A positively charged silver nanowire membrane for rapid on-site swabbing extraction and detection of trace inorganic explosives using a portable Raman spectrometer

The sensitive and on-site detection of inorganic explosives has raised serious concerns regarding public safety. However, high stability and non-volatility features currently limit their rapid on-site detection. Surface-enhanced Raman spectroscopy (SERS) is emerging as a powerful technique for the trace-level detection of different molecules. Plasmonic Ag nanowires were produced by a hydrothermal synthesis method using polyvinylpyrrolidone (PVP) as a negatively charged stabilizer. Here, we report a rapid detection method for inorganic explosives based on a simple surface swab with a positively charged diethyldithiocarbamate-modified Ag nanowire membrane coupled with SERS. This membrane, serving as an excellent SERS substrate with high uniformity, stability, and reusability, can capture both typical oxidizers in inorganic explosives and organic nitro-explosives, via electrostatic interaction. The detection level of perchlorates (ClO 4 − ), chlorates (ClO 3 − ), nitrates (NO 3 − ), picric acid, and 2,4-dinitrophenol is as high as 2.0, 1.7, 0.1, 45.8, and 36.6 ng, respectively. In addition, simulated typical inorganic explosives such as black powders, firecrackers, and match heads could also be detected. We believe that this membrane represents an attractive alternative for rapid on-site detection of inorganic explosives with high efficiency.