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Ni, Fe, and Cu foams to form robust binder-free electrodes for high-performance electrocatalytic reactions. [55][56][57][58][59] Interestingly, multidimensional electrocatalysts grown at the nanoscale on a range of current collectors, namely substrates and will benefit from a strong adhesion with the current collector to avoid catalyst delamination, limited active sites, and charge transfer blockage to enhance catalytic reactions (Figure 1b-d). [9,[60][61][62][63][64] Key Prospects, Insights, and the Dynamic Properties of Nano-and Microstructured Binder-Free Electrocatalysts and Their Direct Impact on Electrochemical ReactionsWater splitting has become one of the most important technologies to produce hydrogen (H 2 ) in high purity form. Water splitting includes two half-reactions, namely the cathodic HER and anodic OER. [8,65] Generally, the electrocatalytic performance and activity are highly sensitive to local reaction conditions and is largely valued by the energy required for adsorption/desorption of reaction intermediates and the rupture/creation of chemical bonds. Hence, the conventional powder form of precious metals such as Pt/C for the HER and RuO 2 or IrO 2 for the OER are considered ideal electrocatalysts. [66] In addition, several nonprecious 1D, 2D, and 3D nano-and microstructured powder catalysts such as MoS 2 , WS 2 , Ni 3 S 2 , NiCo 2 S 4 are also of interest for the HER and OER reactions. [54,[67][68][69][70][71][72][73][74] However, for commercial purposes and practical applica-

Background/Aims: Cardiac fibrosis after myocardial infarction (MI) has been identified as a key factor in the development of heart failure, but the mechanisms undelying cardiac fibrosis remained unknown. microRNAs (miRNAs) are novel mechanisms leading to fibrotic diseases, including cardiac fibrosis. Previous studies revealed that miR-22 might be a potential target. However, the roles and mechanisms of miR-22 in cardiac fibrosis remained ill defined. The present study thus addressed the impact of miR-22 in cardiac fibrosis. Methods: After seven days following coronary artery occlusion in mice, tissues used for histology were collected and processed for Masson's Trichrome staining. In addition, cardiac fibroblasts were transfected with mimics and inhibitors of miR-22 using Lipofectamin 2000, and luciferase activity was measured in cell lysates using a luciferase assay kit. Western blotting was used to detect the expression of collagen1, α-SMA and TGFβRI proteins levels, and real time-PCR was employed to measure the Col1α1, Col3α1, miR-22 and TGFβRI mRNA levels. Results: In this study, we found that miR-22 was dynamically downregulated following MI induced by permanent ligation of the left anterior descending coronary artery for 7 days, an effect paralleled by significant collagen deposition. Inhibition of miR-22 with AMO-22 resulted in increased expression of Col1α1, Col3α1 and fibrogenesis in cultured cardiac fibroblasts. Conversely, overexpression of miR-22 in cultured cardiac fibroblasts significantly abrogated angiotensin II-induced collagen formation and fibrogenesis. Furthermore, we found that TGFβRI is a direct target for miR-22, and downregulation of TGFβR may have mediated the antifibrotic effect of miR-22. Conclusion: Our data clearly demonstrate that miR-22 acts as a novel negative regulator of angiotensin II-induced cardiac fibrosis by suppressing the expression of TGFβRI in the heart and may represent a new potential therapeutic target for treating cardiac fibrosis.

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Rechargeable zinc-air batteries (ZABs) are a promising energy conversion device, which rely critically on electrocatalysts to accelerate their rate-determining reactions such as oxygen reduction (ORR) and oxygen evolution reactions (OER). Herein, we fabricate a range of bifunctional M–N–C (metal-nitrogen-carbon) catalysts containing M–Nx coordination sites and M/MxC nanoparticles (M = Co, Fe, and Cu) using a new class of γ-cyclodextrin (CD) based metal–organic framework as the precursor. With the two types of active sites interacting with each other in the catalysts, the obtained Fe@C-FeNC and Co@C-CoNC display superior alkaline ORR activity in terms of low half-wave (E1/2) potential (~ 0.917 and 0.906 V, respectively), which are higher than Cu@C-CuNC (~ 0.829 V) and the commercial Pt/C (~ 0.861 V). As a bifunctional electrocatalyst, the Co@C-CoNC exhibits the best performance, showing a bifunctional ORR/OER overpotential (ΔE) of ~ 0.732 V, which is much lower than that of Fe@C-FeNC (~ 0.831 V) and Cu@C-CuNC (~ 1.411 V), as well as most of the robust bifunctional electrocatalysts reported to date. Synchrotron X-ray absorption spectroscopy and density functional theory simulations reveal that the strong electronic correlation between metallic Co nanoparticles and the atomic Co-N4 sites in the Co@C-CoNC catalyst can increase the d-electron density near the Fermi level and thus effectively optimize the adsorption/desorption of intermediates in ORR/OER, resulting in an enhanced bifunctional electrocatalytic performance. The Co@C-CoNC-based rechargeable ZAB exhibited a maximum power density of 162.80 mW cm−2 at 270.30 mA cm−2, higher than the combination of commercial Pt/C + RuO2 (~ 158.90 mW cm−2 at 265.80 mA cm−2) catalysts. During the galvanostatic discharge at 10 mA cm−2, the ZAB delivered an almost stable discharge voltage of 1.2 V for ~ 140 h, signifying the virtue of excellent bifunctional ORR/OER electrocatalytic activity.