  Photothermal conversion efficiency ({\eta}) plays a crucial role in selecting
suitable gold nanoparticles for photothermal therapeutic applications. The
photothermal efficiency depends on the material used for the nanoparticles as
well as their various parameters such as size and shape. By maximizing the
light-to-heat conversion efficiency ({\eta}), one can reduce the concentration
of nanoparticle drugs for photothermal cancer treatment and apply lower laser
power to irradiate the tumor. In our study, we explored a new hybrid plasmonic
conjugate for theranostic (therapy+diagnostic) applications. We conjugated 20
nm gold nanospheres with cyanine IR dyes, which exhibited significantly
enhanced photothermal properties compared to bare nanoparticles. Moreover, the
improved photothermal properties of the conjugates can be explained by the
synergistic effect that results from the coupling between the metal nanosphere
and organic dye.
