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

Abstract

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.

Nanoconfinement of pyrene in mesostructured silica nanoparticles for trace detection of TNT in the aqueous phase

“…When TNT binds to pyrene through the π-π* interaction, emission of pyrene is quenched through photoinduced electron transfer (PET) from an excited pyrene molecule to TNT. 23 To investigate the TNT sensing performance of the pMSNs, we recorded fluorescence spectra of pMSN dispersion before and after the addition of TNT with concentrations ranging from 10 nM to 10 µM. Both monomer and excimer emission intensities of pyrene were quenched gradually with increasing TNT concentration (Fig.…”

“…It is well known that fluorescence of pyrene (a π-conjugated fluorophore with high quantum yield and long lifetime) is quenched by nitroaromatic explosives through photoinduced electron transfer (PET). 22,23 Particularly, excimer emission of pyrene, which is observed in the presence of π-π* stacking interaction between the excited and ground state pyrene molecules, is very sensitive towards nitroaromatics. Recently, we and others used pyrene excimer fluorescence for the detection of nitroaromatic molecules utilizing nanomaterials that contain chemically attached or more simply physically encapsulated pyrene molecules.…”

Fluorescent Nanofilms for Nitroaromatic Explosives Detection-Promises and Challenges

“…In China, based on fluorescent conjugated polymers, Cheng and co-workers also explored trace explosives detector (SIM series) which could detect explosives, such as nitro-aromatic explosives and plastic explosives at part per trillion (ppt) levels in 2007 [36]. Although significant advances have been achieved, the sensing performance of fluorescent conjugated polymers depends highly on the film thickness due to the slow diffusion of analyte vapors in the non-porous rigid conjugated polymer films [30,37]. And the synthesis process of conjugated polymers is complex [38].…”

“…Although significant advances have been achieved, the sensing performance of fluorescent conjugated polymers depends highly on the film thickness due to the slow diffusion of analyte vapors in the non-porous rigid conjugated polymer films [30,37]. And the synthesis process of conjugated polymers is complex [38].In this regard, electrospinning technology which is a simple and cost-effective approach to prepare nanofibrous films has been developed very rapidly in recent years [37]. Guangtao Li pioneered electrospun fibrous membranes for TNT detection, and the quenching efficiency was comparable to that of conjugated polymer-based TNT sensors [11].…”

“…In this regard, electrospinning technology which is a simple and cost-effective approach to prepare nanofibrous films has been developed very rapidly in recent years [37]. Guangtao Li pioneered electrospun fibrous membranes for TNT detection, and the quenching efficiency was comparable to that of conjugated polymer-based TNT sensors [11].…”