Novel Signal-Amplifying Fluorescent Nanofibers for Naked-Eye-Based Ultrasensitive Detection of Buried Explosives and Explosive Vapors

A novel electrospun fluorescent nanofiberous membrane with a function like molecular wires was developed via electrospinning for the detection of ultra-trace nitro explosive vapors and buried explosives by naked eye under UV excitation. The high binding affinity between the electron-deficient nitro explosives and the sensing film results in a rapid, dramatic quenching in its fluorescence emission. A wide spectrum of nitro explosives, in particular, TNT, Tetryl, RDX, PETN and HMX could be visually detected at their sub-equilibrium vapors (less than 10 ppb, 74 ppt, 5 ppt, 7 ppt and 0.1 ppt, respectively) released from 1 ng explosives residues. Such outstanding sensing performance could be attributed to the proposed sandwich-like conformation between pyrene and phenyl pendants of PS which may allow efficient long-range energy migration similar to molecular wire, thus achieving amplified fluorescence quenching. Its application for the detection of buried explosives in soil by naked eye was also demonstrated, indicating its potential application for landmine mapping. To the best of our knowledge, this is the first report about the detection of buried explosives without the use of any advanced analytical instrumentation.