Dipping into a drink: Basil-seed supported silver nanoparticles as surface-enhanced Raman scattering substrates for toxic molecule detection

Abstract High-density plasmonic Ag nanoparticles (Ag-NPs) have been synthesized on a three-dimensional framework of natural basil seeds as the inexpensive substrates for surface-enhanced Raman scattering (SERS). The Ag-NPs decorated basil seeds (denoted as Ag-NPs@basil-seeds) are dipped into the analyte solution for rapid detection of methyl parathion in orange juice. Alternatively, they are incorporated into a microfluidic chip for online measurement of melamine in milk. The porous basil seeds can absorb trace melamine into the micro-cavity in the seeds, which load the melamine molecules into the gap where high-density “hot spots” appear under laser excitation. Hence the Ag-NPs@basil-seeds not only separate and pre-concentrate the trace analyte but also expose the analyte into the strong plasmonic field. This unique feature can eliminate the pre-treatment of analyte prior to SERS detection, and improve the sensitivity of the sensor.