PEO surface-decorated silica nanocapsules and their application in in vivo imaging of zebrafish

To develop a class of robust and colloidally stable silica nanocapsules for bioimaging, we have investigated the interfacial hydrolysis and condensation of silicon alkoxides confined between the PPO core and PEO corona of self-assembled Pluronic® polymeric micelles. The interfacial hydrolysis and condensation, which are completed under the benign conditions of near-neutral pH and at room temperature, give rise to the decoration of silica nanocapsules with a layer of PEO chains dangling on their surface. This feature enables them to be intrinsically stable in aqueous and physiological environments. To demonstrate the silica nanocapsules as effective nanocarriers in bioimaging as well as their biocompatibility, fluorescent conjugated polymer MEH-PPV is encapsulated into the silica nanocapsules and used for in vivo studies with zebrafish as the vertebrate model. When microinjected into the transgenic zebrafish line TG(fli1:EGFP), the cellular internalization of these fluorescent silica nanocapsules does not appear to interfere with larval development nor affect vessel growth. Their biostability is verified by the continued presence of fluorescent-labeled cells in the zebrafish larvae over a long period after the microinjection of fluorescent silica nanocapsules.