Plasmonic nanosensor based on Ag nanocubes of high purification by extraction filtration strategy for SERS determination of malachite green in aquaculture water

The purity of the nanoassembly blocks is crucial for the construction of efficient nanosensors. In this work, a robust and effective extraction filtration strategy was proposed to improve the purification of Ag nanocubes (NCs) synthesized by the conventional seed-mediated growth method. Generally, the preparation of large-sized Ag NCs requires longer growth time, leading to the presence of numerous independently nucleated nanowires (NWs) impurities in the product. An extraction filtration approach combined with a filter membrane with suitable pore size was employed to effectively retain the Ag NWs on the filter membrane and thus Ag NCs with high purity could be produced. In particular, the pore size and layer numbers of the membrane were systematically optimized to achieve successful purification of Ag NCs with different sizes. Meanwhile, the highly purified Ag NCs were absorbed on the Si wafer by three-phase interface assembly technique to construct the sensitive SERS plamonics substrate. Furthermore, the identification of malachite green (MG) in aquaculture water was successfully demonstrated based on this SERS platform combined with efficient dynamic sampling method. This versatile and facile extraction filtration approach opens a novel avenue to fabricate highly purified noble metal nanoparticles with promising prospects in various fields including electronic, medical, biological and food safety fields.