Rapid and Accurate On-Site Screening for a Broad Range of Synthetic Cathinones by Electronic Drug Analyzer Based on a Cross-Reactive Aptamer

As submitted by the proposer: Although synthetic cathinones (also known as 'bath salts') have emerged recently, the abuse of bath salts has become a threat to public health and safety due to their severe toxicity, widespread use and difficulty of regulation. The most prevalent drug field tests for seized substances include chemical testing and lateral-flow immunoassays. The testing reagents in chemical testing often react with non-target compounds in the samples to produce false positives. On the other hand, many bath salt derivatives do not react with one or more of the testing reagents due to side-chain substitutions, resulting in false negatives. Alternatively, the presence of drugs can be detected with immunoassays based on the specific binding between antibodies and drugs, allowing accurate identification of selected targets. However, these assays suffer from false negatives due to the fact that designer drugs are rapidly modified based on their core structure, and this minor structure modification can greatly impair binding with existing detection antibodies. Currently, bath salts cannot be effectively screened using traditional field test kits. We propose to develop a portable field-testing device, which uses a DNA-based affinity element - aptamer - to cross-reactively detect a broad range of synthetic cathinones in a paper strip assay format, with a user-friendly electronic digital readout of the screening results. There are two major innovative components of this project. First, we will use a Systematic Evolution of Ligands by Exponential enrichment technique with a structured library, a proposed selection strategy and a carefully-designed counter-selection procedure to isolate an aptamer that binds to the core structure of synthetic cathinones without responding to interferents found in street samples. Second, we will integrate this cross-reactive aptamer into a paper-based electrochemical aptamer-based (E-AB) sensor that is paired with a battery-powered potentiostat to develop a portable, user-friendly electronic drug (E-Drug) analyzer. This analyzer should be capable of performing accurate, rapid and single-step screening for bath salts in seized substances within 10 seconds, resulting a digital readout without interpreter bias. This analyzer should enable more efficient screening for all existing bath salts, reducing both the false positives and false negatives associated with chemical field tests and immunoassays, with the built-in capacity to effectively screen for newly-emerging derivatives that share the same core structure. Critically, the aptamer discovery and implementation workflow developed here should has the potential to revolutionize field tests of other classes of designer drugs in seized substances by permitting immediate and accurate feedback from presumptive testing. Note: This project contains a research and/or development component, as defined in applicable law. ca/ncf