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 covalent immobilization of aptamer-functionalized AgNPs on the MWCNTs/IL/Chit nanocomposite as the sensing interface which improves the conductivity and performance characteristics of the aptasensor and enhances the loading amount of the aptamer DNA sequence. The 5′-NH2-3′-AgNPs-terminated aptamer is covalently attached to a MWCNTs/IL/Chit nanocomposite modified glassy carbon electrode (GCE) by terephthalate as the linker agent via amide coupling. In this study, riboflavin (RF) has been used for the first time as the redox probe in the development of the electrochemical aptasensor for the diagnosis of cocaine. AgNPs lead to the acceleration of the electron transfer kinetics related to the reduction of RF. Upon incubation of cocaine with the aptamer, the differential pulse voltammetric (DPV) signal of the RF decreases due to the hindered electron transfer reaction on the electrode surface. The peak current of the RF linearly decreases with increased concentration of cocaine from 2 nM to 2.5 µM with a detection limit (S/N= 3) of 150 pM. By using certain analgesic drugs as the interfering agents, the excellent specificity of this sensing system for cocaine measurement is also demonstrated. Finally, the proposed aptasensor has successfully been used to detect cocaine in human serum samples. The aptasensor presented here shows favorable electrochemical features and may hold great promise for the development of other electrochemical aptasensors for target detection.
کلید واژگان :Electrochemical aptasensor Cocaine Silver nanoparticle Riboflavin Nanocomposite
ارزش ریالی : 600000 ریال
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