Surface plasmon resonance scattering and absorption of biofunctionalized gold nanoparticles for targeted cancer imaging and laser therapy

The localized surface plasmon resonance of gold nanoparticles enables them to be excellent light scattering sensing reagents and efficient lignt-heat convertors for potential diagnostics and therapeutics. In this work, gold nanoparticles of 15 nm in size were synthesized and conjugated with a kind of arginine-glycine-aspartic acid peptide (RGD) to target the cancer cells. Under a conventional dark field microscope, the scattering images from normal and cancer cells are very different. Only a few of gold nanoparticles bind to the membrane of normal cells due to nonspecific interaction. Yet for cancer cells, the concentration of gold nanoparticles inside cancer cells is much higher than that inside normal cells, showing a strong light scattering signal. By exposing these cells to an external laser irradiation, cancer cells were selectively destructed because of the heat conversion of gold nanoparticles inside them, but normal cells still kept alive due to the absence of gold nanoparticles in them. These results incidated that gold nanoparticles might be potential contrast reagents for targeted cancer imaging and laser therapy.