No abstract

Vascularization of thick hydrogel scaffolds is still a big challenge, because the submicron- or nano-sized pores seriously restrict endothelial cells adhesion, proliferation and migration. Therefore, porous hydrogels have been fabricated as a kind of promising hydrous scaffolds for enhancing vascularization during tissue repairing. In order to investigate the effects of pore size on vascularization, macroporous methacrylated hyaluronic acid (HAMA) hydrogels with different pore sizes were fabricated by a gelatin microspheres (GMS) template method. After leaching out GMS templates, uniform and highly interconnected macropores were formed in hydrogels, which provided an ideal physical microenvironment to induce human umbilical vein endothelial cells (HUVECs) migration and tissue vascularization. In vitro results revealed that macroporous hydrogels facilitated cells proliferation and migration compared with non-macroporous hydrogels. Hydrogels with middle pore size of 200-250 μm (HAMA250 hydrogels) supported the best cell proliferation and furthest 3D migration of HUVECs. The influences of pore sizes on vascularization were then evaluated with subcutaneous embedding. In vivo results illustrated that HAMA250 hydrogels exhibited optimum vascularization behavior. Highest number of newly formed blood vessels and expression of CD31 could be found in HAMA250 hydrogels rather than in other hydrogels. In summary, our results concluded that the best pore size for endothelial cells migration and tissue vascularization was 200-250 μm. This research provides a new insight into the engineering vascularized tissues and may find utility in designing regenerative biomaterial scaffolds

Infection and chronic inflammation caused by oxidative stress are the main challenges in chronic wound healing. In this study, a silk fibroin/kappa‐carrageenan (kCA)‐based hydrogel functionalized with epigallocatechin‐3‐gallate (EGCG) and Cu2+ is fabricated for chronic wound healing. Polyphenol–metal functional complexes and ionic‐covalent entanglement networks are prepared by introducing Cu2+. Cu2+ coordinates with kCA to enhance the mechanical properties and chelates with EGCG to form an EGCG‐Cu2+ complex that continuously releases EGCG. The sustained release of EGCG enhances the antibacterial properties by synergizing with the effects of Cu2+. Furthermore, the prepared hydrogel exhibits a potent ability to scavenge excessive intracellular reactive oxygen species, controllable antioxidant bioactivity, and reliable biocompatibility. Ultimately, the resulting multifunctional hydrogel dressing provides a potential and effective strategy for chronic wound care management with increased mechanical strength and antibacterial and antioxidant properties.

In this work, a double network bovine serum albumin-polyacrylamide (BSA-PAM) adhesive hydrogel was fabricated, in which combination of physical interactions including hydrogen bonds and chain entanglements, and chemical covalent photo-crosslinking. The BSA-PAM hydrogel exhibited excellent mechanical and adhesive properties. The composite hydrogel not only demonstrated excellent tensile properties (maximum force elongation 1552%~2037%), but also displayed extremely high fatigue resistance even when subjected to compress strains of up to 85%. More importantly, the BSA-PAM hydrogel showed excellent adhesiveness to various substrates (90 kPa~150 kPa for glass and 9.74 kPa~35.09 kPa for pigskin). This work provided a facile way of fabricating tough, stretchable and adhesive BSA-PAM hydrogels.

Conductive hydrogels used as electronics have received much attention due to their great flexibility and stretchability. However, the fabrication of ideal conductive hydrogels fulfilling the excellent mechanical properties and outstanding sensitivity remains a great challenge until now. Moreover, high sensitivity and broad linearity range are pivotal for the feasibility and accuracy of hydrogel sensors. In this study, a conductive supramolecular hydrogel is engineered by directly mixing the aqueous dispersion of MXene with the precursor of N‐acryloyl glycinamide (NAGA) monomer and then rapidly photo cross‐linked by UV irradiation. The resultant PNAGA/MXene hydrogel‐sensors exhibit high mechanical strength (4.8 MPa), great stretchability (630%), and excellent durability. The conductive hydrogel‐based sensor presents excellent conductivity (17.3 S m−1) and a wide scope of linear dependence of sensitivity on strain (0%–125%, gauge factor = 2.05). It displays reliable detection of various motions, including repeated subtle movements and large strain. It also shows good degradation in vitro and antifouling capability. This work may provide a simple and promising platform for engineering conductive supramolecular hydrogels with integrated high performance aiming for smart wearable electronics, electronic skin, soft robots, and human–machine interfacing.