Photoluminescence characterization of ZnS-AgInS2 (ZAIS) nanoparticles adsorbed on plasmonic chip studied with fluorescence microscopy

Quantum dots (QDs) are semiconductor nanoparticles showing many advantages for photoluminescence (PL) applications. Since common QDs contain toxic elements such as Cd, Pb, Se, and Te, ZnS-AgInS2 (ZAIS) has been developed as a quantum nanomaterial with low cytotoxicity. In this study, ZAIS@ZnS core-shell QDs coated with carboxyl groups (ZAIS@ZnS-MPA) were prepared as water-soluble nanoparticles. The PL characteristics of ZAIS@ZnS-MPA were studied on a plasmonic chip, which is a substrate with wavelength-scale periodic structures coated with thin metal films, and the PL enhancement of ZAIS by an electromagnetic field derived from grating-coupled surface plasmon resonance (GC-SPR) was also evaluated. The PL spectroscopic characteristics obtained on the grating patterns with a 480 nm-pitch were enhanced in a wider wavelength range. Furthermore, photobleaching, which occurs in conventional fluorescence molecules, was not observed under halogen lamp illumination. The PL and spectroscopic imaging under a microscope indicated the PL characteristics of the ZAIS@ZnS-MPA nanoparticles on the plasmonic chip under appropriate conditions.