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Colorimetric-based detection of TNT explosives using functionalized silica nanoparticles.

Idros N, Ho MY, Pivnenko M, Qasim MM, Xu H, Gu Z, Chu D - Sensors (Basel) (2015)

Bottom Line: The shift in the peak wavelength of the reflected light normal to the film surface and the associated change of the peak width were measured, and a merit function taking into account their combined effect was proposed for the detection of TNT concentrations from 10-12 to 10-4 molar.The selectivity of our sensing approach is confirmed by using TNT-bound nanoparticles incubated in AptamerX, with 2,4-dinitrotoluene (DNT) and toluene used as control and baseline, respectively.Our results show the repeatable systematic color change with the TNT concentration and the possibility to develop a robust, easy-to-use, and low-cost TNT detection method for performing a sensitive, reliable, and semi-quantitative detection in a wide detection range.

View Article: PubMed Central - PubMed

Affiliation: Electrical Engineering Division, Department of Engineering, University of Cambridge, 9 JJ Thomson Avenue, Cambridge CB3 0FA, UK. ni245@cam.ac.uk.

ABSTRACT
This proof-of-concept study proposes a novel sensing mechanism for selective and label-free detection of 2,4,6-trinitrotoluene (TNT). It is realized by surface chemistry functionalization of silica nanoparticles (NPs) with 3-aminopropyl-triethoxysilane (APTES). The primary amine anchored to the surface of the silica nanoparticles (SiO2-NH2) acts as a capturing probe for TNT target binding to form Meisenheimer amine-TNT complexes. A colorimetric change of the self-assembled (SAM) NP samples from the initial green of a SiO2-NH2 nanoparticle film towards red was observed after successful attachment of TNT, which was confirmed as a result of the increased separation between the nanoparticles. The shift in the peak wavelength of the reflected light normal to the film surface and the associated change of the peak width were measured, and a merit function taking into account their combined effect was proposed for the detection of TNT concentrations from 10-12 to 10-4 molar. The selectivity of our sensing approach is confirmed by using TNT-bound nanoparticles incubated in AptamerX, with 2,4-dinitrotoluene (DNT) and toluene used as control and baseline, respectively. Our results show the repeatable systematic color change with the TNT concentration and the possibility to develop a robust, easy-to-use, and low-cost TNT detection method for performing a sensitive, reliable, and semi-quantitative detection in a wide detection range.

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The Meisenheimer amine–TNT interaction demonstrates: (a) reaction between the amine group and TNT molecule and (b) a gradual change in color to the dark red of a TNT anion as the explosive concentration increases.
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sensors-15-12891-f002: The Meisenheimer amine–TNT interaction demonstrates: (a) reaction between the amine group and TNT molecule and (b) a gradual change in color to the dark red of a TNT anion as the explosive concentration increases.

Mentions: We first examined the interaction between TNT and amine groups by taking 8 μL of TNT at different concentrations and mixing with 8 μL of APTES, which also has a primary amine head group. A gradual change to a dark red color is observed in Figure 2 as the concentration of TNT increases. This is caused by the red-colored TNT anion [37,43]. The detection range by the naked eye is limited to 100 µM. On the other hand, using a high-resolution optical instrument, it is possible to detect a much lower range, as we show later in the paper.


Colorimetric-based detection of TNT explosives using functionalized silica nanoparticles.

Idros N, Ho MY, Pivnenko M, Qasim MM, Xu H, Gu Z, Chu D - Sensors (Basel) (2015)

The Meisenheimer amine–TNT interaction demonstrates: (a) reaction between the amine group and TNT molecule and (b) a gradual change in color to the dark red of a TNT anion as the explosive concentration increases.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4507664&req=5

sensors-15-12891-f002: The Meisenheimer amine–TNT interaction demonstrates: (a) reaction between the amine group and TNT molecule and (b) a gradual change in color to the dark red of a TNT anion as the explosive concentration increases.
Mentions: We first examined the interaction between TNT and amine groups by taking 8 μL of TNT at different concentrations and mixing with 8 μL of APTES, which also has a primary amine head group. A gradual change to a dark red color is observed in Figure 2 as the concentration of TNT increases. This is caused by the red-colored TNT anion [37,43]. The detection range by the naked eye is limited to 100 µM. On the other hand, using a high-resolution optical instrument, it is possible to detect a much lower range, as we show later in the paper.

Bottom Line: The shift in the peak wavelength of the reflected light normal to the film surface and the associated change of the peak width were measured, and a merit function taking into account their combined effect was proposed for the detection of TNT concentrations from 10-12 to 10-4 molar.The selectivity of our sensing approach is confirmed by using TNT-bound nanoparticles incubated in AptamerX, with 2,4-dinitrotoluene (DNT) and toluene used as control and baseline, respectively.Our results show the repeatable systematic color change with the TNT concentration and the possibility to develop a robust, easy-to-use, and low-cost TNT detection method for performing a sensitive, reliable, and semi-quantitative detection in a wide detection range.

View Article: PubMed Central - PubMed

Affiliation: Electrical Engineering Division, Department of Engineering, University of Cambridge, 9 JJ Thomson Avenue, Cambridge CB3 0FA, UK. ni245@cam.ac.uk.

ABSTRACT
This proof-of-concept study proposes a novel sensing mechanism for selective and label-free detection of 2,4,6-trinitrotoluene (TNT). It is realized by surface chemistry functionalization of silica nanoparticles (NPs) with 3-aminopropyl-triethoxysilane (APTES). The primary amine anchored to the surface of the silica nanoparticles (SiO2-NH2) acts as a capturing probe for TNT target binding to form Meisenheimer amine-TNT complexes. A colorimetric change of the self-assembled (SAM) NP samples from the initial green of a SiO2-NH2 nanoparticle film towards red was observed after successful attachment of TNT, which was confirmed as a result of the increased separation between the nanoparticles. The shift in the peak wavelength of the reflected light normal to the film surface and the associated change of the peak width were measured, and a merit function taking into account their combined effect was proposed for the detection of TNT concentrations from 10-12 to 10-4 molar. The selectivity of our sensing approach is confirmed by using TNT-bound nanoparticles incubated in AptamerX, with 2,4-dinitrotoluene (DNT) and toluene used as control and baseline, respectively. Our results show the repeatable systematic color change with the TNT concentration and the possibility to develop a robust, easy-to-use, and low-cost TNT detection method for performing a sensitive, reliable, and semi-quantitative detection in a wide detection range.

No MeSH data available.


Related in: MedlinePlus