Structure-switching aptamers and sensors for detection of synthetic cathinones – IP 1849

Syntheticcathinones (also known as bath salts) are designer drugs sharing a similar corestructure with amphetamines and 3, 4-methylenedioxy-methamphetamine (MDMA). Theyare highly addictive central nervous system stimulants, and are associated withmany negative health consequences, including even death. Although these drugshave emerged only recently, abuse of bath salts has become a threat to publichealth and safety due to their severe toxicity, increasingly broadavailability, and difficulty of regulation. More importantly, there iscurrently no reliable presumptive test for any synthetic cathinone. Chemicalspot tests used to detect conventional drugs such as cocaine, methamphetamine, andopioids show no cross-reactivity to synthetic cathinones. FIU inventors have developedcross-reactive aptamers with structure-switching functionality and sensors forthe detection of synthetic cathinones. The generation of a structure-switchingcross-reactive aptamer entails digesting the cross-reactive aptamer with anexonuclease mixture, such as exonuclease III (Exo Ill) and exonuclease I (ExoI). The resulting digestion product has structure-switching functionality withsimilar or equal affinity as its parent cross-reactive aptamer and can bedirectly employed in folding-based aptamer sensors. The structure-switchingcross-reactive aptamers have been used in two different type of assays. One isa label free dye displacement assay where the presence of synthetic cathinonesis reported via a sensitive colorimetric signal for naked-eye detection. This colorimetricassay has excellent specificity because the aptamer does not cross-react tonon-synthetic cathinone interferents, can detect nanomolar synthetic cathinoneconcentrations even in urine and saliva in a label-free manner via instrumentalmeans, and can also achieve instantaneous detection of as low as 6.3 μM withthe naked-eye when the dye is used at a micromolar concentration. The second assayconsist of incorporating the structure-switching cross-reactive aptamers intoan electrochemical aptamer-based (E-AB) sensor, which comprises an electrode, andthe detection of the synthetic cathinone(s) is done by measuring an increase incurrent generated upon binding of the synthetic cathinone(s) to the sensor. E-ABsensors are an ideal choice for the detection of seized substances, becausethey are insensitive to sample matrix effects, have rapid response times(seconds-scale), can perform detection with minimal sample preparationrequirements, and can be easily miniaturized to detect low-volume samples(micro liters), thus allowing for analysis of trace amounts of substances. Anne Laure Schmitt Olivier aschmitt@fiu.edu 305-348-5948