Coacervation-triggered hierarchically assembled hydrogels with application as surgical sealant

Adhesive hydrogels possess great potential to be explored as tissue adhesives, surgical sealants, and hemostats. However, it has been a great challenge to develop hydrogels that can function rapidly and controllably on wet, dynamic biological tissues. Inspired by polyphenol chemistry, we introduce a coacervation-triggered shaping strategy that enables the hierarchical assembly of recombinant human collagen (RHC) and tannic acid (TA). The conformation of the RHC and TA aggregates is controlled to evolve from granular to web-like states, accompanied by the significant enhancement of mechanical and adhesion performance. The coacervation and assembly process is driven by intermolecular interactions, especially hydrogen bonding between RHC and TA. Benefitting from the multifaceted nature of polyphenol chemistry, the hierarchically assembled hydrogels revealed excellent properties as surgical sealing materials, including fast gelation time (within 10 s), clotting time (within 60 s), ultrastretchability (strain >10 000%), and tough adhesion (adhesive strength >250 kPa).In vivoexperiments demonstrated complete sealing of severely leaking heart and liver tissues with the assistance ofin situformed hydrogels during 7 d of follow-up. This work presents a highly promising hydrogel-based surgical sealant in wet and dynamic biological environments for future biomedical applications.