Abstract
This proof-of-concept study proposed a novel sensing technique for a label-free and selective detection of 2,4,6-trinitrotoluene (TNT) from 10−12 to 10−4 molar. Amine-terminated nanoparticles were used as TNT bioreceptors to form Meisenheimer complexes. A colorimetric change from green to red was observed after TNT functionalization, which caused by the increased in the nanoparticles separation. AptamerX was subsequently attached to confirm the sensing selectivity from 2,4-dinitrotoluene control and baseline toluene. A combined effect of the peak wavelength shift of the reflected light normal to the film surface and the associated change of the peak width presents the merit function of this study.
Highlights
Sensing of trace explosives such as 2,4,6-trinitrotoluene (TNT) is a complex and challenging task due to the lack of inexpensive sensors with high selectivity and sensitivity [1], the lack of detectable signals, and wide selection of explosive compositions [2,3]
The colorimetric response examined in this work was focused on dried nanoparticle films, from which the reflected light was studied
We expect that the reflected light from the functionalized nanoparticles in liquid will behave differently, which may reveal more information regarding the interactions between them
Summary
Sensing of trace explosives such as 2,4,6-trinitrotoluene (TNT) is a complex and challenging task due to the lack of inexpensive sensors with high selectivity and sensitivity [1], the lack of detectable signals, and wide selection of explosive compositions [2,3]. Current sensing methods of nitro-based explosives are gas and liquid chromatography [14], mass spectrometry [15], ion-mobility spectroscopy [16], enzymatic assays [17], and electrochemical detection [18]. A simple and label-free alternative is to use optical detection in association with designed colorimetric arrays of charge-transfer acceptor/donor complexes made of colloidal mesoporous nanoparticles based on specific color responses via donor–acceptor interactions between TNT and primary amines [19,20], but how to detect TNT in a wide range of concentrations using such a method remains to be investigated
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