Biocompatible Au@Ag nanorod@ZIF-8 core-shell nanoparticles for surface-enhanced Raman scattering imaging and drug delivery.

A surface-enhanced Raman scattering (SERS) imaging probe and drug carrier based on zeolitic imidazolate framework (ZIF-8)-coated Au@Ag core-shell nanorod has been developed. Strong Raman signal is generated by a reporter molecule of 4-aminothiophenol (4-ATP) adsorbed on Au@Ag core-shell nanorod, endowing the probe with function of SERS imaging. Further coating of ZIF-8 on Au@Ag core-shell nanorod offered high loading capacity for anti-cancer drugs, doxorubicin (DOX), as well as improved the stability and biocompatibility of the SERS tag due to the protection of ZIF-8 shell. After immobilization of folic acid onto the Au@Ag NRs4-ATP@ZIF-8, the SERS probes were successfully applied to the targeted SERS imaging of HeLa, MCF-7, LNCaP, QGY-7703, HCT116 and MDA-MB-231 cells with low cytotoxicity, and further applied to the image of tumor tissue of human colon cancer. In vitro cell cytotoxicity confirmed that DOX-loaded SERS probes had potential therapeutic effect compared with the free drug. All of these original results contribute to develop potential biocompatible nanosystem integrating diagnosis and therapy.