Interface Engineering of Zinc Electrode for Rechargeable Alkaline Zinc-Based Batteries.

Rechargeable aqueous zinc-based batteries have gained considerable interest because of their advantages of high theoretical capacity, being eco-friendly, and cost effectiveness. In particular, zinc-based batteries with alkaline electrolyte show great promise due to their high working voltage. However, there remain great challenges for the commercialization of the rechargeable alkaline zinc-based batteries, which are mainly impeded by the limited reversibility of the zinc electrode. The critical problems refer to the dendrites growth, electrode passivation, shape change, and side reactions, affecting discharge capacity, columbic efficiency, and cycling stability of the battery. All the issues are highly associated with the interfacial properties, including both electrons and ions transport behavior at the electrode interface. Herein, this work concentrates on the fundamental electrochemistry of the challenges in the zinc electrode and the design strategies for developing high-performance zinc electrodes with regard to optimizing the interfaces between host and active materials as well as electrode and electrolyte. In addition, potential directions for the investigation of electrodes and electrolytes for high-performance zinc-based batteries are presented, aiming at promoting the development of rechargeable alkaline zinc-based batteries.

Fabrication of Robust, Shape Recoverable, Macroporous Bacterial Cellulose Scaffolds for Cartilage Tissue Engineering.

Recently, the fabricating of three-dimensional (3D) macroporous bacterial cellulose (MP-BC) scaffolds with mechanically disintegrated BC fragments has attracted considerable attention. However, the successful implementation of these materials depends mainly on their mechanical stability and robustness. Here, a non-toxic crosslinker, 1-ethyl-3-(-3-dimethylaminopropyl) carbodiimide hydrochloride/N-hydroxysuccinimide (EDC/NHS), is employed to induce crosslinking reactions between BC fragments. In addition to their large pore sizes, the EDC/NHS-crosslinked MP-BC scaffolds exhibit excellent compression properties and shape recovery ability, owing to the EDC/NHS-induced crosslinking on the BC nanofibers. The results of in vitro studies reveal that the biocompatibility of MP-BC scaffolds is better than that of pristine BC scaffolds because the former provided more space for cell proliferation. The results of in vivo studies show that the neocartilage tissue with native cartilage appearance and abundant cartilage-specific extracellular matrix deposition is successfully regenerated in nude mice. The findings reveal the immense application potential of mechanically robust BC scaffolds with controllable pore sizes and shape-recoverable properties in tissue engineering.

Simultaneous engineering of nanofillers and patterned surface macropores of graphene/hydroxyapatite/polyetheretherketone ternary composites for potential bone implants.

Incorporating bioactive nanofillers and creating porous surfaces are two common strategies used to improve the tissue integration of polyetheretherketone (PEEK) material. However, few studies have reported the combined use of both strategies to modify PEEK. Herein, for the first time, dual nanoparticles of graphene oxide (GO) and hydroxyapatite (HAp) were incorporated into PEEK matrix to obtain ternary composites that were laser machined to create macropores with diameters ranging from 200 µm to 600 µm on the surfaces. The surface morphology and chemistry, mechanical properties, and cellular responses of the composites were investigated. The results show that micropatterned pores with a depth of 50 µm were created on the surfaces of the composites, which do not significantly affect the mechanical properties of the resultant composites. More importantly, the incorporation of GO and HAp significantly improves the cell adhesion and proliferation on the surface of PEEK. Compared to the smooth surface composite, the composites with macroporous surface exhibit markedly enhanced cell viability. The combined use of nanofillers and surface macropores may be a promising way of improving tissue integration of PEEK for bone implants.

Heparinization and hybridization of electrospun tubular graft for improved endothelialization and anticoagulation.

Constructing biomimetic structure and immobilizing antithrombus factors are two effective methods to ensure rapid endothelialization and long-term anticoagulation for small-diameter vascular grafts. However, few literatures are available regarding simultaneous implementation of these two strategies. Herein, a nano-micro-fibrous biomimetic graft with a heparin coating was prepared via a step-by-step in situ biosynthesis method to improve potential endothelialization and anticoagulation. The 4-mm-diameter tubular graft consists of electrospun cellulose acetate (CA) microfibers and entangled bacterial nanocellulose (BNC) nanofibers with heparin coating on dual fibers. The hybridized and heparinized graft possesses suitable pore structure that facilitates endothelia cells adhesion and proliferation but prevents infiltration of fibrous tissue and blood leakage. In addition, it shows higher mechanical properties than those of bare CA and hybridized CA/BNC grafts, which match well with native blood vessels. Moreover, this dually modified graft exhibits improved blood compatibility and endothelialization over the counterparts without hybridization or heparinization according to the testing results of platelet adhesion, cell morphology, and protein expression of von Willebrand Factor. This novel graft with dual modifications shows promising as a new small-diameter vascular graft. This study provides a guidance for promoting endothelialization and blood compatibility by dual modifications of biomimetic structure and immobilized bioactive molecules.

Biomimetic Bacterial Cellulose-Enhanced Double-Network Hydrogel with Excellent Mechanical Properties Applied for the Osteochondral Defect Repair.

Although hydrogels based on biopolymers show many advantages, their low mechanical properties limit their applications in osteochondral tissue engineering. In this study, one part of our work aimed at preparing a high strength biohydrogel by using a double-network (DN) hydrogel system, which consisted of two interpenetrating polymer networks composed of γ-glutamic acid, lysine, and alginate, and meanwhile by incorporating bacterial cellulose into the DN structures. The results showed that compression modulus of the resultant hydrogel (0.322 MPa) was comparable with that of natural articular cartilage and swelling degree was greatly depressed by using these strategies. On this basis, a bilayer hydrogel scaffold based on the bionics principle for osteochondral regeneration was fabricated via chemical and physical cross-linking. Additionally, hydroxyapatite (HA) particles with two different sizes were introduced into the bilayer hydrogels, respectively: micro-HA in the top layer for promoting cartilage matrix deposition and HA nanocrystals in the bottom layer for enhancing compression modulus and osteogenesis. The osteochondral defect model of rabbits was used to evaluate the repair effect of the scaffolds with the bilayer structure, and the results showed such as-synthesized scaffolds had a good osteochondral repair effect.