Plasmonic metal nanoparticle functionalization for selective sensing of persistent pollutants by surface-enhanced Raman scattering

In this work we report on the promising application of combined systems integrated by plasmonic metal nanoparticles and host molecules to the study and detection of persistent pollutants at trace concentrations by Surface-enhanced Raman scattering (SERS). The host molecules used to functionalize the nanoparticles were of synthetic (calixarenes) and natural (humic acids) origins. The calixarenes employed in this study were cycles of four benzene rings with carboethoxy and dithiocarbamate functionalization in the lower rim. The application of surface-enhanced optical techniques, such as SERS, to carry out the characterization of functionalized metal nanoparticles and their complexes with analytes was very useful, not only to detect the ligand at very low trace concentration but also to obtain information about the interaction mechanism. Functionalization of metal nanoparticles was aimed to increase the sensitivity and selectivity in analytical detection of pollutants. Important technological applications are gathered in these systems; a powerful spectroscopy technique such as SERS, the electronic properties of plasmonic nanostructured metals and the molecular size-selective recognition of the used molecular host species.