Efficiency electrochemical transduction

Electrochemical sensors operate efficiently if (1) a suitable biological or chemical recognition element is selected, (2) immobilized onto an electrode surface or in a membrane and (3) an appropriate electroanalytical transduction scheme is applied. 

Mechanistic aspects of the action of tyrosinase and the usual transduction schemes have been summarized on several occasions [166,170-173]. In short, this copper enzyme possesses two activities, mono- and di-phenolase. Due to the predominant presence of the mono phenolase inactive form (met-form), the enzyme is inherently inefficient for the catalysis of these monophenol derivatives. However, in the presence of a diphenol, the catalytic cycle is activated to produce quinones and the scheme results in an efficient biorecognition cascade. This activation is achieved more efficiently when combined with electrochemical detection through the reduction of the produced quinones [166], as illustrated in Fig. 10.5. Consequently, a change in the rate-hmiting step can be observed through kinetic to diffusion controlled sensors with a concomitant increase in stability and sensitivity, as depicted in Fig. 10.6. 

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