Collagen-Hyaluronic Acid Composite Hydrogels with Applications for Chronic Diabetic Wound Repair.

Chronic diabetic wounds have become a major healthcare challenge worldwide. Improper treatment may lead to serious complications. Current treatment methods including biological and physical methods and skin grafting have limitations and disadvantages, such as poor efficacy, inconvenience of use, and high cost. Therefore, developing a more effective and feasible treatment is of great significance for the repair of chronic diabetic wounds. Hydrogels can be designed to serve multiple functions to promote the repair of chronic diabetic wounds. Furthermore, 3D bioprinting enables hydrogel customization to fit chronic diabetic wounds, thus facilitating the healing process. This paper reports a study of 3D printing of a collagen-hyaluronic acid composite hydrogels with application for chronic diabetic wound repair. In situ printed hydrogels were developed by a macromolecular crosslinking network using methacrylated recombinant human collagen (RHCMA) and methacrylated hyaluronic acid (HAMA), both of which can respond to ultraviolet (UV) irradiation. The hydrogels were also loaded with silver nanoclusters (AgNCs) with ultra-small-size nanoparticles, which have the advantages of deep penetration ability and broad-spectrum high-efficiency antibacterial properties. The results of this study show that the developed RHCMA, HAMA, and AgNCs (RHAg) composite hydrogels present good UV responsiveness, porosity, mechanical properties, printability, and biocompatibility, all of which are beneficial to wound healing. The results of this study further show that the developed RHAg hydrogels not only effectively inhibited Staphylococcus aureus and Pseudomonas aeruginosa but also promoted the proliferation and migration of fibroblasts in vitro and tissue regeneration and collagen deposition in vivo, thus producing a desirable wound repair effect and can be used as an effective functional biomaterial to promote chronic diabetic wound repair.

Fluid-driven hydrogel actuators with an origami structure.

Owing to the innate good biocompatibility, tissue-like softness and other unique properties, hydrogels are of particular interest as promising compliant materials for biomimetic soft actuators. However, the actuation diversity of hydrogel actuators is always restricted by their structure design and fabrication methods. Herein, origami structures were introduced to the design of fluid-driven hydrogel actuators to achieve diverse actuation movements, and a facile fabrication strategy based on removable templates and inside-out diffusion-induced in situ hydrogel crosslinking was adopted. As a result, three types of modular cuboid actuator units (CAUs) achieved linear motion, bending, and twisting. Moreover, combinations of multiple CAUs achieved different actuation modes, including actuation decoupling, superposition, and reprogramming. The diverse actuation functionality would enable new possibilities in application fields for hydrogel soft actuators. Several simple application demos, such as grippers for grasping tasks and a multi-way circuit switch, demonstrated their potential for further applications.