An Intermediate Unit-Mediated, Continuous Structural Inheritance Strategy for the Dilemma between Injectability and Robustness of Hydrogels

Hydrogels with injectability and robustness have great promise in clinical practice. However, current injectable hydrogels are usually mechanically weak. Here, an idea, "preformed hydrogel reversion", is proposed to develop robust injectable hydrogels through an intermediate unit-mediated, continuous structural inheritance strategy. In this strategy, robust preformed hydrogels are physically disassembled into intermediate injectable structure-inherited microgels (SIMs), and upon encountering water in physiological environment, the SIMs can construct a macroscopical robust structure with the driving force of hydrogen bonds (H-bonds). The physical disassembly and construction process enables the inheritance of robust structures through SIMs, thereby realizing both excellent injectability and robustness. Beyond that, the SIMs also exhibit long-term storage stability and convenient usability. Using protein drug loading and hemostasis as examples, it is demonstrated that the SIM system shows superiorities in biomedical applications. The proposed idea of "preformed hydrogel reversion" can open new horizons for developing robust injectable hydrogels for diverse applications.