A novel paper-based chromogenic chemosensor for the rapid detection of benzodiazepines in beverages

Drug-facilitated sexual assaults represent a critical concern, frequently involving the surreptitious administration of benzodiazepines in beverages. Due to the limitations of traditional instrumental methods for on-site screening, there is a demand for rapid, low-cost, and reliable detection tools. Herein, we report a novel chromogenic chemosensor based on a meso -2,4-dinitrophenyl BODIPY derivative tailored for the specific detection of benzodiazepines. In an alkaline medium, the probe undergoes a reversible dissociation that shifts its color from pale pink to dark yellow. The subsequent addition of a benzodiazepine triggers a distinct naked-eye color transition to purple, achieving a limit of detection of 1.72 μM in solution for diazepam. This probe exhibits very good selectivity, showing no interference from common beverage components or other psychoactive substances used in drug-facilitated sexual assaults such as ketamine, scopolamine, or synthetic cathinones. To facilitate practical in situ application, a user-friendly solid-phase device was developed using cellulosic paper which enables the rapid colorimetric identification of benzodiazepines in real alcoholic and soft drinks. When coupled with smartphone-based image analysis, the device provides a limit of detection of 0.2 mM, which falls within the concentration range in adulterated beverages. These results demonstrate the potential of the proposed system as a sensitive, robust, and accessible tool for the prevention and on-site screening of chemical submission.