Recyclable fluorescent paper sensor for visual detection of nitroaromatic explosives

Development of rapid, sensitive, and visual detection of nitroaromatic explosives is of great importance for homeland security and human safety. Herein, three novel fluorescent nanoporous polymers (FNPs), HPP-1-HPP-3, were first prepared by Heck reactions of octavinylsilsesquioxane with ethene derivatives containing bis-, tri-, or tetrakis- bromophenyl groups. Based on highly sensitive detection of explosives, including p-nitrotoluene (NT), 2,4-dinitrotoluene (DNT), 2,4,6-trinitrotoluene (TNT), 4-nitrophenol (NP), 2,4-dinitrophenol (DNP) and picric acid (PA), and high selectivity for detecting TNT and PA, by HPP-2 dispersion in ethanol, a fluorescent paper sensor was developed by a new fabrication process, i.e., vacuum filtrating of HPP-2 dispersion in ethanol, followed by washing and natural drying. The resultant paper sensor was found to be sensitive to explosives in the solution, solid and vapor phase with a rapid response time of < 10 s by visually observing the fluorescence quenching phenomenon. Moreover, this paper sensor is recyclable with desirable fluorescence resuming ratio, which is higher than 75% after 10 times recycle detection. This developed paper sensor is promisingly applied for rapid, on-site and visual sensing of explosive residuals. The remarkable fluorescence and reusability of this sensor could be expanded to other fluorescence detection of residuals.