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Fabrication of versatile hydrogels in a facile and effective manner represents a pivotal challenge in the field of biomaterials. Herein, a novel strategy is presented for preparing on‐demand degradable hydrogels with multilevel responsiveness. By employing selenol‐dichlorotetrazine nucleophilic aromatic substitution (SNAr) to synthesize hydrogels under mild conditions in a buffer solution, the necessity of additives or posttreatments can be obviated. The nucleophilic and redox reactions between selenol and tetrazine culminate in the formation of three degradable chemical bonds—diselenide, aryl selenide, and dearomatized selenide—in a single, expeditious step. The resultant hydrogel manifests exceptional adaptability to intricate environments in conjunction with self‐healing and on‐demand degradation properties. Furthermore, the resulting material demonstrated light‐triggered antibacterial activity. Animal studies further underscore the potential of integrating metformin into Se‐Tz hydrogels under green light irradiation, as it effectively stimulates angiogenesis and collagen deposition, thereby fostering efficient wound healing. In comparison to previously documented hydrogels, Se‐Tz hydrogels exhibit controlled degradation and drug release, outstanding antibacterial activity, mechanical robustness, and bioactivity, all without the need for costly and intricate preparation procedures. These findings underscore Se‐Tz hydrogels as a safe and effective therapeutic option for diabetic wound dressings. [ABSTRACT FROM AUTHOR]

Electroactive hydrogels, which exhibit intelligent deformation in response to electric fields, have garnered significant attention as potential actuating materials for flexible sensors, smart devices, soft actuators, and artificial muscles. In the process of converting mechanical energy to electrical energy, electroactive hydrogels can achieve efficient energy conversion and charge transfer due to their porous structure, high water solubility, flexibility, and electrical conductivity. However, the limited performance of single-functional electroactive hydrogels severely hampers their development prospects. To expand the application areas of these gels in self-powered devices, smart response devices, and other directions, there is a need to design electroactive hydrogels with multiple properties. In this paper, we present a systematic review of the mechanism and preparation strategies of electroactive hydrogels in response to electric fields. We also discuss the design strategy for electroactive hydrogels with multiple properties and provide an overview of the current progress in their applications. Furthermore, we analyze the role and advantages of electroactive hydrogels. Finally, we address the existing problems in electroactive hydrogel research and offer suggestions to solve them, and we hope that this design idea will inspire readers and researchers in the field. The article reviews the mechanism behind the generation of electroactive hydrogels and the design strategy of electroactive hydrogels with different properties, and describes the current status and challenges of their application areas. [Display omitted] • Exploring the mechanism and preparation of electroactive hydrogels. • Discussing the significance of electroactive hydrogels in various applications. • Examining the challenges and potential opportunities of electroactive hydrogels. [ABSTRACT FROM AUTHOR]

• Chlorella incorporated into hydrogels for continuous oxygen and bioelectric delivery. • Hydrogels offer mechanical support and create optimal microenvironment for Chlorella. • Hydrogels improve diabetic wound healing by enhancing proliferation and angiogenesis. Electrical stimulation and oxygen are vital for promoting cell proliferation, migration, and differentiation to repair damaged tissues in chronic wound healing in patients with diabetes. The effective oxygen production by Chlorella has garnered attention in the medical field, but the potential of extracellular electron production in skin repair has not been explored. Inspired by this, we developed CHPS hydrogels, a composite of polyacrylamide and sodium alginate, with Chlorella loaded in a semi-interpenetrating network. This network is formed by crosslinking acrylamide initiated by free radicals, with alginate chains dispersed within the network. When applied to wounds, CHPS hydrogels effectively protect damaged tissue, provide mechanical support to Chlorella against external forces, and create an optimal artificial microenvironment to promote the proliferation of Chlorella. Our study demonstrated that CHPS hydrogels exhibit remarkable fracture elongation and adhesion properties and continuously produce oxygen and bioelectrical currents through photosynthesis. Furthermore, the sustained release of dissolved oxygen and bioelectricity by CHPS hydrogels significantly enhances cell proliferation, migration, and angiogenesis, leading to improved wound healing in diabetic mice. These findings provide compelling evidence for further exploration of CHPS hydrogels as a cost-effective, simple, and accessible strategy for enhancing the clinical treatment of chronic wounds in diabetic patients. [ABSTRACT FROM AUTHOR]

[Display omitted] • Au-loaded mesoporous silica/gelatin hydrogel was used the excellent humidity sensing film. • The prepared sensor could detect NH 3 by utilizing the outstanding ability to adsorb water molecules. • An egg storage scenario was simulated, and the water loss in eggs was monitored by the humidity sensor. • The sensing mechanism and contribution of each component in the sensing process were analyzed. In this paper, a composite hydrogel film (Au/Me-SiO 2 /G) based on Au nanoparticles, mesoporous silica and gelatin was prepared, which can be used for low relative humidity (RH) detection. Au-1%/Me-SiO 2 /G exhibits a response of 423% in the range of 0.4–30% RH, a short response time of 28 s, a linearity of R2 = 0.997, and good long-term stability. With the outstanding ability to adsorb water molecules, the sensor can detect NH 3 at room temperature and low humidity environment. The response of the sensor to NH 3 significantly increases with the humidity. At 30% RH, the initial impedance value of the sensor is as low as ∼6.6 MΩ, and the response to 50 ppm NH 3 is 78%. In addition, an egg storage scenario was simulated, and the water loss in eggs was monitored simultaneously by the prepared humidity sensor and a commercial sensor. The results demonstrate the practical application detection ability of the prepared humidity sensor. [ABSTRACT FROM AUTHOR]