Findings and methodology are reported for a project that developed a strategy for creating an effective presumptive screening assay that can perform rapid, sensitive, and accurate on-site detection of the entire synthetic cathinone (SC) family.
This presumptive test is needed, because SCs are highly addictive central nervous system stimulants that have many adverse health consequences, including death. The screening assay developed uses a DNA-based affinity element - aptamer - to detect cross-reactively a broad range of SC drugs in a colorimetric and electrochemical format. The project used systematic evolution of ligands by exponential enrichment (AELEX), a parallel-and-serial selection strategy, along with a designed counter-SELEX regimen to isolate a single class-specific aptamer that binds to the SC family. This process is expected to yield the first cross-reactive aptamer capable of recognizing virtually any SC, based on its related core structure, such that small chemical modifications should not significantly affect the aptamer's binding affinity. The project then integrated the resulting cross-reactive aptamer into both a colorimetric assay and an electrochemical aptamer-based (E-AB) sensor for naked-eye and digital detection of SCs, respectively. The interference-free performance of the E-AB sensor in various sample mixtures was confirmed. Both the colorimetric assay and E-AB sensor are rapid (seconds-scale), sensitive, specific, inexpensive, and user-friendly; this makes them useful for on-site presumptive testing of SCs. These methods should solve the problems of low sensitivity, poor selectivity, and limited cross-reactivity inherent with the commonly-used chemical spot test and immunoassays that typically produce false negative and false positive results in drug screening. 5 figures, 14 references, and a listing of project-related publications
Report (Grant Sponsored)
Date Published: January 1, 2019