SERS-active liposome@Ag/Au nanocomposite for NIR light-driven drug release.

It is important to control drug release and detect the distribution of drug molecules before and after release. In this work, liposome@AgAu nanocomposite is prepared for drug delivery, which not only can control drug release by near infrared laser irradiation but also can monitor drug molecules by surface enhanced Raman scattering (SERS) and fluorescence signal during the release process. The liposome@AgAu core/shell nanocomposite prepared by the galvanic replacement reaction (GRR) shows tunable localized surface plasmon resonance (LSPR) absorption peaks from visible to near-infrared region and good biocompatibility. Comparing to pure doxorubicin (DOX) molecules, liposome@AgAu nanocomposite loading DOX exhibit lower cytotoxicity by MTT assay. After loading into liposome@AgAu, the fluorescence signal of DOX disappear due to the fluorescence resonance energy transfer from DOX to metals shell. On the contrary, the SERS signal of DOX in liposome@AgAu is obviously increased. Furthermore, the liposome@AgAu nanocomposite shows photothermal conversion ability under resonance laser irradiation. Under 633nm laser irradiation, the liposome@AgAu nanocomposite loading DOX can release drug molecules for killing cancer cell. Meanwhile, the fluorescence signal from DOX appears after drug release from liposome@AgAu, but the SERS signal is not obvious. Therefore, this nanocomposite can provide a platform for photothermal controllable drug release and optical signal targeting for drug molecules.