3D structured laser engraves decorated with gold nanoparticle SERS chips for paraquat herbicide detection in environments

Fabrication of SERS-active substrates is a thrust area of research in the field of SERS. Here, we report the fabrication of a new SERS-active substrate composed of Au nanostructures grown on aluminum sheets marked with laser lines (L-Mark SERS chips). The SERS activity of these SERS chips exploited with environmentally important herbicide, paraquat, and dye molecule of methylene blue. Density functional theory (DFT) calculation was performed to theoretically study the molecular structure and Raman vibrational modes of the paraquat. A detailed discussion has been devoted to uniformity, reproducibility, and practical utility of the fabricated substrates. Especially, great amount of discussion has been given to paraquat detection in soil extracts. The results emanate the ultra-sensitive detection of paraquat, uniform enhanced signals over the substrates, and high reproducibility. The report successfully demonstrated the detection of paraquat in drinking water, tap water, agriwater, environmental water, and soil extracts. Liquid chromatography-mass spectrometry (LCeMS) measurements were also performed to demonstrate the realiability of the SERS method. The L-Mark SERS chips based paraquat detection is simple, rapid, and sensitive. We propose that the present sensors hold the potential to be used in herbicide detection and monitoring in-the-field experiments.