Fluorescent hollow/rattle-type mesoporous Au@SiO2 nanocapsules for drug delivery and fluorescence imaging of cancer cells

Multifunctional uniform and versatile hollow and rattle-type nanocapsules composed of spindle-shaped Au nanoparticles as cores and fluorescent mesoporous silica shells with tunable optical and fluorescent properties have been developed by controlled etching Au nanorods (AuNRs) coated with mesoporous SiO2 (AuNR@mSiO(2)) via a small amount of aqua regia (volume ratio HCl/HNO3 = 3/1) as an etching agent in a facile way. The etching process can be tracked by UV-Vis absorption and fluorescence spectroscopy and the size of cavities in the hollow/rattle-type particles can be tuned by controlling the reaction time. The dye molecules incorporated in mSiO(2) walls enabled the nanocapsules to be utilized as a fluorescent imaging agent in cancer cell imaging. Furthermore, such hollow/rattle-structured nanocapsules have the merit of enhanced drug loading capacity acting as carriers for the loading and delivery of an anticancer drug, doxorubicin hydrochloride (DOX), with higher storage for cancer therapy. Herein, the combined functionalities of simultaneous cell imaging and drug delivery of the synthesized nanocapsules have been demonstrated, which provide a very promising candidate for application in optical imaging and drug delivery for cancer cells. (c) 2011 Elsevier Inc. All rights reserved.