Preparation of recyclable magnetic palladium nanocatalysts by dispersion strategy based on sodium alginate for reduction of p-nitrophenol and Suzuki-Miyaura coupling.

Palladium (Pd) has excellent catalytic performance, its application is seriously limited by low atomic utilization and weak recovery capacity. To solve these problems, we report a universal palladium nanocatalysts preparation strategy by taking advantage of the rich chemistry of sodium alginate (SA). SA units not only self-assemble into a cross-linked porous carboxyl and hydroxyl framework but also can coat different substrates. Benefiting from the distinguished chelation of SA, metallic nanocatalysts can be achieved. As a proof-of-concept demonstration, Pd loading on nano-Fe3O4 modified with SA and investigated their catalytic capabilities. The catalyst was Fe3O4 nanoparticles encapsulated by SA film loaded with 0.4 wt% of Pd. It has a particle size around 100 nm and has good superparamagnetism with a saturation strength of 76.26 emu/g. It exhibited good catalytic activity at TOF = 660 h-1 and TOF = 4311 h-1 in typical Suzuki-Miyaura coupling reaction and the reduction of p-nitrophenol, respectively, and showed appreciable recyclability in the test of recyclability. Thus, our findings demonstrate that recyclable magnetic palladium nanocatalysts have several attractive features, such as easy preparation, outstanding catalytic activity and reusability. This work lays the foundation for the preparation of palladium nanocatalysts and the potential application of SA in the field of catalysts.

Midterm Outcome of Valve Repair for Rheumatic Mitral Stenosis: 6-year Experience in a Single Mid-Volume Cardiac Center.

OBJECTIVES: Previous studies have reported satisfactory long-term results of mitral valve (MV) repair for rheumatic mitral disease. However, the effects of this procedure in isolated rheumatic mitral stenosis remain unclear. In addition, protective effects of MV repair on cardiac function have not been verified in rheumatic MV disease. This study retrospectively evaluated early mortality and mid-term results of MV repair for isolated rheumatic mitral stenosis in a mid-volume cardiac centre, and explored the effects of this procedure on cardiac function. METHODS: Between January 2015 and May 2021, 360 patients with isolated rheumatic mitral stenosis and combined (concomitant) atrial fibrillation (AF) underwent MV repair (100 patients) or MV replacement (260 patients). Perioperative characteristics were compared between the two groups and a regression analysis for early mortality and mid-term left ventricular ejection fraction was conducted. In addition, mid-term survival was compared between the two groups. RESULTS: Baseline characteristics of the two groups were balanced after matching. Compared with patients in the replacement group, patients with MV repair had a lower occurrence of postoperative hypotension and AF. There was no difference in early mortality or mid-term survival between the two groups. However, MV repair was associated with a higher mid-term left ventricular ejection fraction. During follow-up, four thromboembolic events and four haemorrhagic events occurred in the replacement group. No blood coagulation-related complications occurred in the repair group. CONCLUSION: Mitral valve repair for isolated rheumatic mitral stenosis and concomitant AF was feasible in a mid-volume cardiac centre, with satisfactory perioperative results and mid-term outcomes. Furthermore, this procedure preserved mid-term left ventricular systolic function.

Chitosan Hydrogel Enhances the Therapeutic Efficacy of Bone Marrow-Derived Mesenchymal Stem Cells for Myocardial Infarction by Alleviating Vascular Endothelial Cell Pyroptosis.

Myocardial infarction (MI) is one of the higher mortality rates, and current treatment can only delay the progression of the disease. Experiments have shown that cell therapy could improve cardiac function and mesenchymal stem cells (MSCs)-based therapies provide a great promising approach in the treatment of MI. However, low cell survival and engraftment restricts the successful application of MSCs for treating MI. Here, we explored whether co-transplantation of a chitosan (CS) thermosensitive hydrogel with bone marrow-derived MSCs (BMSCs) could optimize and maximize the therapeutic of BMSCs in a mouse model of MI. The fate of transplanted BMSCs was monitored by bioluminescence imaging, and the recovery of cardiac function was detected by echocardiogram. Our results proved that CS hydrogel enhanced the BMSCs' survival and the recovery of cardiac function by protecting the vascular endothelial cells. Further studies revealed that the increased number of vascular endothelial cells was due to the fact that transplanted BMSCs inhibited the inflammatory response and alleviated the pyroptosis of vascular endothelial cells. In conclusions, CS hydrogel improved the engraftment of transplanted BMSCs, ameliorated inflammatory responses, and further promoted functional recovery of heart by alleviating vascular endothelial cell pyroptosis.