Nahla Abdelshafi
Bundesanstalt für Materialforschung und –prüfung, Germany
Title: Immunosensor for drug monitoring using voltammetry
Biography
Biography: Nahla Abdelshafi
Abstract
Cocaine is a stimulant, addictive and illicit substance which can be detected in urine, saliva and even on banknotes. Immunoassay based on the strong and selective antibody-antigen interaction is considered an analytical technique with high potential. Electrochemical detection methods are increasingly used with immunoassays as they offer some advantages of being simple, cheap, and portable. Assay integration on microfluidic chip platforms offers additional advantages including small sample and reagent volumes and fast analysis time allowing for flow injection analyses with high levels of throughput and automation providing a sensor-type platform. An electrochemical immunosensor for cocaine screening, especially in roadside testing but also in epidemiological studies (e.g. drugs in wastewater, drugs on banknotes) was developed. The immunosensor is based on using magnetic beads as antibody carriers in a microfluidic platform. The calibration curve was plotted as 4-parameter logistic fit non-linear relationship between cocaine concentrations and the applied potential peak. The assay showed high sensitivity with a detection limit of 14 ng/L of cocaine. The effect of salts, acids and bases on the detection method was investigated, where the presence of ions affected the redox reaction and converted the system from quasi-reversible to reversible. A drug screening application (cocaine on banknotes) showed 100% contamination of the Euro banknotes in Germany with contamination ranging from 60 ng/note to 1.1 mg/note. The results demonstrated that an electrochemical microfluidic immunoassay could provide a fast, inexpensive, portable and suitable sensor platform in practical application.