Dye-doped polystyrene-coated gold nanorods: towards wavelength tuneable SPASER

We present the synthesis and photophysical study of a new type of fluorescent gold core–polystyrene shell nanoparticles fabricated by emulsion polymerization at neutral pH. The thickness of the PS shell can be controlled by varying the synthesis conditions. Decrease in the fluorescence intensity and lifetime of Rhodamine 800 (Rh800) were observed, indicating energy transfer from Rh800 to gold nanorods. This study suggests the possibility of exploiting dye-doped polystyrene shells as a gain medium to compensate for the energy loss of longitudinal surface plasmon resonance of gold nanorods and paving the way for eventually realizing a SPASER (surface plasmon amplification by stimulated emission of radiation) optical source of tuneable wavelength.