Metal Nanoshell — Capsule for Light-Driven Release of a Small Molecule

We report the release of small molecules from the metal nanoshells driven by the laser irradiation. The metal nanoshells were composed of 50 nm silica cores and variable thick silver shells of 10 and 30 nm. The small molecule fluorophores of Rhodamine 123 were physically absorbed in the silica cores of metal nanoshells and released through the metal walls. The release rate was significantly increased with the laser irradiation depending on the metal shell thickness: a thicker metal nanoshell leads to a faster release. The results were interpreted by the photothermal effect of metal nanoshells that could convert the light into the thermal energy via coupling interactions of light with the metal plasmon resonances of shells. The metal nanoshells may be potentially used as the capsules for the controlled release of drugs as other molecules.