Nanogels inverse emulsion

FIGURE 16.2 Preparation of nanogels by the inverse emulsion method. Aqueous solution of major components for microgel synthesis (hydrophilic polymer molecules and cross-linkers, or monomers, crosslinkers, and reaction initiators) is dispersed in the presence of surfactant in nonmiscible organic solvent and sonicated to form a fine water-in-solvent dispersion. The cross-linked microgel network was formed inside the dispersed aqueous microcontainers and then purified from the surfactant and low-MW reactants by extraction and dialysis. 

Various heterogeneous polymerization reactions of hydrophilic or water-soluble monomers in the presence of either difnnctional or multifunctional cross-linkers have been mostly utilized to prepare weU-defined synthetic nanogels. They include precipitation, inverse (mini)emulsion, and inverse micio ulsion polymerization utilizing an uncontrolled free radical polymerization process. 

In another study, thiol-funaionalized HA was used for the preparation of disulfide aoss-linked nanogels with physically entrapped green fluorescence protein siRNA by an inverse w/o emulsion approach. The same group prepared disulfide-cross-linked HA miaogds and prepared shell cross-linked HA/polylysine layer-by-layer polyelectrolyte microcapsules through layer-by-layer approach followed by the removal of the reducible HA miaogd cores with dithiothreitol (DTT). ... 

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