Figure 3.

Synthesis of nanogels by cross-linking of the preformed polymer chains or self-assembled polymeric aggregates. (a) Cross-linking of double-end activated PEG and PEI chains in o/w emulsion followed by evaporation of the organic solvent. (b) Conjugation of PEI to double end activated Pluronic block copolymer (PEG-PPG-PEG), which is self-assembled in polymeric micelles in aqueous solution, results in nanogels containing hydrophobic PPG domains and cross-linked PEI-PEG network. (c) PEG-b-PMA diblock copolymer is condensed in presence of divalent metal cations in aqueous solution into a micelle with a polyion-metal core and PEG corona. This is followed by cross-linking of the micelle core and removal of the condensing metal cations, which results in nanogels with cross-linked polyanion (PMA) core and PEG corona.