Fluorescent probe/hydrogel-based portable platform for ultrasensitive on-site detection of explosive particles containing nitrite

On-the-spot identification of solid or deposited explosive airborne particulates through luminescence techniques plays a vital role in homeland security, environmental analysis, and medicolegal diagnosis. However, integrating the rapid collection of solid explosive particles with fluorescent probe equipment and developing a direct and ultrasensitive detection technique for explosive particles on-site remain a formidable challenge in the fluorescence sensing field. In this study, we developed a portable detection platform based on a complex system using a combination of fluorescence probes/hydrogels and smartphone technology, which could not only quickly collect and capture explosive airborne particles but could also immediately synchronously realize ultrasensitive detection. The newly designed fluorescent probe 2-(5-chloro-1H-benzo [d] imidazol-2-yl) aniline (10-CBMA) exhibited superior recognition ability compared to two other probes, namely, BMA and 9,10-CBMA, for nitrite solution and solid conditions, with a low detection limit (8.558 × 10−8 M, solution), a quick detection time (2 mins, solid), and excellent specificity even in the presence of other interfering ions. In addition, by utilizing the robust photography capabilities of smartphones, nitrite particles could be quickly recognized on the spot. Overall, this portable platform based on fluorescence probes/hydrogels for ultrasensitive nitrite solid detection strategy provided in-depth insights into advancing explosive detection.