A Novel Approach to Detect 2,4,6-trinitrotoluene/2,4,6-trinitrophenol Based on Fluorescence Quenching via Charge Transfer of Silicon Quantum Dots

Abstract

Due to the significant detrimental effects of nitroaromatic explosive on the environment and human health, sensitive, rapid, on-site and simple detection methods for explosives are in high demand. A novel label-free silicon quantum dots (SiQDs)-based sensor is designed for ultrasensitive detection of 2,4,6-trinitrotoluene (TNT) and 2,4,6-trinitrophenol (TNP). In this work, amino-functionalized SiQDs are obtained through treating the SiQDs with (3-aminopropyl)triethoxysilane (APTES). The amine-coated SiQDs are not only water-stable but also highly luminescent. Based on the dramatic and selective fluorescence quenching of the amine-coated SiQDs due to charge transfer that resulting from the formation of stable Meisenheimer complexes between electron-deficient TNT/TNP and electron-rich primary amine on the surface of SiQDs, an instant and sensitive sensor is developed for the detection of TNT/TNP which is able to not only directly suppress the fluorescent emission intensity of SiQDs but also induce SiQDs aggregation to result in self-quenching of SiQDs. The results reveal that the developed sensor has high sensitivity for the detection of TNT/TNP. As indicated in experimental results, the fluorescence intensity is proportional to the concentration of TNT/TNP. Meanwhile, linear correlations are obtained respectively for the fluorescence signals to the logarithmic TNT and TNP concentration with 6 and 7 order of range and the detection limit of TNT and TNP is 50 pg/mL for TNT and 5 pg/mL for TNP. Further experiments demonstrate that this analytical method is not susceptible to pH and prevent interference from other nitroaromatics or cationic ions. This simple and cost-effective sensor can be used to detect ultra-trace TNT/TNP in groundwater or seawater. Additionally, this sensor strategy may provide a convenient, rapid, highly sensitive and selective assay platform for nitroaromatic explosive.

Highly sensitive detection of 2,4,6-trinitrophenol (TNP) based on lysozyme capped CdS quantum dots

“…Abundant amino groups exist on lysozyme and can effectively bind TNP via the formation of Meisenheimer complexes between the electron-rich amino groups of lysozyme and the electron-decient nitroaromatic rings of TNP. 15,16 TNP bound to the surface of lysozyme can lead to uorescence quenching through electron transfer from the conductive band of the CdS QDs to the lowest unoccupied molecular orbital of TNP. 17,18 The new generation of CdS QDs in situ can avoid some drawbacks of presynthesized QDs in relevant analytical systems by decreasing the background signal.…”