Poly(N-isopropylacrylamide)/poly(methyl methacrylate)/silica hybrid capsules were prepared from inverse Pickering emulsion polymerization. A N-isopropylacrylamide aqueous solution was emulsified into an oil phase containing methyl methacrylate and divinyl benzene by sonication to obtain a W/O Pickering emulsion using modified silica nanoparticles as stabilizers. After the emulsion was polymerized, the hybrid capsules were obtained. The capsule wall contained two layers--a solid particle monolayer and a polymer layer--and the wall thickness could be controlled by adjusting the methyl methacrylate and divinyl benzene concentrations in the continuous oil phase before polymerization. The as-synthesized capsules exhibited temperature-responsive properties. The controlled release experiments showed that the release rate of a model drug from the hybrid capsules could be controlled by adjusting the wall thickness of the capsule or the temperature of the release medium.

A porous magnetic hollow silica nanosphere (MHSN) is a new nanostructured drug carrier for increasing drug loading capability. Keeping the magnetic nanoparticles in the hollow core will limit the toxicity and degradation in a biosystem. In this paper, we report a synthesis of porous MHSNs by sol−gel method. CaCO3/Fe3O4 composite particles were first fabricated by embedding Fe3O4 nanoparticles into CaCO3 using the rotating packed bed (RPB) method. Tetraethoxysilane (TEOS) was then added as precursor to form a silica (SiO2) layer on the surface of CaCO3/Fe3O4 composite particles. Hexadecyltrimethylammonium bromide (CTAB) and octane act as second templates for the formation of porous silica shells. After removing the surfactants by calcination and etching away the CaCO3 particles, porous MHSNs with magnetite (Fe3O4) nanoparticles inside the cores were formed. The pore size can be tuned by adjusting the amount of the cationic surfactant absorbed on the surface of the composite particles to form self-assembled nanochannels. Ibuprofen was loaded on or into the porous MHSNs, and the drug encapsulation and release were investigated. A slow release was observed for the porous MHSNs, which demonstrated MHSNs are potential carriers for controlled releasing in nanomedicine application.

We demonstrate the fabrication of highly open spherical cages with large through pores using high aspect ratio cellulose nanocrystals with "haystack" shell morphology. In contrast to traditional ultrathin shell polymer microcapsules with random porous morphology and pore sizes below 10 nm with limited molecular permeability of individual macromolecules, the resilient cage-like microcapsules show a remarkable open network morphology that facilitates across-shell transport of large solid particles with a diameter from 30 to 100 nm. Moreover, the transport properties of solid nanoparticles through these shells can be pH-triggered without disassembly of these shells. Such behavior allows for the controlled loading and unloading of solid nanoparticles with much larger dimensions than molecular objects reported for conventional polymeric microcapsules.

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