Light-Activatable Theranostic Agents for Image-Monitored Controlled Drug Delivery.

A novel drug delivery vehicle using nanodroplets activated by light irradiation for drug release in a controlled manner has been developed. The drug encapsulated in the nanodroplets was released upon phase transition from a liquid droplet to microbubbles (vaporization) by plasmonic photothermal heat from gold nanorods adsorbed on the surface of the nanodroplets. The nanodroplets were stable against aggregation and dissolution at 4 °C over 3 months to date. The phase transition was quantitatively analyzed by ultrasound imaging to examine the amount of drug release noninvasively. In vitro studies showed that cell death occurred only when light irradiation was performed on the drug-encapsulated nanodroplets. Ex vivo studies demonstrated a potential application of the nanodroplets for treating posterior eye diseases. Thus, it has been demonstrated that our gold-nanorod-coated light-activatable nanodroplets can be a candidate for a controlled release and a dosage-monitored drug delivery system.