Antibacterial hydrogel has received extensive attention in soft tissue repair, especially preventing infections those associated with impaired wound healing. However, it is challenging in developing an inherent antibacterial hydrogel integrating with excellent cell affinity and superior mechanical properties. Inspired by the mussel adhesion chemistry, a contact-active antibacterial hydrogel is proposed by copolymerization of methacrylamide dopamine (MADA) and 2-(dimethylamino)ethyl methacrylate and forming an interpenetrated network with quaternized chitosan. The reactive catechol groups of MADA endow the hydrogel with contact intensified bactericidal activity, because it increases the exposure of bacterial cells to the positively charged groups of the hydrogel and strengthens the bactericidal effect. MADA also maintains the good adhesion of fibroblasts to the hydrogel. Moreover, the hybrid chemical and physical cross-links inner the hydrogel network makes the hydrogel strong and tough with good recoverability. In vitro and in vivo tests demonstrate that this tough and contact-active antibacterial hydrogel is a promising material to fulfill the dual functions of promoting tissue regeneration and preventing bacterial infection for wound-healing applications.
This article provides an overview of solution-based methods for the controllable synthesis of metal oxides and their applications for electrochemical energy storage. Typical solution synthesis strategies are summarized and the detailed chemical reactions are elaborated for several common nanostructured transition metal oxides and their composites. The merits and demerits of these synthesis methods and some important considerations are discussed in association with their electrochemical performance. We also propose the basic guideline for designing advanced nanostructure electrode materials, and the future research trend in the development of high power and energy density electrochemical energy storage devices.
High‐energy Li‐rich layered cathode materials (≈900 Wh kg−1) suffer from severe capacity and voltage decay during cycling, which is associated with layered‐to‐spinel phase transition and oxygen redox reaction. Current efforts mainly focus on surface modification to suppress this unwanted structural transformation. However, the true challenge probably originates from the continuous oxygen release upon charging. Here, the usage of dielectric polarization in surface coating to suppress the oxygen evolution of Li‐rich material is reported, using Mg2TiO4 as a proof‐of‐concept material. The creation of a reverse electric field in surface layers effectively restrains the outward migration of bulk oxygen anions. Meanwhile, high oxygen‐affinity elements of Mg and Ti well stabilize the surface oxygen of Li‐rich material via enhancing the energy barrier for oxygen release reaction, verified by density functional theory simulation. Benefited from these, the modified Li‐rich electrode exhibits an impressive cyclability with a high capacity retention of ≈81% even after 700 cycles at 2 C (≈0.5 A g−1), far superior to ≈44% of the unmodified counterpart. In addition, Mg2TiO4 coating greatly mitigates the voltage decay of Li‐rich material with the degradation rate reduced by ≈65%. This work proposes new insights into manipulating surface chemistry of electrode materials to control oxygen activity for high‐energy‐density rechargeable batteries.
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