Double-walled Au nanocage/SiO2 nanorattles: integrating SERS imaging, drug delivery and photothermal therapy.

In this work, a novel type of nanomedical platform, the double-walled Au nanocage/SiO(2) nanorattle, is successfully fabricated by combining two "hollow-excavated strategies"--galvanic replacement and "surface-protected etching". The rational design of double-walled nanostructure based on gold nanocages (AuNCs) and hollow SiO(2) shells functionalized respectively with p-aminothiophenol (pATP) and Tat peptide simultaneously renders the nanoplatforms three functionalities: 1) the whole nanorattle serves as a high efficient drug carrier thanks to the structural characteristics of AuNC and SiO(2) shell with hollow interiors and porous walls; 2) the AuNC with large electromagnetic enhancement acts as a sensitive surface-enhanced Raman scattering (SERS) substrate to track the internalization process of the nanorattles by human MCF-7 breast cancer cells, as well as an efficient photothermal transducer for localized hyperthermia cancer therapy due to the strong near-infrared absorption; 3) Tat-functionalized SiO(2) shell not only improves biocompatibility and cell uptake efficiency resulting in enhanced anticancer efficacy but also prevents the AuNCs from aggregation and provides the stability of AuNCs so that the SERS signals can be used for cell tracking in high fidelity. The reported chemistry and the designed nanostructures should inspire more interesting nanostructures and applications.