Two colors of light are needed to break bonds and release small molecules from the surface of SiO2-Au core-shell nanoparticles.

The photothermal effect is not able to break bonds and release small molecules from the surface of SiO2-Au core-shell nanoparticles unless the nanosystem is first exposed to visible light. Only after this light triggers the ring-opening reaction of dithienylethene chromophores attached to the surface of the nanoparticles can the heat generated by the NIR light induce reverse Diels-Alder reactions.