Functional hydrogels for biomedical applications: linking rheology and network structure to performance

Hydrogels combine high water content with tunable mechanical, interfacial, rheological, and transport properties, supporting their use in wound management, surgical adhesion and sealing, controlled drug delivery, and cosmetic and topical formulations. This review examines how these coupled properties govern hydrogel performance across different biomedical and topical applications, with rheology providing a framework for linking network structure and time-dependent mechanical behavior to handling, tissue contact, and functional stability. Across these applications, material design requires coordinated control of processability, conformability, interfacial retention, molecular transport, and functional lifetime. Changes in crosslinking, reversible interactions, swelling, and degradation can improve one function while altering others, emphasizing the need to evaluate hydrogel properties as an interdependent system rather than as isolated parameters. Rheological measurements can help characterize these relationships when interpreted together with adhesion, transport, degradation, and biological performance. The resulting design principles emphasize maintaining an application-specific combination of properties throughout the intended period of use. Future progress will require standardized and application-relevant testing under physiologically relevant fluid exposure and mechanical loading, together with reproducible performance after processing, storage, and sterilization where required. Establishing quantitative relationships among composition, rheological behavior, and functional outcomes may further support more systematic formulation design and translation.