Simultaneous Imaging and Selective Photothermal Therapy through Aptamer-Driven Au Nanosphere Clustering.

Gold (Au) nanoparticles display enhanced near-infrared (NIR) photothermal effects upon the formation of clusters. We studied the photothermal properties of Au nanosphere clusters on the single-particle level using photothermal heterodyne imaging (PTHI) microscopy to understand the enhancement mechanisms. NIR photothermal responses of Au nanoparticle clusters were found to significantly increase from monomers to trimers. The averaged PTHI signal intensity of Au nanosphere dimers and trimers is ∼10 and ∼25 times that of monomers. The NIR photothermal effect of clustered nanospheres strongly correlates with their longitudinal plasmon mode. Clustered Au nanospheres were demonstrated to exhibit dual-capability NIR photothermal imaging and therapy of human prostate cancer cells with high efficiency and selectivity. This strategy can be potentially utilized for simultaneous cancer imaging and therapy with 3D selectivity.