Electrochemical cocaine biosensor

Cocaine is a highly addictive substance developing a strong tolerance due to stimulate directly affects the brain. Therefore, nowadays, fast and sensitive analysis of cocaine which plays important role for law enforcement and medicine diagnostic. The aim of the present study was to develop a novel electrochemical biosensor to detect cocaine alternatively compared to the traditional methods. In this context first step, bio-recognition surface as a new platform was designed on aptamer-based sensing. Initially, polythiophene bearing polyalanine homopeptide side chains (PT-Pala) was electrochemically coated onto the surface of an electrode and then cocaine aptamer was attached to the polymer via covalent conjugation chemistry. The stepwise modification of the surface was confirmed by electrochemical characterization. The designed biosensing system was applied for the detection of cocaine and its metabolite, (BE), which exhibited a linear correlation in the range from 2.5 up to 10 nM and 0.5 up to 50 μM for cocaine and BE, respectively. Moreover, the sensor showed high sensitivity and could easily detect cocaine as low as 1.5 nM for BE. Importantly, the BE was successfully demonstrated in sythentic biological fluids where it showed a potential of the practical application. In conclusion, the effective development of a particular electrochemical techniques was provided analysis of cocaine and its metabolite which have high specifity and sensitivity. It is a fact that this novel aptamer-based biosensing system may support further studies about an evaluable for law enforcement and clinical medicine diagnostic due to a benefical combination of the selective platform with electroanalytical techonolgy. Keyword: Cocaine, benzolyecgonine, cocaine aptamer, bioaffinity interaction, electrochemical biosensors, conjugation with biomolecules.