Contents I. Introduction
Cocaine is one of the most commonly abused drugs and this has led to extensive investigative research efforts for its detection, due to the adverse health effects and related dangers associated with its illicit use [1], [2]. There are several major analytical methods available for the analysis of cocaine and its metabolites including gas chromatography mass spectrometry (GC/MS) [3], [4], high performance liquid chromatography (HPLC) [5], [6], thin layer chromatography [7], voltammetry [8], radioimmunoassay [9] and enzyme-linked immunosorbent assay (ELISA) [10]. These traditional methods, despite having achieved very good results, are generally expensive, time consuming and cumbersome for real-time measurements outside the laboratory, some of which also require sample clean-up and derivatization of cocaine prior to analysis. Biosensors, which rely on the specificities of the binding sites of receptors, enzymes, antibodies or DNA as biological sensing elements, have been considered as alternative analytical devices due to their specificity, portability, speed and low cost [11]. Biosensors for cocaine based on monoclonal antibodies [12], [13] and especially aptamers [14]–[18] have been developed in recent years. However, these sensors suffer from certain limitations in light of their potential practical applications in the field due to the fragile and unstable nature of the biological recognition elements. Therefore, the development of stable, compact and portable sensing systems which are capable of real time detection of the target drug remains a compelling goal which is addressed in this work.
