A self-healing hydrogel enriched with properties from a double-dynamic network (DDN) that has been prepared via two dynamic linkages (imine and borate ester) by using a single polymeric cross-linker. The four-component Ugi reaction was used for easily synthesizing multifunctional poly­(ethylene glycol) (MF-PEG) with a benzaldehyde group and phenylboronic acid group at each end of the chain. This MF-PEG simultaneously cross-linked with poly­(vinyl alcohol) through the borate ester and glycol chitosan via an imine to generate a self-healing hydrogel with a unique DDN structure in seconds under mild conditions (pH ≈ 7, 25 °C). The prepared hydrogel showed enhanced strength and mucoadhesive abilities because of the complimentary interpenetrating dynamic networks. The DDN hydrogel showed satisfying biocompatibility and was further used in an in vivo mouse model. The hydrogel was injected to successfully deliver an antitumor drug and achieved a superior performance compared to traditional delivery methods. To the best of our knowledge, this is the first report of using the Ugi reaction to prepare a DDN self-healing hydrogel. We hereby propose a general strategy for the facile preparation of self-healing materials with improved properties. The strategy also opens a new avenue for synthesizing multifunctional/reinforced materials with the combination of dynamic chemistry and multicomponent reactions.

Cytotoxicity of PEG oligomers (with different molecular weights) and PEG based monomers (with different chain end groups) was studied in detail.

Engineering biocompatible hydrogels using functional nanoparticles has attracted considerable attention because of their uniquely appealing cooperative effects that can enable multimodality imaging and treatment with improved efficacy against serious diseases. However, the effects of high‐content nanoparticle dopants on the rheological properties of hydrogels frequently lead to an unsatisfactory therapeutic result, which is particularly notable in the design of magnetic hydrogel formulations for cancer therapy. Herein is reported a novel magnetic hydrogel functionalized by ferromagnetic vortex‐domain iron oxide (FVIOs) with optimally adaptive functions for prevention of breast cancer recurrence. The FVIOs can perfectly incorporate into the dynamic hydrogel networks with an extremely low concentration (0.6 mg mL−1), 17 times lower than that of conventional superparamagnetic iron oxide nanoparticles with sufficient heating capacity. Such magnetic hydrogels exhibit high inductive heating and remarkable rheological properties simultaneously. Moreover, the self‐healing, self‐conformal ability, controlled release of loaded doxorubicin, biodegradation, and pH‐responsiveness of the magnetic hydrogel project their efficient sustainable therapeutic ability. In vivo postoperative treatment has further demonstrated the high efficacy of FVIO‐based magnetic hydrogels, as evidenced by the significant suppression of the local tumor recurrences compared to chemotherapy or hyperthermia alone. This unique magnetic hydrogel formulation with optimally adaptive functions shows strong potential in preventing relapses of various cancers.

Biological tissues can automatically repair themselves after damage. Examples include skin, muscle, soft tissue, etc. Inspired by these living tissues, numerous self-healing hydrogels have been developed recently. Chitosan-based self-healing hydrogels constructed via dynamic imine bonds have been widely studied due to their simple preparation, good biocompatibility, and automatic reparability under physiological conditions. In this mini-review, we highlighted chitosan-based self-healing hydrogels based on dynamic imine chemistry, and provided an overview of the preparation of these hydrogels and their bioapplications in cell therapy, tumor therapy, and wound healing.

Smart materials that can respond to multistimuli have been broadly studied. However, the smart materials that can spontaneously answer the ever-changing inner environment of living bodies have not been reported. Here, we report a strategy based on the dynamic chemistry to develop possible self-adapting solid materials that can automatically change shape without external stimuli, as organisms do. The self-adapting property of a chitosan-based self-healing hydrogel has been rediscovered since its dynamic Schiff-base network confers the unique mobility to that solid gel. As a result, the hydrogel can move slowly, like an octopus climbing through a narrow channel, only following the natural forces of surface tension and gravity. The fascinating self-adapting feature enables this hydrogel as an excellent drug carrier for the in vivo wound treatment. In a healing process of the rat-liver laceration, this self-adapting hydrogel demonstrated remarkable superiority over traditional drug delivery methods, suggesting the great potential of this self-adapting hydrogel as a promising new material for biomedical applications. We believe the current research revealed a possible strategy to achieve self-adapting materials and may pave the way toward the further development, study, and application of new-generation smart materials.