Novel surface design by stabilization of aptamer and antibody for illicit drug sensing systems: cocaine and methamphetamine sensors

Antibody- based and aptamer –based sensors are popular platforms in the detection of diagnostic protein markers, nucleic acids and drugs. Thus these system could be used for abused drugs.Therefore,we created a new platform for the detection of common abused drugs; methamphetamine (METH) and cocaine (COC). Firstly, a fluorescent-labeled polypeptide (EDOT-BTDA-Pala) was used as as a glassy carbon electrode (GCE) covering host to immobilize the METH- antibody.Prior to the analysis of METH, GCE/EDOT-BTDA-Pala/Antibody surface was characterized with electrochemical (cyclic voltammetry and electrochemical impedance spectroscopy). As for the analytical parameters of the system linearity and limit of detection (LOD) was found as 10 - 100 µg/mL with an equation of y = 0.0429x-0.2347, (R2=0.996) and 13.07 µg/mL, respectively.In addition, sample application using the synthetic urine, saliva and serum samples spiked with METH (10, 25, 50 µg/mL) carried out and LC-MS/MS system was used for the confirmation of the platform.For the dedection cocaine ; EDOT-BTDA-PPhe was used as conductive polymer host to immobilize the cocaine –antibody and aptamer. Prior to dedection of cocaine GCE/ EDOT-BTDA-PPhe /Antibody-Aptamer surface was characterized with electrochemical (cyclic voltammetry and electrochemical impedance spectroscopy). The designed aptamer based-biosensing system was applied for the detection of cocaine and its metabolite; benzoylecgonine (BE) which exhibited a linear correlation in the range from 0.5µM up to 25µM and 0.5 µM up to 50 µM for cocaine and BE, respectively. As for the antibody-based sening system ,for both analytes, linearity was obtained between 0.5-25 µM. Finally, the created systems was successfully used for the analysis of synthetic biological fluids. Keywords: Drug abuse; methamphetamine; cocaine;anibody-based biosensor;aptamer-based biosensor