A novel, simple and selective aptasensor for ultrasensitive detection of the addictive drug, cocaine,is developed using the electrochemical transduction method. The aptasensor is constructed by cova-lent immobilization of aptamer-functionalized AgNPs on the MWCNTs/IL/Chit nanocomposite as thesensing interface which improves the conductivity and performance characteristics of the aptasensorand enhances the loading amount of the aptamer DNA sequence. In this study, riboflavin (RF) has beenused for the first time as the redox probe in the development of the electrochemical aptasensor for thediagnosis of cocaine. AgNPs lead to the acceleration of the electron transfer kinetics related to the reduc-tion of RF. The differential pulse voltammetric (DPV) signal of the RF linearly decreases with increasedconcentration of cocaine from 2 nM to 2.5 M with a detection limit (S/N = 3) of 150 pM. By using certainanalgesic drugs as the interfering agents, the excellent specificity of this sensing system for cocaine mea-surement is also demonstrated. Finally, the proposed aptasensor has successfully been used to detectcocaine in human serum samples
