Visible-Light-Mediated Nano-biomineralization of Customizable Tough Hydrogels for Biomimetic Tissue Engineering

Biomineralized tough hydrogels (BTHs) have advanced applications in the fields of soft bioelectronics and biomimetic tissue engineering. But the development of rapid and general photomineralization strategies for one-step fabrication of customizable BTHs is still a challenging task. Here we report a straightforward, low-cost visible-light-mediated nano-biomineralization (VLMNB) strategy via a rational design of a phosphate source and efficient ruthenium photochemistry. Multinetwork tough hydrogels are simultaneously constructed under the same condition. Therefore, BTHs are rapidly prepared in a short time as low as ∼60 s under visible light irradiation. The in situ formation of calcium phosphate particles can improve BTHs' mechanical and biological properties and reduce the friction coefficient with bones. Furthermore, fast biomineralization and solidification processes in these BTHs benefit their injectable and highly flexible customizable design, showing applications of promoting customizable skin repair and bone regeneration.

Dopamine/zinc oxide doped poly(N-hydroxyethyl acrylamide)/agar dual network hydrogel with super self-healing, antibacterial and tissue adhesion functions designed for transdermal patch

Dual network (DN) hydrogels with excellent mechanical strength and controllable component adjustment characteristics have a broad application range in the field of biomedicine. However, the tissue adhesion, skin affinity, self-healing, and antibacterial properties of DN hydrogels are inadequate for their application as skin patches. In this work, we prepared dopamine/zinc oxide (DOPA/ZnO) doped poly(N-hydroxyethyl acrylamide) (p(HEAA))/agar DN hydrogels and combined them to obtain a bilayer hydrogel (two-layer gel) with moisturizing properties. Upon incorporating 0.86 wt% of dopamine (DOPA), the resultant DOPA/p(HEAA))/agar DN hydrogel (DOPA@DNG) exhibited high tensile strain (up to 1600%), excellent self-repair ability, and tissue adhesion. ZnO/p(HEAA))/agar DN hydrogel (ZnO NG) obtained by incorporating 2 w/v ZnO nanoparticles (ZnO NPs) achieved high tensile strength (1.2 MPa), good antibacterial ability, and low charge transfer resistance. Moreover, ZnO NG, which has a tight structure, was employed as a protective layer for the two-layer gel, which can effectively slow down the excessive evaporation of water to protect the DOPA@DNG stability as a skin patch. Evidence showed that the two-layer hydrogel has water retention. Water retention still remains at over 50% after keeping the hydrogel in air for 3 days. These properties mean the two-layer gel based on the DOPA/ZnO doped DN hydrogels could be used as a transdermal patch for numerous applications in drug delivery, wearable devices, and electronic skin.

Surface Modification of Reduced Graphene Oxide Beads: Integrating Efficient Endotoxin Adsorption and Improved Blood Compatibility

As a pathogenic toxin, endotoxins are the culprit for endotoxemia and can be generally removed from the blood by hemoperfusion. Reduced graphene oxide (rGO) is a promising endotoxin sorbent for hemoperfusion owing to its excellent adsorption capacity, but it has the side effect of nonspecific adsorption and low blood compatibility. Polymyxin B (PMB) acts as an organic affinity ligand that can specifically bind endotoxins. As a natural anticoagulant, heparin (Hep) can reduce the risk of coagulation and improve the blood compatibility of materials. Herein, an rGO bead adsorbent was prepared by coupling with PMB and Hep and used for endotoxin adsorption; in this, polydopamine (pDA) served as an active coating for immobilization of PMB and further coupling with Hep. The physicochemical characteristics indicated that PMB and Hep were successfully immobilized on rGO beads with a hierarchical pore structure. PMB endowed rGO beads with higher adsorption capacity (143.84 ± 3.28 EU/mg) and good adsorption selectivity for endotoxins. Hep significantly improved the blood compatibility of rGO beads. These modified rGO beads also achieved good adsorption capacity and adsorption selectivity for endotoxins in plasma, serum, or blood. Therefore, rGO/pDA/PMB/Hep beads are potential adsorbents for endotoxins in hemoperfusion.