Investigation of rosmarinic acid as a mediator in NADH sensors and alcohol dehydrogenase-based biosensors

The main aim of this study is to investigate the effect of rosmarinic acid (RA), a natural antioxidant, as a mediator on NADH sensors and dehydrogenase based amperometric biosensors developed for ethanol determination. In the first part of the work, screen-printed carbon electrodes (SPCE) were modified with RA.Then these electrodes were characterized electrochemically using cyclic voltammetry. Their use as an NADH sensor was examined. Theparameters such as pH and working potential were optimized for NADH determination. In the second part of the work, a biosensor was developed,to be sensitive to ethanol, by adding alcohol dehydrogenase(ADH) enzyme to the structure of the RA modified SPCE.The electrochemical characterization and optimization studies for amount of coenzyme NAD+, pH and working potentialwere performed for the developed biosensor.Its analytical characterization was also performed. Within this scope, performance criteria such as storage and application stability as well as reproducibility of the biosensorwere determined. One of the most important effects of the antioxidant substance RA as a mediator in the structure of the NADH sensor and ADH-based biosensor is found to bethe lowering of the working potential in NADH and alcohol determinations. This effect helps eliminating interferences in NADH and alcohol analyses.