Spiers Memorial Lecture: Recent advances (and challenges) in supramolecular gels

Supramolecular hydrogels are physical hydrogels that are formed by non-covalent interactions such as hydrogen bonding, electrostatic attraction, hydrophobic interactions, and π-π stacking. Compared to typical, chemically cross-linked hydrogels, supramolecular networks commonly have stimuli-responsive behavior including reversibility and injectability, which are being widely studied for uses in drug delivery, tissue engineering, and wound healing. This review highlights recent developments in supramolecular network design and behavior focusing on the different possible molecular building blocks, including peptides, polysaccharides, synthetic polymers, and multicomponent systems. We further discuss self-assembly mechanisms of hydrogel formation, as well as recent advances in stimuli-responsive supramolecular hydrogels triggered by pH, temperature, and light. Advanced characterization techniques such as rheological analysis, spectroscopy, scattering methods, and electron microscopy are summarized to understand hydrogel structure, assembly pathways, and ultimate network properties. This review provides readers with an updated understanding of supramolecular hydrogels and highlights current research presented during the <i>Faraday Discussions</i> meeting on advances in supramolecular gels, promoting the rational design and development of novel materials to address complex biomedical and other technological challenges.