Polyphenol-Incorporated Composite Nanogels of Multimodal Interactions for Enhanced Gel Stability and Cisplatin Delivery

Naturally abundant polyphenols that can readily undergo the facile cross-linking of polymer chains have been of great interest for functional hydrogel formation and its potential biomedical applications. Herein, we report that the internal incorporation of tannic acid (TA) as a natural polyphenol additive at the chitosan-based nanogel templates can enhance the self-association of physically cross-linked polymer networks upon dilution, as well as the colloidal gel stability in protein solution. This is driven by the multivalent hydrogen bonding and π-stacking capability of TA, as verified by the viscosity estimation of diluted nanogel solution, coupled to the conformation-dependent excimer emission of stacked fluorophores in polymer networks, which also allows for the Stern–Volmer analysis of the TA-induced quenching property. Furthermore, the excellent coordination generality of TA for versatile metallic cations enables the facile immobilization of a cisplatin pharmacophore inside the nanogels for acid-sensitive drug release and the potential delivery of metallic components.