Abstract
Picric acid (PA) is an organic substance widely used in industry and military, which poses a great threat to the environment and security due to its unstable, toxic, and explosive properties. Trace detection of PA is also a challenging task because of its highly acidic and anionic character. In this work, silver nanoparticles (AgNPs)-decorated porous silicon photonic crystals (PS PCs) were controllably prepared as surface-enhanced Raman scattering (SERS) substrates using the immersion plating solution. PA and Rhodamine 6G dye (R6G) were used as the analyte to explore the detection performance. As compared with single layer porous silicon, the enhancement factor of PS PCs substrates is increased to 3.58 times at the concentration of 10−6 mol/L (R6G). This additional enhancement was greatly beneficial to the trace-amount-detection of target molecules. Under the optimized assay condition, the platform shows a distinguished sensitivity with the limit of detection of PA as low as 10−8 mol/L, the linear range from 10−4 to 10−7 mol/L, and a decent reproducibility with a relative standard deviation (RSD) of ca. 8%. These results show that the AgNPs-modified PS PCs substrates could also find further applications in biomedical and environmental sensing.
Highlights
In recent years, ultra-sensitive detection of trace amounts of explosive chemicals has attracted widespread research attention due to the importance of these chemicals in many practical applications, including terrorist attacks, homeland security, and environmental protection [1,2,3,4,5]
AgNO3 (99.8%), hydrofluoric acid, picric acid (PA), and alcohol were purchased from Sinopharm Chemical Reagent Co., Ltd. (Shanghai, China) Rhodamine 6G was purchased from Shanghai Aladdin Bio-Chem Technology Co., Ltd. (Shanghai, China) Monocrystalline Si was purchased from the Nanomaterials 2018, 8, 872
AgNO3 (99.8%), hydrofluoric acid, PA, and alcohol were purchased from Sinopharm Chemical Reagent Co., Ltd. (Shanghai, China) Rhodamine 6G was purchased from Shanghai Aladdin Bio-Chem Technology Co., Ltd. (Shanghai, China) Monocrystalline Si was purchased from the Tianjin Institute of Semiconductor Technology (Tianjin, China)
Summary
Ultra-sensitive detection of trace amounts of explosive chemicals has attracted widespread research attention due to the importance of these chemicals in many practical applications, including terrorist attacks, homeland security, and environmental protection [1,2,3,4,5]. At some sites on a molecule, which can be referred to as “hotspots”, the local electric field becomes very strong; this leads to strong Raman signals from the molecules at these spots Both the morphology and the substrate materials significantly influence the SERS effect. The preparation of porous silicon by anodic electrochemical etching is simple, and the repeatability of the process is very good [30] This method is very suitable for the preparation of porous Si photonic crystals (PS PCs). The porous Si photonic crystals modified by Ag nanoparticles (AgNPs) as a SERS substrate were designed for qualitative identification and quantitative determination of trace amounts of R6G and PA explosives by the SERS method (Scheme 1). ScShcheemmaet1i.cScfhaebmraictiactfiaobrnicoatfiosnilovf esirlvnerannaonoppaarrttiiccleles sinicnorcpoorraptoedraptoeroduspsoilricooun sphsoiltoicnoicncrpyshtaolstonic crystals (PS PCs) for surface-enhanced Raman scattering (SERS)
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