Electrospun fluorescent sensors for the selective detection of nitro explosive vapors and trace water

For the practical applicability of fluorescent sensors for explosives, it is significantly important to discriminate between nitro explosives and water-based interferents, due to the unavoidable need for detection in commonly humid fields or conditions. Herein, we made a detailed investigation on the sensing selectivity of highly sensitive fluorescent sensors of polystyrene/9-(pyren-1-yl)-9H-carbazole (PS/PyCz) nanofibers and polyethylene oxide/9-(pyren-1-yl)-9H-carbazole (PEO/PyCz) nanofibers fabricated via a facile low-cost electrospinning strategy. It was found that PEO/PyCz nanofibers exhibit a sensitive response to nitro explosive vapors, but they cannot resist interference from non-nitro substances encountered in daily-life, including water, perfume, orange juice, wine, etc. It was demonstrated that the excited PyCz molecules would lose energy due to enhanced molecular rotation in water-based PEO/PyCz nanofibers. Because of a favorable photo-induced electron transfer driving force between the PyCz fluorophore and nitro explosives, the fluorescence of the materials resulted in similar strong responses to the explosives. However, the PS/PyCz nanofibrous film can detect not only nitro explosive vapors with high sensitivity, but also exhibits high selectivity over the typical common water-based interferents due to its hydrophobicity. This work provides a new aspect for fluorescent sensor design and component control for the reliable identification of nitro explosives in practical application fields for controlling environmental pollution, combating terrorism and improving national security.