Molecularly Imprinted Silver Nanocomposites for Explosive Taggant Sensing

Abstract

Sensing explosive taggants such as 3-nitrotoluene (3-NT) and 2,3-dimethyl-2,3-dinitrobutane has become a strategic priority in homeland security. This work reports the synthesis of a solid-state plasmonic sensor based on a nanocomposite of Ag nanoparticles (NPs) embedded in a molecularly imprinted polymer (MIP) for selective detection of 3-NT, an explosive taggant for 2,4,6-trinitrotoluene. In our approach, the in situ synthesis of Ag NPs and the molecular imprinting with 3-NT as a template take place simultaneously inside the polyethyleneimine (PEI) thin film during the baking step after spin coating. The MIP sensor fabrication is done by a low-cost, fast, and scalable one-step procedure. We demonstrate the chemosensing capabilities of Ag-PEI MIP nanocomposites to 3-NT using the localized surface plasmon resonance band intensity decay as a sensing parameter. The molecular imprinting approach results in an enhancement of specific sensor response to 3-NT, with a limit of detection of 54.8 ng for 3-NT and a sensitivity of 24.0% ± 3.0%. We tested the MIP sensor specificity by comparing the sensor response to several NO2-containing molecules. The Ag-PEI MIP sensor demonstrated a robust, specific molecular recognition toward 3-NT. Because the MIP nanocomposite sensor is easy to prepare, easy to use, and inexpensive, these plasmonic sensors can be easily implemented with portable reading platforms into remote explosive detection and bomb disposal robots.

Molecularly imprinted nanocomposites of CsPbBr3 nanocrystals: an approach towards fast and selective gas sensing of explosive taggants

“…The mechanism of the PL quenching when analyte molecules interact with the CsPbBr 3 NC surface could be attributed due to an electronic energy transfer from the sensor (electron donor) to the 3-NT (electron acceptor) because the nitro group has a strong electron-withdrawing ability that makes the aromatic ring very electron-poor relative to benzene. 18,38,43,47…”

“…However, Ag-PEI 3-NT MIP sensors present a slow response time, and, in consequence, their application would be limited to some specific fields, such as sentinels in cargo ship containers. 18 Alternatively, fluorescence-based sensors for detecting explosives and taggants offer benefits such as short response time, low limit of detection (LOD) and high selectivity. 19 The sensing mechanism is predominantly based on fluorescence quenching when the analyte molecules interact with the fluorophores.…”

Highly-selective and sensitive plasmon-enhanced fluorescence sensor of aflatoxins

“…Gold and silver nanoparticles can be formed during the in situ synthesis in the structure of a number of polymers, e.g., poly(ethyleneimine), poly(hydroxyethyl methacrylate), poly(vinylpyrrolidone), novolak, poly(4-vinylphenol), poly(4-vinylphenol)-co-(methyl methacrylate), poly(styrene-co-allyl alcohol), 36,37 and MIPs. 38,39 The size and shape of the described nanoparticles as well as the distance between them, which are the important parameters determining their ability to enhance fluorescence intensity, can be controlled. 36,37 This paper introduces the novel nanostructured composite polymeric films with embedded in situ-synthesized Ag nanoparticles and a portable sensor device prototype for the PEFbased MIP-assisted detection of aflatoxins.…”

Luminescent CdSe Quantum Dot Arrays for Rapid Sensing of Explosive Taggants

“…Although the chemosensor exhibited a low limit of detection (LOD) and high selectivity, the response time of the sensing platform was too slow. Consequently, their application would be limited to specific fields, such as sentinels in cargo ship containers . The other gas sensor system consisted of two fluorescent molecularly imprinted nanocomposites based on CsPbBr 3 nanocrystals embedded in polycaprolactone (PCL) as a host matrix using 3-NT and nitromethane (NM) as template molecules for sensing and quantifying trace amounts of 3-NT.…”

“…Consequently, their application would be limited to specific fields, such as sentinels in cargo ship containers. 19 The other gas sensor system consisted of two fluorescent molecularly imprinted nanocomposites based on CsPbBr 3 nanocrystals embedded in polycaprolactone (PCL) as a host matrix using 3-NT and nitromethane (NM) as template molecules for sensing and quantifying trace amounts of 3-NT. These sensors combined the optical properties of the CsPbBr 3 nanocrystals and the high selectivity provided by the MIP to show a strong and very fast response after exposure with a low LOD.…”