Abstract
AbstractCore–shell nanocapsules are receiving increasing interest for drug delivery applications. Silica nanocapsules have been the focus of intensive studies due to their biocompatibility, versatile silica chemistry, and tunable porosity. However, a versatile one‐step preparation of silica nanocapsules with well‐defined core–shell structure, tunable size, flexible interior loading, and tailored shell composition, permeability, and surface functionalization for site‐specific drug release and therapeutic tracking remains a challenge. Herein, an interfacially confined sol–gel process in miniemulsion for the one‐step versatile preparation of functional silica nanocapsules is developed. Uniform nanocapsules with diameters from 60 to 400 nm are obtained and a large variety of hydrophobic liquids are encapsulated in the core. When solvents with low boiling point are loaded, subsequent solvent evaporation converts the initially hydrophobic cavity into an aqueous environment. Stimuli‐responsive permeability of nanocapsules is programmed by introducing disulfide or tetrasulfide bonds in the shell. Selective and sustained release of dexamethasone in response to glutathione tripeptide for over 10 d is achieved. Fluorescence labeling of the silica shell and magnetic loading in the internal cavity enable therapeutic tracking of nanocapsules by fluorescence and electron microscopies. Thus, silica nanocapsules represent a promising theranostic nanoplatform for targeted drug delivery applications.
Highlights
Introduction used for preparingSiO2 NCs as they typically result in welldefined size and shape.[17]
We demonstrated here a versatile one-step synthesis of SiO2 NCs for biomedical applications
This approach is based on a sol–gel process confined at the interface of oil-in-water miniemulsion droplets
Summary
The SiO2 NCs were synthesized via a confined sol–gel process at the nanodroplets-water interface in an oil-in-water miniemulsion. The oil phase forming the nanodroplets consisted in a mixture of silica precursors, osmotic pressure agent, organic solvent, and functional payloads to be encapsulated. This hydrophobic mixture was subsequently dispersed in an aqueous solution of surfactant by ultrasonication (see Figure 1a). By this approach, therapeutic agents were directly encapsulated in the liquid core of nanocapsules during the shell formation. Functional silica precursors, i.e., alkoxysilanes containing amino groups, fluorescent probes, or redox-responsive disulfide bonds, can be integrated in the silica shell to achieve multiple control for the morphology, cargo loading, shell composition, and functionality in one step
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