Surfactants directly participate in the molecular recognition for visual and sensitive detection of fentanyl

Surfactants that are organized self-assembly to form micelles have been widely utilized for detection of several analytes. However, the surfactants only provide a hydrophobic space, which does not involve the molecular recognition process. Here, we report a surfactant-involved colorimetric assay for visual and sensitive detection of fentanyl (FTN), a third-generation new psychoactive substance. It is found that sodium dodecyl sulfate (SDS) simultaneously enhance the halogen-bonding interaction between Rose Bengal (RB) as the probe and FTN as well as stabilize the RB-FTN complex. This molecular recognition induces the intermolecular charge transfer, generating a significant redshift in the absorption band of RB and accompanying a distinct color change from red to purple. This assay possesses an ultrahigh response speed (within 1 min), and the limit of detection is calculated to be as low as 0.1 mg.L-1. It also shows good selectivity and application potential. The recovery rates of real samples are between 92.5% and 110%, suggesting that it is suitable for rapid and accurate analysis of food samples such as mineral water, orange juice and cocktail. The current strategy can be further exploited in surfactant enhanced detection applications for other substances.