Electrochemical determination of cocaine using screen-printed cytochrome P450 2B4 based biosensors

This paper describes the development of screen-printed cytochrome P450 2B4 based biosensors, from the fabrication of the device using a single screen-printing technology to its characterization and application in the determination of cocaine street samples. Voltammetric measurements were first performed in order to study the electrochemical behavior of the enzyme trapped in the structure of the working electrode, as well as its interaction with one of its substrates, cocaine. Then, chronoamperometric measurements were carried out for the characterization of the biosensors. Calibration curves under optimum conditions of the experimental variables have been used for establishing the reproducibility (5.91%, n=5), the repeatability (10.45%, n=3) and the capability of detection (0.2 mM, α=β=0.05) of the described method in the calibration range from 0.2 to 1.2 mM. Finally, the performance of the developed biosensors has been successfully probed by the analysis of the purity of cocaine street samples.