Near-Infrared Responsive Gold-Layersome Nanoshells

Anionic liposomes-coated with cationic polyelectrolyte poly-L-lysine (PLL), or layersomes, were used as soft, self-assembled templates for synthesizing gold nanoshells that absorb near-infrared radiation. The gold nanoshells,were formed using two techniques: (a) direct reduction of tetrachloroauric add On the layersomes and (b) the reduction of a tetrachloroauric acid/potassium carbonate growth solution on nanosized gold seeds bound to the surface of layersomes. The resulting structures were characterized by transmission and scanning electron microscopy and visible-near-infrared spectroscopy. Direct reduction produced discrete gold nanoparticles on the layersomes. The slower reduction from the growth solution on the gold seeds resulted in more complete shells. The absorption spectra,of these suspensions were sensitive to the synthesis method. The morphology of the gold shell's Was tuned for absorption at biologically safe and tissue-penetrating NIR wavelengths, and laser irradiation at 810 ruin produced significant heat These gold layersome nanoshells have the potential to be used for photothermal therapy, photothermally mediated drug delivery, and biomedical imaging.