Applying a Surface-Sensitive Fluorescence Method to Fast on- Site Detection of Cocaine in Saliva

AbstractFast and sensitive detection of cocaine in saliva is realized utilizing a surface-sensitive fluorescence measurement platform. The platform is based on a polystyrene parabolic lens that enables the simultaneous application of total internal reflection excitation (TIR) and supercritical angle fluorescence detection (SAF), which results in extreme surface sensitivity in the measurements. The molecular recognition takes place in a scheme, where cocaine molecules to be detected generate a displacement of the labelled anti-cocaine antibodies from the cocaine-BSA-conjugate molecules immobilized on a surface. The results with untreated saliva spiked with cocaine demonstrate that by monitoring the dissociation process in real time, cocaine concentrations down to 1 ng/mL can be detected within 60s