Multifunctional Flexible SERS Sensor on a Fixate Gel Pad: Capturing, Derivation, and Selective Picogram Indirect Detection of Explosive 2,2′,4,4′,6,6′-Hexanitrostilbene

Abstract

2,2′,4,4′,6,6′-Hexanitrostilbene (HNS) is an explosive with better explosion performance than the well-known 2,4,6trinitrotoluene (TNT). Surprisingly, unlike other nitroaromatic explosives, there are limited reports regarding the detection of the HNS, let alone sensing reports on surface residues. In this work, a multifunctional flexible SERS sensor was proposed for the indirect detection of HNS based on the transparent fixate gel pads. The sticky and flexible gel pad can effectively collect any HNS surface residues. The inherent amine groups within the gel pad of which the main ingredient is polyurethane can react with HNS to form the orange Meisenheimer-alike complex. The modification of Ag NPs with halide ions was screened for the best SERS performance. KImodified-citrate-reduced Ag NPs showed selective but enormous SERS enhancement for the HNS derivative. The detection of HNS in the solution phase was explored, and a linear range of 0.01−25 ppm was achieved. The lowest detectable amount (LDA) of HNS was found to be 50 pg, making it one of the most sensitive methods in literature. It was successfully utilized for the HNS residues sensing on fingerprints and bags with LDAs of 5 and 200 ng, respectively. In addition, other explosives including TATB, LLM-105, RDX, HMX, FOX-7, and TNT were also examined to assess the selectivity of the fixate. It was found that the fixate showed excellent selectivity for HNS.

Towards practical and sustainable SERS: a review of recent developments in the construction of multifunctional enhancing substrates

“…[95][96][97] For example, Fan, et al demonstrated a flexible SERS sensor for rapid and in-field detection of the surface residues of a commonly used explosive, 2,2',4,4',6,6'hexanitrostilbene (HNS). 98 More specifically, the authors showed that commercially available sticky and flexible gel pads composed mainly of polyurethane could be used to extract HNS from complex sample surfaces through the formation of Meisenheimer-alike complexes between HNS and the amine moieties on the surface of the gel substrate which are visually identifiable as orange taints. Depositing aggregated citratereduced Ag nanoparticles directly onto the surface of the orange taints generated intense SERS signals of the analytesubstrate complexes which allowed indirect detection of HNS to be achieved.…”

Highly sensitive SERS detection of residual nitrofurantoin and 1‐amino‐hydantoin in aquatic products and feeds

“…According to a previous report, [ 13 ] the concentration of halide ions could also affect the SERS signal of the analyte. Hence, the concentration of Br − was then optimized.…”

“…Silver nitrate was reduced with sodium citrate to obtain Ag NPs according to our previous reports. [ 13,24 ]…”

“…However, there are limited reports concerning NFT detection and none about AHD by using surface‐enhanced Raman spectroscopy (SERS) method [ 11,12 ] that is a fingerprint spectral analysis method. [ 13–21 ] For example, Wu et al [ 11 ] used raspberry‐like nanogold to detect nitrofurazone and NFT in the extract of duck meat with the limit of detection (LOD) of 50 μg/L. Zhang et al [ 12 ] detected NFT with a LOD of 14 μg/L.…”

Topology Reliable LCST‐Type Behavior of ABA Triblock Polymer and Influence on Water Condensation and Crystallization

“…Smart hydrogels have been much concerned due to the stimulus responsive behaviors to the environmental triggers. [ 1–4 ] In order to develop their potential applications in various fields, such as wearable electronic devices, [ 5–8 ] flexible sensors, [ 9–13 ] biological drug‐carrying, [ 14–18 ] and storage cells, [ 19–21 ] it is very significant to adjust their sol–gel transition temperature ( T gel ). Their special swelling behavior at certain lower or upper critical solution temperatures (LCST or UCST) has promoted the applications as anti‐fogging and anti‐icing materials through delaying the coalescence of condensed drops and inhibiting ice nucleation and/or growth, respectively.…”