Drug abuse is a major public problem in the workplace, traffic, and forensic issues, which requires a standardized test device to monitor on-site drug use. For field testing, the most important requirements are portability, sensitivity, non-invasiveness, and quick results. Motivated by this problem, a point of care (POC) test based on lateral flow assay (LFA) was developed for the detection of cocaine (COC) and methamphetamine (MET) in saliva which has been selected as the matrix for this study due to its rapid and non-invasive collection process. In the design strategy of an LFA test, the use of gold nanoparticles (AuNPs) with strong optical properties has been combined with the advantages of selecting aptamers under in vitro conditions, making it a highly specific and stable recognition probe for the detection of small molecules in saliva. The developed aptamer-based LFA in a competitive format, was able to detect COC and MET in synthetic saliva at concentrations as low as 5.0 ng/mL. After analytical performance studies, the test system also detected COC and MET in real patient samples, which was verified by chromatographic methods.
