Hofmeister Effect-Assisted Strong Natural Biopolymer-Based Hydrogels with Multi-Functions

Natural biopolymer-based hydrogels have been extensively studied in recent years due to their excellent biocompatibility.However,the preparation of multi-functional and tough natural biopolymer-based hydrogels is still a challenging problem.Herein,a natural biopolymer-based hydrogel is prepared using gelatin and carboxymethyl chitosan(CMCS)through a one-step soaking method.The prepared hydrogel without any synthetic polymers and crosslinking agents has a fully physical crosslinking structure.Due to the hydrophobic interaction brought by the Hofmeister effect,the mechanical properties of soaked hydrogels(tensile stress and strain can reach 3.77 MPa and 1082%)are superior to conventional protein hydrogels.In addition,the prepared gelatin/carboxymethyl chitosan(Gel/CMCS)hydrogels exhibit a variety of appealing properties,including good shape memory,fatigue resistance,electrical conductivity,water retention,drug releasing,antibacterial property,and recyclability.This strategy opens up a new horizon to fabricate hydrogels with excellent mechanical properties and multiple functions,which can extend their applications in the biomedicine area and other related fields.

A metal ions-mediated natural small molecules carrier-free injectable hydrogel achieving laser-mediated photo-Fenton-like anticancer therapy by synergy apoptosis/cuproptosis/anti-inflammation

Tumor microenvironment (TME) plays an important role in the tumorigenesis, proliferation, invasion and metastasis. Thereby developing synergistic anticancer strategies with multiple mechanisms are urgent. Copper is widely used in the treatment of tumor chemodynamic therapy (CDT) due to its excellent laser-mediated photo- Fenton-like reaction. Additionally, copper can induce cell death through cuproptosis, which is a new modality different from the known death mechanisms and has great promise in tumor treatment. Herein, we report a natural small molecules carrier-free injectable hydrogel (NCTD Gel) consisted of Cu2+-mediated self-assembled glycyrrhizic acid (GA) and norcantharidin (NCTD), which are mainly governed by coordination and hydrogen bonds. Under 808 nm laser irradiation, NCTD Gel can produce reactive oxygen species (ROS), consume glutathione (GSH) and overcome hypoxia in TME, leading to synergistically regulate TME via apoptosis, cuproptosis and anti-inflammation. In addition, NCTD Gel’s CDT display high selectivity and good biocompatibility as it relies on the weak acidity and H2O2 overexpression of TME. Notably, NCTD Gel’s components are originated from clinical agents and its preparation process is easy, green and economical, without any excipients. This study provides a new carrier-free hydrogel synergistic antitumor strategy, which has a good prospect in industrial production and clinical transformation.

Natural polymer-based adhesive hydrogel for biomedical applications

Hydrogel is a polymer network system that can form a hydrophilic three-dimensional network structure through different cross-linking methods.In recent years,hydrogels have received considerable attention due to their good biocompatibility and biodegradability by introducing different cross-linking mechanisms and functional components.Compared with synthetic hydrogels,natural polymer-based hydrogels have low biotoxicity,high cell affinity,and great potential for biomedical fields;however,their mechanical properties and tissue adhesion capabilities have been unable to meet clinical requirements.In recent years,many efforts have been made to solve these issues.In this review,the recent progress in the field of natural polymer-based adhesive hydrogels is highlighted.The authors first introduce the general design principles for the natural polymer-based adhesive hydrogels being used as excellent tissue adhesives and the challenges associated with their design.Next,their usages in biomedical applications are summarised,such as wound healing,haemostasis,nerve repair,bone tissue repair,cartilage tissue repair,electronic devices,and other tissue repairs.Finally,the potential challenges of natural polymer-based adhesive hydrogels are presented.

3D direct printing of mechanical and biocompatible hydrogel meta-structures

Direct Ink Writing(DIW)has demonstrated great potential as a versatile method to 3D print multifunctional structures.In this work,we report the implementation of hydrogel meta-structures using DIW at room temperature,which seamlessly integrate large specific surface areas,interconnected porous characteristics,mechanical toughness,biocompatibility,and water absorption and retention capabilities.Robust but hydrophobic polymers and weakly crosslinked nature-origin hydrogels form a balance in the self-supporting ink,allowing us to directly print complex meta-structures without sacrificial materials and heating extrusion.Mechanically,the mixed bending or stretching of symmetrical re-entrant cellular lattices and the unique curvature patterns are combined to provide little lateral expansion and large compressive energy absorbance when external forces are applied on the printed meta-structures.In addition,we have successfully demonstrated ear,aortic valve conduits and hierarchical architectures.We anticipate that the reported 3D meta-structured hydrogel would offer a new strategy to develop functional biomaterials for tissue engineering applications in the future.