletion.…”

“…This study utilized a dual electrode strategy for the electrochemical generation of substrate (H202) at one electrode and detection of the solution mediator, ferrocene, at the second electrode. In an innovative approach Smit and Rechnitz [3] have replaced the respiratory enzyme CCO with tyrosinase, which is also inhibited by the respiratory poisons. They reported that the natural substrate for the tyrosinase enzyme could be replaced with an electrochemically regenerable solution redox species, ferrocyanide, that can act as an electron donor in the enzymatic reduction of oxygen, for the development of a 'reagentless' enzyme electrode for respiratory poisons which consumes only oxygen.…”