Mild oxidation of thiofunctional polymers to cytocompatible and stimuli-sensitive hydrogels and nanogels

Nanogels consist of three dimensionally cross-linked hydrophilic polymer chains and can thus be easily modified through functionalization of the polymeric building blocks, for example to yield stimuli-sensitive materials. For drug transport and intracellular release, redox-sensitive systems are especially of interest, as the intracellular space is reductive. In this study, parameters that allow preparation of nanogels with tunable size between 150 and 350 nm are systematically evaluated and identified. Most importantly, a new and mild oxidation catalyst, alloxan, is introduced for the preparation of the nanogels. This broadens the range of possible payloads to more-sensitive molecules. Particle stability, degradation in cytosolic conditions, and cytocompatibility in concentrations up to 10 mg · mL(-1) are demonstrated.