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Rocket-like vesicles formed are composed of poly(acrylic aicd) (PMAA )/poly(ethylene glycol) (PEG) complex coated hollow silica spheres, and the structure and composition of the vesicles are characterized using TGA, 1H NMR, FTIR, and TEM. Although only one-third of EG units of PEG brushes grafted to hollow silica spheres form the complex with PMAA via hydrogen bonding, the first 'booster' layer composed of PMAA/PEG complex can provide secure encapsulation of model compound calcein blue under an acidic condition. The second 'booster' layer composed of PEG brushes can be formed by changing acidic pH to 7.4 through the disassociation of the PMAA/PEG complex. A higher molecular weight PMAA exhibits a faster disassembly due to the formation of a looser PMAA/PEG complex on the surfaces of hollow silica spheres. [ABSTRACT FROM AUTHOR]

A surfactant-free emulsion-based approach is developed for preparation of nanogels. A water-in-oil emulsion is generated feasibly from a mixture of water and a solution of disulfide-containing hyperbranched PEGylated poly(amido amine)s, poly(BAC2-AMPD1)-PEG, in chloroform. The water droplets in the emulsion are stabilized and filled with poly(BAC2-AMPD1)-PEG, and the crosslinked poly(amido amine)s nanogels are formed via the intermolecular disulfide exchange reaction. FITC-dextran is loaded within the nanogels by dissolving the compound in water before emulsification. Transmission electron microscopy and dynamic light scattering are applied to characterize the emulsion and the nanogels. The effects of the homogenization rate and the ratio of water/polymer are investigated. Redox-induced degradation and FITC-dextran release profile of the nanogels are monitored, and the results show efficient loading and redox-responsive release of FITC-dextran. This is a promising approach for the preparation of nanogels for drug delivery, especially for neutral charged carbohydrate-based drugs. [ABSTRACT FROM AUTHOR]