Xiao-Hui Wang,Yue-Han Qin,Xue Xiao,Yu Chen,Shu-Ni Li
Histidine-functionalized Cu 2 O effectively stabilizes Cu + species under cathodic conditions. • The histidine functionalization enhances the co-adsorption of *CO and *NO x intermediates. • The formation of an interfacial hydrogen-bond network on the catalyst surface accelerates proton transfer kinetics. • The histidine-functionalized Cu 2 O catalyst achieves a high urea Faradaic efficiency alongside a notably high yield rate. Electrocatalytic C-N coupling for urea synthesis from CO 2 and nitrate (NO 3 - ) offers a sustainable alternative to the energy-intensive industrial process. Copper (Cu)-based catalysts are uniquely capable of activating both CO 2 and NO 3 - ; however, the catalytically active Cu + species is prone to over-reduction to Cu 0 under cathodic conditions, leading to poor selectivity and instability. Herein, we report a histidine-functionalized Cu 2 O nanospheres (His-Cu 2 O NSs) that stabilize Cu + under operating conditions. The preserved Cu + electronic structure promotes synchronized adsorption of *CO and *NO x intermediates, while protonated amino groups construct a hydrogen-bonded interfacial water network that accelerates proton transfer. As a result, the optimized catalyst achieves a urea Faradaic efficiency of 42.3% and a yield rate of 41.9 mmol h −1 g −1 at −1.1 V potential, with exceptional stability over 100 h in both H-type and flow cells. In situ spectroscopy and density functional theory calculations reveal that histidine coordination not only enhances *CO adsorption but also lowers the energy barrier for C-N coupling, thereby accelerating C-N bond formation. Meanwhile, the in-situ EXAFS results indicate that Cu + species can effectively be retained after histidine modification. This work establishes a molecular-level design principle for regulating complex multi-reactant electrocatalysis and provides a versatile strategy for promoting efficient C-N coupling reactions. Download: Download high-res image (156KB) Download: Download full-size image Functionalizing Cu 2 O nanospheres establishes a generalizable stabilization-via-delocalization principle providing a blueprint for designing durable organic-inorganic interfaces for electrocatalytic urea synthesis.
Metabolites in the body fluid are becoming a rich source of disease biomarkers. Developing an effective and high throughput detection and analysis platform of metabolites is of great importance for potential biomarker discovery and validation. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) has been successfully applied in rapid biomolecules detection in large scale. However, non-negligible background interference in low molecule-weight region still constitutes a main challenge even though various nanomaterials have been developed as an alternative to traditional organic matrix. In this work, a novel composite chip, silicon nanowires loaded with fluorinated ethylene propylene (FEP@SiNWs) was fabricated. It can serve as an excellent substrate for nanostructure-initiator mass spectrometry (NIMS) detection with ultra-low background noise in low molecular weight region (<500 Da). Ion desorption efficiency and internal energy transfer of FEP@SiNWs were studied using benzylpyridinium salt and tetraphenylboron salt as thermometer chemicals. The results indicated that a non-thermal desorption mechanism might be involved in the LDI process on FEP@SiNWs. Owing to the higher LDI efficiency and low background interference of this novel substrate, the metabolic fingerprint of complex bio-fluids, such as human saliva, can be sensitively and stably acquired. As a proof of concept, FEP@SiNWs chip was successfully used in the detection of salivary metabolites. With the assistance of multivariate analysis, 22 metabolic candidates (p < 0.05) which can discriminate type 2 diabetes mellitus (2-DM) and healthy volunteers were found and identified. The role of these feature metabolites in the metabolic pathway involved in 2-DM was confirmed by literature mining. This work demonstrates that FEP@SiNWs-based NIMS might be served as an efficient and high throughput platform for metabolic biomarker exploration and clinical diagnosis.
Angelica dahurica radix (ADR), the root of the botanical family Apiaceae (genus Angelica , species Angelica dahurica ( Hoffm .)), has been used to treat colitis in clinical practice. The immunomodulatory effects of ADR are attributed to its polysaccharides (RP). However, its mechanism of action has not been elucidated. In this study, RP's structure was determined through nuclear magnetic resonance analysis. Dextran sulfate sodium-induced colitis in mice was utilized to assess the therapeutic efficacy of RP, while experiments involving fecal microbiota transplantation (FMT) and antibiotic treatment were performed to investigate the contribution of gut microbiota to RP's protective function. Non-targeted metabolomics was utilized to identify potential targets for elucidating the underlying mechanisms. RP is likely composed of (→4)-α-D-Glcp-(1→ and →4)-α-D-Galp-(1→). It effectively alleviated DSS-induced colitis by restoring the balance of the gut microbial community, a finding validated through FMT and antibiotic intervention experiments. Imidazole propionate (ImP) emerged as a potential target for RP's efficacy in treating colitis, which inhibits the activation of peroxisome proliferator-activated receptor gamma (PPAR-γ). Our findings suggest that RP may confer protection against colitis by activating the PPAR-γ signaling pathway through alleviating the constraint imposed by ImP.
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