Due to their biodegradability and biocompatibility, chitosan-based hydrogels have great potential in regenerative medicine, with applications such as bacteriostasis, hemostasis, and wound healing. However, toxicity and high cost are problems that must be solved for chitosan-based hydrogel crosslinking agents such as formaldehyde, glutaraldehyde, and genipin. Therefore, we developed a biocompatible yet cost-effective chitosan-based hydrogel system as a candidate biomaterial to prevent infection during wound healing. The hydrogel was fabricated by crosslinking chitosan with dialdehyde chitosan (CTS–CHO) via dynamic Schiff-base reactions, resulting in a self-healable and injectable system. The rheological properties, degradation profile, and self-healable properties of the chitosan-based hydrogel were evaluated. The excellent antibacterial activity of the hydrogel was validated by a spread plate experiment. The use of Live/Dead assay on HEK 293 cells showed that the hydrogel exhibited excellent biocompatibility. The results demonstrate that the newly designed chitosan-based hydrogel is an excellent antibacterial wound dressing candidate with good biocompatibility.

Functional conductive hydrogels are widely used in various application scenarios, such as artificial skin, cell scaffolds, and implantable bioelectronics. However, their novel designs and technological innovations are severely hampered by traditional manufacturing approaches. Direct ink writing (DIW) is considered a viable industrial‐production 3D‐printing technology for the custom production of hydrogels according to the intended applications. Unfortunately, creating functional conductive hydrogels by DIW has long been plagued by complicated ink formulation and printing processes. In this study, a highly 3D printable poly(3,4‐ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS)‐based ink made from fully commercially accessible raw materials is demonstrated. It is shown that complex structures can be directly printed with this ink and then precisely converted into high‐performance hydrogels via a post‐printing freeze–thawing treatment. The 3D‐printed hydrogel exhibits high electrical conductivity of ≈2000 S m−1, outstanding elasticity, high stability and durability in water, electromagnetic interference shielding, and sensing capabilities. Moreover, the hydrogel is biocompatible, showing great potential for implantable and tissue engineering applications. With significant advantages, the fabrication strategy is expected to open up a new route to create multifunctional hydrogels with custom features, and can bring new opportunities to broaden the applications of hydrogel materials.

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A kind of commercial hybrid carrageenan (HC)/agarose composite sponge containing κ‐, μ‐, ι‐, and ν‐carrageenan, which could turn into hydrogel and release carrageenan at human body temperature was fabricated for immune stimulation and modulation. Release behavior demonstrated that the hybrid carrageenan contained sponge was mechanically stable and could release carrageenan constantly. RT‐PCR and ELISA experiments showed that the leaching liquor of the sponge could stimulate RAW264.7 from M0 state to a polarized state by secreting more anti‐inflammatory factor IL‐10 than pro‐inflammatory ones, such as, IL‐6 and TNF‐α. Transwell experiments also indicated that the leaching liquor could promote the proliferation of NIH‐3T3 by stimulating RAW264.7 of M0 state after 7 days. Results of particle size and intracellular concentration analyses suggested that the released carrageenan might enter into the cellular interior of RAW264.7 in the form of microgels or protein complexes. The sponge would be a promising candidate for skin wound dressing.