RESUMEN

Photocatalytic fixation of nitrogen to ammonia represents an attractive alternative to the Haber-Bosch process under ambient conditions, and the performance can be enhanced by defect engineering of the photocatalysts, in particular, formation of shallow energy levels due to oxygen vacancies that can significantly facilitate the adsorption and activation of nitrogen. This calls for deliberate size engineering of the photocatalysts. In the present study, pyrochlore Bi2Ti2O7 quantum dots and (bulk-like) nanosheets are prepared hydrothermally by using bismuth nitrate and titanium sulfate as the precursors. Despite a similar oxygen vacancy concentration, the quantum dots exhibit a drastically enhanced photocatalytic performance toward nitrogen fixation, at a rate of 332.03 µmol g-1 h-1, which is 77 times higher than that of the nanosheet counterpart. Spectroscopic and computational studies based on density functional theory calculations show that the shallow levels arising from oxygen vacancies in the Bi2Ti2O7 quantum dots, in conjunction with the moderately constrained quantum confinement effect, facilitate the chemical adsorption and activation of nitrogen.

RESUMEN

Photocatalysis represents an effective technology for environmental remediation. Herein, a series of Zn-doped BiOBr hollow microspheres are synthesized via one-pot solvothermal treatment of bismuth nitrate and dodecyl ammonium bromide in ethylene glycol along with a calculated amount of zinc acetate. Whereas the materials morphology and crystal structure remain virtually unchanged upon Zn-doping, the photocatalytic performance toward the degradation of ciprofloxacin is significantly improved under visible light irradiation. This is due to the formation of a unique band structure that facilitates the separation of photogenerated electron-hole pairs, reduced electron-transfer resistance, and enhanced electron mobility and carrier concentration. The best sample consists of a Zn doping amount of 1%, which leads to a 99.2% degradation rate of ciprofloxacin under visible photoirradiation for 30 min. The resulting photocatalysts also exhibit good stability and reusability, and the degradation intermediates exhibit reduced cytotoxicity compared to ciprofloxacin. These results highlight the unique potential of BiOBr-based photocatalysts for environmental remediation.

Asunto(s)

Antibacterianos , Zinc , Antibacterianos/farmacología , Microesferas , Luz , Bismuto/química , Ciprofloxacina , Catálisis

RESUMEN

Infiltration of excessive antibiotics into aquatic ecosystems plays a significant role in antibiotic resistance, a major global health challenge. It is therefore critical to develop effective technologies for their removal. Herein, defect-rich Bi2WO6 nanoparticles are solvothermally prepared via epitaxial growth on pristine Bi2WO6 seed nanocrystals, and the efficiency of the photocatalytic degradation of ciprofloxacin, a common antibiotic, is found to increase markedly from 62.51% to 98.27% under visible photoirradiation for 60 min. This is due to the formation of a large number of structural defects, where the synergistic interactions between grain boundaries and adjacent dislocations and oxygen vacancies lead to an improved separation and migration efficiency of photogenerated carriers and facilitate the adsorption and degradation of ciprofloxacin, as confirmed in experimental and theoretical studies. Results from this work demonstrate the unique potential of defect engineering for enhanced photocatalytic performance, a critical step in removing antibiotic contaminants in aquatic ecosystems.

Asunto(s)

Antibacterianos , Bismuto , Antibacterianos/química , Bismuto/química , Catálisis , Ciprofloxacina/química , Nanopartículas/química , Tungsteno/química , Óxidos

RESUMEN

Electrochemical CO2 reduction (CO2RR) is a prospective but challenging method to decrease the CO2 concentration in the current atmosphere; in particular, the poor selectivity of the target product CO and large overpotentials limit its efficiency. Herein, we propose a top-down route to synthesize Bi single atoms (SAs) anchored by N-doped carbon (NCbox) nanoboxes starting from BiOCl nanoplates as the hard templates. In the CO2RR, the obtained Bi single-atom catalyst possesses remarkably-enhanced catalytic performance, achieving a maximal Faraday efficiency (FE) of 91.7% at -0.6 V, which is much higher than that of NCbox-supported Bi nanoparticles (NPs). Further investigations point out that the enhancement can be attributed to the unique coordination structure of the Bi SAs, as well as the fascinating properties of NCbox that can efficiently promote the electron transfer during the electro-catalysis.

RESUMEN

The paper uses an optimized denoising algorithm, combined with spiral CT coronary angiography (CCTA) in conjunction with carotid ultrasound, serological markers relevance for the assessment of coronary artery disease was analysed early T2DM and coronary heart disease (CHD) in patients with coronary and carotid artery disease to provide diagnostic evidence. Papers selected from January 2017 to December 2019 in hospital diagnosed 95 patients CHD, CHD were divided into three groups (n = 45) and T2DM with CHD group (n depending on whether T2DM disease = 50), were compared coronary arteries, the degree of carotid lesions, high-sensitivity C- reactive protein (hsC-RP) and the difference of FFA. CCTA display, combined with CHD of T2DM in double-vessel coronary artery disease and three main right coronary artery, left circumflex artery plaques appear more CHD combined group of T2DM, and three double-vessel coronary disease carotid plaque compared with the number of single-vessel disease and more. Spearman correlation analysis showed, hsC-RP positively correlated with FFA, hsC-RP and coronary artery lesion count was positively correlated. CCTA display, T2DM with CHD in coronary plaque with soft plaque and mixed plaque mainly extensive coronary artery disease, carotid artery ultrasound prompted the more peripheral vascular plaque number, the more the number of diseased vessels, the more severe the disease. Joint CCTA Clinically, carotid ultrasound and hsC-RP, FFA level detection can improve the rate of diagnosis of T2DM with CHD, reduce false positives, should be widely applied.

RESUMEN

Programmed cell death 1 (PD-1) monoclonal antibodies have been approved by regulatory agencies for the treatment of various types of cancer, and the mechanism involves the restoration of T cell functions. We report herein the X-ray crystal structure of a fully human monoclonal antibody mAb059c fragment antigen-binding (Fab) in complex with the PD-1 extracellular domain (ECD) at a resolution of 1.70 Å. Structural analysis indicates 1) an epitope, comprising fragments from the C'D, BC and FG loops of PD-1, contributes to mAb059c interaction, 2) an unique conformation of the C'D loop and a different orientation of R86 enabling the capture of PD-1 by the antibody complementarity determining region (CDR) and the formation of one salt-bridge contact - ASP101(HCDR3):ARG86(PD-1), and 3) the contact of FG with light chain (LC) CDR3 is maintained by a second salt-bridge and two backbone hydrogen bonds. Interface analysis reveals that N-glycosylation sites 49, 74 and 116 on PD-1 do not contact mAb059c; while N58 in the BC loop is recognized by mAb059c heavy chain CDR1 and CDR2. Mutation of N58 attenuated mAb059c binding to PD-1. These findings and the novel anti-PD-1 antibody will facilitate better understanding of the mechanisms of the molecular recognition of PD-1 receptor by anti-PD-1 mAb and, thereby, enable the development of new therapeutics with an expanded spectrum of efficacy for unmet medical needs.

Asunto(s)

Adenocarcinoma/terapia , Anticuerpos Monoclonales/química , Anticuerpos Monoclonales/uso terapéutico , Antineoplásicos Inmunológicos/química , Antineoplásicos Inmunológicos/uso terapéutico , Neoplasias del Colon/terapia , Receptor de Muerte Celular Programada 1/química , Animales , Afinidad de Anticuerpos , Complejo Antígeno-Anticuerpo/química , Línea Celular Tumoral , Modelos Animales de Enfermedad , Epítopos/química , Técnicas de Sustitución del Gen , Células HEK293 , Humanos , Enlace de Hidrógeno , Fragmentos Fab de Inmunoglobulinas/química , Masculino , Ratones , Ratones Endogámicos C57BL , Ratones Transgénicos , Receptor de Muerte Celular Programada 1/genética , Unión Proteica , Dominios Proteicos , Transfección

RESUMEN

During pregnancy, placental protein-13 (galectin-13) is highly expressed in the placenta and fetal tissue, and less so in maternal serum that is related to pre-eclampsia. To understand galectin-13 function at the molecular level, we solved its crystal structure and discovered that its dimer is stabilized by two disulfide bridges between Cys136 and Cys138 and six hydrogen bonds involving Val135, Val137, and Gln139. Native PAGE and gel filtration demonstrate that this is not a crystallization artifact because dimers also form in solution. Our biochemical studies indicate that galectin-13 ligand binding specificity is different from that of other galectins in that it does not bind ß-galactosides. This is partly explained by the presence of Arg53 rather than His53 at the bottom of the carbohydrate binding site in a position that is crucial for interactions with ß-galactosides. Mutating Arg53 to histidine does not re-establish normal ß-galactoside binding, but rather traps cryoprotectant glycerol molecules within the ligand binding site in crystals of the R53H mutant. Moreover, unlike most other galectins, we also found that GFP-tagged galectin-13 is localized within the nucleus of HeLa and 293 T cells. Overall, galectin-13 appears to be a new type of prototype galectin with distinct properties.

Asunto(s)

Aminoácidos/química , Disacáridos/química , Galectinas/química , Glicerol/química , Monosacáridos/química , Proteínas Gestacionales/química , Aminoácidos/metabolismo , Animales , Sitios de Unión , Núcleo Celular/metabolismo , Núcleo Celular/ultraestructura , Pollos , Cristalografía por Rayos X , Disacáridos/metabolismo , Galactósidos , Galectinas/genética , Galectinas/metabolismo , Expresión Génica , Glicerol/metabolismo , Proteínas Fluorescentes Verdes/genética , Proteínas Fluorescentes Verdes/metabolismo , Células HEK293 , Células HeLa , Pruebas de Hemaglutinación , Humanos , Enlace de Hidrógeno , Modelos Moleculares , Monosacáridos/metabolismo , Mutación , Proteínas Gestacionales/genética , Proteínas Gestacionales/metabolismo , Unión Proteica , Conformación Proteica en Hélice alfa , Conformación Proteica en Lámina beta , Dominios y Motivos de Interacción de Proteínas , Multimerización de Proteína , Proteínas Recombinantes/química , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo

RESUMEN

Galectin-10 (Gal-10) which forms Charcot-Leyden crystals in vivo, is crucial to regulating lymph cell function. Here, we solved the crystal structures of Gal-10 and eight variants at resolutions of 1.55-2.00 Å. Structural analysis and size exclusion chromatography demonstrated that Gal-10 dimerizes with a novel global shape that is different from that of other prototype galectins (e.g., Gal-1, -2 and -7). In the Gal-10 dimer, Glu33 from one subunit modifies the carbohydrate-binding site of another, essentially inhibiting disaccharide binding. Nevertheless, glycerol (and possibly other small hydroxylated molecules) can interact with residues at the ligand binding site, with His53 being the most crucial for binding. Alanine substitution of the conserved Trp residue (Trp72) that is crucial to saccharide binding in other galectins, actually leads to enhanced erythrocyte agglutination, suggesting that Trp72 negatively regulates Gal-10 ligand binding. Overall, our crystallographic and biochemical results provide insight into Gal-10 ligand binding specificity.

Asunto(s)

Carbohidratos/química , Dimerización , Galectinas/química , Sitios de Unión , Galectinas/genética , Galectinas/aislamiento & purificación , Humanos , Ligandos , Modelos Moleculares

RESUMEN

Ethanol extract of Yueju pill, a Traditional Chinese Medicine herbal formula widely used to treat mood disorders, demonstrates rapid antidepressant effects similar to ketamine, likely via instant enhancement of brain-derived neurotrophic factor (BDNF) expression in the hippocampus. Here we investigated ethanol extracts of the constituent herbs of Yueju responsible for rapid antidepressant effects. Screening with tail suspension test in Kunming mice at 24 hours after a single administration of five individual constituent herbs of Yueju, we found that only Gardenia jasminoides Ellis (GJ) showed a significant effect. The antidepressant response started at 2 hours after GJ administration. Similar to Yueju and ketamine, a single administration of GJ significantly reduced the number of escape failures in the learned helplessness test. Furthermore, GJ decreased latency of food consumption in the novelty suppressed-feeding test. Additionally, starting from 2 hours and continuing for over 20 hours after GJ administration, BDNF expression in the hippocampus was upregulated, temporally linked with the antidepressant response. These findings suggest that GJ has rapid antidepressant effects, which are associated with the elevated expression of BDNF in the hippocampus. In Yueju formula, Yue represents GJ, as thus our study demonstrates the primary role of GJ in rapid antidepressant efficacy of Yueju.

RESUMEN

The traditional antidepressants have a major disadvantage in delayed onset of efficacy, and the emerging fast-acting antidepressant ketamine has adverse behavioral and neurotoxic effects. Yueju pill, an herb medicine formulated eight hundred years ago by Doctor Zhu Danxi, has been popularly prescribed in China for alleviation of depression-like symptoms. Although several clinical outcome studies reported the relative short onset of antidepressant effects of Yueju, this has not been scientifically investigated. We, therefore, examined the rapid antidepressant effect of Yueju in mice and tested the underlying molecular mechanisms. We found that acute administration of ethanol extract of Yueju rapidly attenuated depressive-like symptoms in learned helpless paradigm, and the antidepressant-like effects were sustained for at least 24 hours in tail suspension test in ICR mice. Additionally, Yueju, like ketamine, rapidly increased the expression of brain-derived neurotrophic factor (BDNF) in the hippocampus, whereas the BDNF mRNA expression remained unaltered. Yueju rapidly reduced the phosphorylation of eukaryotic elongation factor 2 (eEF2), leading to desuppression of BDNF synthesis. Unlike ketamine, both the BDNF expression and eEF2 phosphorylation were revered at 24 hours after Yueju administration. This study is the first to demonstrate the rapid antidepressant effects of an herb medicine, offering an opportunity to improve therapy of depression.