Selective Detection Of Trinitrotoluene Research Articles

Plasmonic Coupling of Au Nanoclusters on a Flexible MXene/Graphene Oxide Fiber for Ultrasensitive SERS Sensing.

High sensitivity, good signal repeatability, and facile fabrication of flexible surface enhanced Raman scattering (SERS) substrates are common pursuits of researchers for the detection of probe molecules in a complex environment. However, fragile adhesion between the noble-metal nanoparticles and substrate material, low selectivity, and complex fabrication process on a large scale limit SERS technology for wide-ranging applications. Herein, we propose a scalable and cost-effective strategy to a fabricate sensitive and mechanically stable flexible Ti3C2Tx MXene@graphene oxide/Au nanoclusters (MG/AuNCs) fiber SERS substrate from wet spinning and subsequent in situ reduction processes. The use of MG fiber provides good flexibility (114 MPa) and charge transfer enhancement (chemical mechanism, CM) for a SERS sensor and allows further in situ growth of AuNCs on its surface to build highly sensitive hot spots (electromagnetic mechanism, EM), promoting the durability and SERS performance of the substrate in complex environments. Therefore, the formed flexible MG/AuNCs-1 fiber exhibits a low detection limit of 1 × 10-11 M with a 2.01 × 109 enhancement factor (EFexp), signal repeatability (RSD = 9.80%), and time retention (remains 75% after 90 days of storage) for R6G molecules. Furthermore, the l-cysteine-modified MG/AuNCs-1 fiber realized the trace and selective detection of trinitrotoluene (TNT) molecules (0.1 μM) via Meisenheimer complex formation, even by sampling the TNT molecules at a fingerprint or sample bag. These findings fill the gap in the large-scale fabrication of high-performance 2D materials/precious-metal particle composite SERS substrates, with the expectation of pushing flexible SERS sensors toward wider applications.

Fluorescent Sensing Assay for Trinitrotoluene Using Fluorescein Isothiocyanate Conjugated Mesoporous MCM-41 Particles

In the present study, Trinitrotoluene (TNT) has been detected by the formation of Meisenheimer complex using Fluorescein isothiocyanate (FITC) dye loaded Mesoporous silica particles (MCM-41). FITC dye loaded mesoporous silica particles (MCM-41/FITC) have been synthesized using (3-Aminopropyl)trimethoxysilane, APTMS (λex = 490 nm and λem = 512 nm). TNT forms Meisenheimer complex with the amine group of APTMS present on MCM-41 particles. The loading of FITC in the pores of MCM-41 particles has been confirmed by different advanced characterization techniques. The average diameter of mesoporous MCM-41 particles was found about 130 nm. Pore volume is observed to decrease from 1.06 cm3/g to 0.49 cm3/g after FITC loading. The selective detection of TNT up to 0.1 ppb level makes MCM-41/FITC particles a potential sensing material for TNT detection.

Polyethylene imine capped copper nanoclusters- fluorescent and colorimetric onsite sensor for the trace level detection of TNT

Rapid, reliable, onsite approaches for the trace level detection of trinitrotoluene (TNT) is a pressing necessity for both homeland security and environmental protection. Selective detection of TNT from other nitroaromatics is still challenging as it possess similar chemical structure and properties with its analogues. In the present work, the water soluble polyethylene imine protected copper nanoclusters (PEI CuNC) were developed as fluorescent and colorimetric probe which can detect TNT selectively and sensitively both in aqueous and vapour form. The PEI CuNC with size less than 3nm was prepared via a simple one pot microwave method and exhibited bright blue emission at 480nm. The fluorescence of PEI CuNC can be remarkably quenched by TNT through the formation of amine-TNT Meisenheimer complex. Quenching was further facilitated by fluorescence resonance energy transfer (FRET) and inner filter effect (IFE). A good linearity was observed for the PEI CuNC based fluorescence detection of TNT with limit of detection 14 pM. Meanwhile the formation of Meisenheimer complex resulted in a significant colour change of the solution from pale green to red, which enables visual detection of TNT with detection limit down to 0.05nM. The fluorescence as well as colorimetric method displayed excellent selectivity and sensitivity over other interfering compounds and ions. Fluorescent paper strip sensor was developed to detect TNT in vapour phase as well as solution form. PEI CuNC coated paper strips were able to detect TNT vapours with in one minute with a limit of detection 10nM, providing a valuable platform for sensing TNT in public safety and security.

Highly sensitive and selective detection of trinitrotoluene using cysteine-capped gold nanoparticles

(A) A schematic representation of the formation of cysteine capped gold nanoparticles and their interaction at pH 5 and 9.3. (B) A schematic representation of the formation of a Meisenheimer complex between cysteine modified gold nanoparticles and TNT, and possible cross-linking between gold nanoparticles bound to the Meisenheimer complex with gold nanoparticle bound cysteine.

L-cysteine-capped CdTe QD-based sensor for simple and selective detection oftrinitrotoluene

Trinitrotoluene, usually known as TNT, is a kind of chemical explosive with hazardous andtoxic effects on the environment and human health. National and societal security concernshave dictated an increasing need for the analytical detection of TNT with rapidity, highsensitivity and low cost. This work demonstrates a novel method using L-cysteine-cappedCdTe quantum dots (QDs) to assay TNT, based on the formation of a Meisenheimercomplex between TNT and cysteine. The fluorescence (FL) of quantum dots quenchbecause electrons of the QDs transfer to the TNT molecules via the formation of aMeisenheimer complex. TNT can be detected with a low detection limit of 1.1 nM.Studies on the selectivity of this method show that only TNT can generate anintense signal response. The synthesized QDs are excellent nanomaterials for TNTdetection. In addition, TNT in soil samples is also analyzed by the proposed method.

Gold Nanoparticle Based Label-Free SERS Probe for Ultrasensitive and Selective Detection of Trinitrotoluene

TNT is one of the most commonly used nitro aromatic explosives used for landmine and military purpose. Due to the significant detrimental effects, contamination of soil and groundwater with TNT is the major concern. Driven by the need to detect trace amounts of TNT from environmental samples, this article demonstrates for the first time a highly selective and ultra sensitive, cysteine modified gold nanoparticle based label-free surface enhanced Raman spectroscopy (SERS) probe, for TNT recognition in 2 pico molar (pM) level in aqueous solution. Due to the formation of Meisenheimer complex between TNT and cysteine, gold nanoparticles undergo aggregation in the presence of TNT via electrostatic interaction between Meisenheimer complex bound gold nanoparticle and cysteine modified gold nanoparticle. As a result, it formed several hot spots and provided a significant enhancement of the Raman signal intensity by 9 orders of magnitude through electromagnetic field enhancements. A detailed mechanism for termendous SERS intensity change has been discussed. Our experimental results show that TNT can be detected quickly and accurately without any dye tagging in lower pM level with excellent discrimination against other nitro compounds and heavy metals.

Polymer-Oligopeptide Composite Coating for Selective Detection of Explosives in Water

The selective detection of a specific target molecule in a complex environment containing potential contaminants presents a significant challenge in chemical sensor development. Utilizing phage display techniques against trinitrotoluene (TNT) and dinitrotoluene (DNT) targets, peptide receptors have previously been identified with selective binding capabilities for these molecules. For practical applications, these receptors must be immobilized onto the surface of sensor platforms at high density while maintaining their ability to bind target molecules. In this paper, a polymeric matrix composed of poly(ethylene-co-glycidyl methacrylate) (PEGM) has been prepared. A high density of receptors was covalently linked through reaction of amino groups present in the receptor with epoxy groups present in the co-polymer. Using X-ray photoelectron spectroscopy (XPS) and gas-chromatography/mass spectroscopy (GC/MS), this attachment strategy is demonstrated to lead to stably bound receptors, which maintain their selective binding ability for TNT. The TNT receptor/PEGM conjugates retained 10-fold higher TNT binding ability in liquid compared to the lone PEGM surface and 3-fold higher TNT binding compared to non-specific receptor conjugates. In contrast, non-target DNT exposure yielded undetectable levels of binding. These results indicate that this polymeric construct is an effective means of facilitating selective target interaction both in an aqueous environment. Finally, real-time detection experiments were performed using a quartz crystal microbalance (QCM) as the sensing platform. Selective detection of TNT vs DNT was demonstrated using QCM crystals coated with PEGM/TNT receptor, highlighting that this receptor coating can be incorporated as a sensing element in a standard detection device for practical applications.