In situ, real-time, colorimetric detection of γ-hydroxybutyric acid (GHB) using self-protection products coated with chemical receptor-embedded hydrogel.

Due to the increase in drug-facilitated sexual assault (DFSA) enabled by the illegal use of drugs, there have been constant demands for simple methods that can be used to protect oneself against crime in real life. γ-Hydroxybutyric acid (GHB), a central nervous system depressant, is one of the most dangerous drugs for use in DFSA because it is colorless and has slow physiological effects, which pose challenges for developing in situ, real-time GHB monitoring techniques. In this study, we developed a method for in situ colorimetric GHB detection using various self-protection products (SPPs) coated with 2-(3-bromo-4-hydroxystyryl)-3-ethylbenzothiazol-3-ium iodide (BHEI) as a chemical receptor embedded in hydrogels. Additionally, smartphone-based detection offers enhanced colorimetric sensitivity compared to that of the naked eye. The developed SPPs will help address drug-facilitated social problems.