title: Colorimetric-based detection of TNT explosives using functionalized silica nanoparticles.
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.
authors.affiliation: Electrical Engineering Division, Department of Engineering, University of Cambridge, 9 JJ Thomson Avenue, Cambridge CB3 0FA, UK. ni245@cam.ac.uk.|Institute of Nano Electronic Engineering (INEE), Universiti Malaysia Perlis (UniMAP), Lot 106, 108 & 110, Tingkat 1, Block A, Taman Pertiwi Indah, Jalan Kangar-Alor Setar, Seriab 01000 Kangar, Perlis, Malaysia. ni245@cam.ac.uk.
authors.forename: Noorhayati
authors.initials: N
authors.lastname: Idros
authors.affiliation: Electrical Engineering Division, Department of Engineering, University of Cambridge, 9 JJ Thomson Avenue, Cambridge CB3 0FA, UK. MHo2@slb.com.|Schlumberger Cambridge Research, High Cross, Madingley Road, Cambridge CB3 0EL, UK. MHo2@slb.com.
authors.forename: Man Yi
authors.initials: MY
authors.lastname: Ho
authors.affiliation: Electrical Engineering Division, Department of Engineering, University of Cambridge, 9 JJ Thomson Avenue, Cambridge CB3 0FA, UK. mp380@cam.ac.uk.
authors.forename: Mike
authors.initials: M
authors.lastname: Pivnenko
authors.affiliation: Electrical Engineering Division, Department of Engineering, University of Cambridge, 9 JJ Thomson Avenue, Cambridge CB3 0FA, UK. qmm20@cam.ac.uk.
authors.forename: Malik M
authors.initials: MM
authors.lastname: Qasim
authors.affiliation: State Key Laboratory of Bioelectronics, School of Biological Science and Medical Engineering, Southeast University, Sipailou 2, Nanjing 210096, China. huaxu@seu.edu.cn.
authors.forename: Hua
authors.initials: H
authors.lastname: Xu
authors.affiliation: State Key Laboratory of Bioelectronics, School of Biological Science and Medical Engineering, Southeast University, Sipailou 2, Nanjing 210096, China. gu@seu.edu.cn.
authors.forename: Zhongze
authors.initials: Z
authors.lastname: Gu
authors.affiliation: Electrical Engineering Division, Department of Engineering, University of Cambridge, 9 JJ Thomson Avenue, Cambridge CB3 0FA, UK. dpc31@cam.ac.uk.
authors.forename: Daping
authors.initials: D
authors.lastname: Chu
keywords: aptamer; colorimetric; explosives; functionalized nanoparticles; label-free; self-assembly film