Paper SERS substrates for explosives detection using a portable spectrometer

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We have successfully fabricated ecofriendly SERS substrate by using low-cost FP as a base and is embedded with NPs that were also fabricated by a green technique LAL. The common FP with aggregated Ag/Au NPs provided a simple and robust approach for SERS substrate preparation. Specifically, spherical Ag and Au NPs were loaded for an optimally aggregated configuration to yield maximum signal enhancements in the SERS measurements. Our results from detailed experiments presented here indicate that the Ag/Au NPs with 50 mM NaCl concentration is helpful for optimal SERS performance. From the result obtained, we conclude the paper-based Ag substrate performance better than paper-based Au substrate. The optimized active SERS paper substrate is helpful for the detection of four adsorbed molecules (MB-5 nM, PA-5 μM, DNT-1 μM, and NTO-10 μM) with high specificity, sensitivity, and reproducibility. These concentrations in terms of mass represent 31.98 pg, 11.45 ng, 1.82 ng, and 13.06 ng, respectively. Overall, we report here a simple, inexpensive technique for creating plasmonic substrates that are readily integrated with a portable spectrometer for rapid SERS analysis. It offers to decrease the cost of analysis using paper-based SERS targets and utilizing a portable Raman instrument, which is portable to the point of diagnostics of interest. Furthermore, the NPs produced by laser ablation are proven to be stable for long periods of time.44 However, the stability of these NPs when loaded in the FP is being investigated thoroughly. We strongly believe that following further optimization studies, the combination of low-cost and high-performance paper SERS devices will be an ideal platform to enter on-site analysis, beyond the research laboratories, for practical applications related to explosives detection.

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