Selective content release from light-responsive microcapsules by tuning the surface plasmon resonance of gold nanorods

We have constructed light-responsive polyelectrolyte microcapsules containing two different kinds of gold nanorods (Au-NRs) on their surface. We also show that they can act as a platform for active and selective release of the model drug Rhodamine 6G (Rh6G) contained in the microcapsules. The Au-NRs were first coated with poly(sodium styrene-4-sulfonate) and then adsorbed onto the surface of the capsules by electrostatic interaction. Confocal laser scanning microscopy reveals that near-infrared light irradiation at 800 nm induces the release of Rh6G from the microcapsules if the longitudinal surface plasmon resonance peak matches the excitation wavelength. In this case, irradiation also causes melting of nanorods as visualized by transmission electron microscopy. We presume that this method is of great value for in-vivo multi-drug delivery in combined therapies.