Latest ArticlesMesoporous carbon supported with transition metals nanoparticles performs desired activities for oxygen reduction reaction (ORR) and clean energy conversion devices such as Zn–air batteries. In this work, we synthesized N-doped mesoporous carbon loaded with cobalt nanoparticles (CoMCN) through self-assembly method. There are sufficient mesopores on the carbon substrate which stem from the pore-forming agent. These mesopores can provide enough accessible active sites and profitable charge/mass transport for ORR. The high content of pyridinic and graphitic N is beneficial for promoting O2 adsorption and reduction. The smaller value of ID/IG indicates the higher degree of graphitization of CoMCN, providing better electronic conductivity. The half-wave potential of CoMCN is 0.865 V in basic solution, which is 24 mV more positive than that of the commercial Pt/C (0.841 V). In addition, CoMCN performs excellent methanol tolerance and stability under both basic and acidic conditions. The Zn–air battery assembled with CoMCN performs the larger power density and open-circuit voltage than the commercial Pt/C-based battery, indicating the potential application in energy conversion systems. This work provides thoughtful ideas for fabricating transition metal nanoparticles based porous carbon for electrocatalysis and metal–air batteries.
Artificial photosynthesis of valuable chemicals from CO2 is a potential way to achieve sustainable carbon cycle. The CO2 conversion activity is still inhibited by the sluggish charge kinetics and poor CO2 activation. Herein, Ag nanoparticles coupled BiOBr have been constructed by in-situ photoreduction strategy. The crafting of interface between Ag nanoparticles and BiOBr nanosheets, achieving an ultra-fast charge transfer. The BiOBr semiconductor excited electrons and plasmonic Ag nanoparticles generated high-energy hot electrons synchronous accelerates the C=O double bond activation. Thus, the optimized Ag/BiOBr-2 heterostructure shows excellent CO2 photoreduction activity with CO production of 133.75 and 6.83 µmol/g under 5 h of 300 W Xe lamp and visible light (λ > 400 nm) irradiation, which is 1.51 and 2.81 folds versus the pristine BiOBr, respectively. The mechanism of CO2 photoreduction was in-depth understood through in-situ FT-IR spectrum and density functional theory calculations. This study provides some new perspectives into efficient photocatalytic CO2 reduction.
Inhibiting the side reactions while promoting hydrogenation are the main target for the production of functional anilines from nitroarenes; consequently, the preparation of an ideal catalyst to improve chemical selectivity is one of the hot issues. In this work, we provided an easy-to-prepare catalyst with N-doped carbon layers, where the FexOy nanoparticles were encapsulated and distributed uniformly. The structural features of catalyst were characterized by several techniques, and the selected catalyst was next applied to the hydrogenation of nitrobenzene under varied conditions, involving temperature, holding period and H2 pressure. Subsequently, we conducted the synthesis of more than 16 substrates for the corresponding anilines with varied functional groups. The hydrogenation protocol to gram-scale synthesis as well as lifecycle performance were also demonstrated in the batch reactor, together with the explanation of its catalytic mechanisms. Overall, the present work provides an available preparation of simple but highly efficient catalysts for the production or aromatic amines, which will be benefit for the sustainable development of this field in near future.
As one of the top global health problems, the effective treatment of cancer is one of the most urgent clinical challenges. Currently, the main treatments for cancer include surgery, chemotherapy, radiotherapy, and gene therapy etc. Chemotherapy is one of the most commonly used treatments, however it has limitations such as highly toxic side effects and low drug utilization rate that limit its application. Gene therapy, as an emerging cancer treatment, has limitations such as drug instability, off-target effects and low internalization efficiency. Poly(amino acid)s carriers with good biocompatibility, degradability and multifunctionality as drug carriers have received much attention, as they can reduce the toxic side effects of chemotherapy, improve drug utilization, and enhance the internalization efficiency and utilization of gene drugs. However, little attention has been paid to the nature of the carriers themselves. This paper reviews the immunomodulatory, anti-inflammatory, antioxidant, internalization-promoting and apoptosis-promoting functions of poly(amino acid)s drug carriers in tumor therapy to provide a theoretical basis for different carrier-drug-adapted synergistic therapies.
The application of fluorescent probes for in vivo retinal imaging is of great importance, which could provide direct and crucial imaging evidence for a better understanding of common eye diseases. Herein, a group of bright organic luminogens with typical electron-donating (D) and electron-accepting (A) structures (abbreviated as LDs-BDM, LDs-BTM, and LDs-BHM) was synthesized through a simple single-step reaction. They were found to be efficient solid-state emitters with high fluorescence quantum yields of above 70% (e.g., 83.7% for LDs-BTM). Their light-emission properties could be tuned by the modulation of π-conjugation effect with methoxy groups at different substituent positions. Their resulting fluorescent nanoparticles (NPs) were demonstrated as specific lipid droplets (LDs) targeting probes with high brightness, good biocompatibility, and satisfactory photostability. LDs-BTM NPs with a large two-photon absorption cross section (σ2 = 249 GM) were further utilized as ultrabright two-photon fluorescence (2PF) nanoprobes for in vivo retina imaging of live zebrafish by NIR excitation at an ultralow concentration (0.5 µmol/L). Integrated histological structures at the tissue level and corresponding fine details at the cellular level of the embryonic retina of live zebrafish were clearly demonstrated. This is the first report of using ultrabright LDs-targeting nanoprobes to accurately measure fine details in the retina with 2PF microscopic technique. These good results are anticipated to open up a new avenue in the development of efficient 2PF emitters for non-invasive bioimaging of living animals.
Bacterial antimicrobial resistance (AMR) is a severe threat to global health and development. Under the stimulation of antibiotics, bacterial cells can undergo filamentation and generate daughter cells with stronger AMR. The current research on bacterial AMR mechanism is mainly conducted with a population of cells. However, bacterial cells exhibit heteroresistance, making the study at population level not reliable. Herein, we developed single bacterial cell metabolic profiling by mass spectrometry (MS) to study bacterial AMR at single-cell level. By utilizing a microprobe controlled by a microoperation platform, single filamentous extended spectrum beta-lactamase (ESBL) producing Escherichia coli (ESBL-E. coli) cells generated by ceftriaxone sodium stimulation can be extracted and spray-ionized for MS analysis. Heterogeneous among ESBL-E. coli cells under the same antibiotic stimulus condition was observed from mass spectra as well as cell morphology. The metabolic profiles by MS of different individual cells can be clustered into subgroups well in accordance with bacterial cell length. Metabolic pathways including arginine and proline metabolism, as well as cysteine and methionine metabolism were disclosed to play an important role in the bacterial SOS-associated filamentation against antibiotics. The microprobe electrospray ionization-MS-based single bacterial cell analysis method is promising in the study of various bacterial AMR mechanism and can reveal the heterogeneity of bacterial AMR from-cell-to-cell.
Cardiovascular disease (CVD) is a global health problem and is thought to be responsible for almost half of all deaths in the world. Nevertheless, currently available diagnostic methods for CVD are strongly depended on clinical observation and monitoring, which commonly result in false diagnosis. Herein, an attractive strategy of a metal-organic framework (MOF) nanofilm-based laser desorption/ionization mass spectrometry (LDI-MS) was developed for enhancing serum metabolic profiling, which could provide precise diagnosis and molecular subtyping of CVD. The porous MOF nanofilm fabricated on indium-tin oxide (ITO) glass possessed enhanced ionization efficiency and size-exclusion effect, which endowed it as substrate with high sensitivity and selectivity for serum metabolites. Furthermore, the MOF nanofilm with uniform surface and high orientation provided high-quality and high-reproducibility serum metabolic profiles (SMPs) without any tedious pretreatment. Further analysis of extracted serum metabolic fingerprints could successfully distinguish patients with CVD from healthy controls and also differentiate two major subtypes of CVD. This work not only extends the application of MOF nanofilm as an attractive MS probe, but also provide an alternative way for precise diagnosis of CVD in molecular level.
Developing efficient photosensitizers for C–P bond construction is highly important and remains a challenge due to the urgently needed for the synthesis of modified nucleosides, nucleotides, and other phosphine-containing ligands. Herein, two pyrene-tethered bismoviologen derivatives (Py-BiV2+) were designed and synthesized for visible-light-induced C–P bonds formation. The photochemical and electrochemical properties of Py-BiV2+ were studied systemically, certifying fine-tunable opto-electronic properties through the number of pyrene groups (4, n = 1; 6, n = 2). The prepared Py-BiV2+ showed strong light absorption, while retaining good redox features and chromic response features that were inherent to viologens. 4 exhibited accelerated photoinduced electron transfer in the presence of the electron donor (pyrene) and the generated 4' (radical cation) showed higher stability. Accordingly, Py-BiV2+ directly served as photosensitizers for the first time in the visible-light-induced C(sp3)–P and C(sp2)–P bonds formation. As expected, these novel viologen derivatives exhibited good catalytic performance and good substrate expansibility under ambient conditions.
Developing an efficient Zn-based catalyst modified with Trifluoromethanesulfonic acid (TfOH) ligand is extremely desirable for the acetylene hydration reaction. In this paper, with the use of a simple impregnation method, a series of Zn-TfOH/AC catalysts were synthesized, and the Zn-1.5TfOH/AC catalyst demonstrated the optimal catalytic performance with 96% acetylene conversion in the hydration of acetylene. The X-ray absorption fine structure (XAFS) spectra of the fresh Zn-1.5TfOH/AC catalysts demonstrated the establishment of the Zn-O4 coordination structure. According to the characterization results, TfOH ligands effectively inhibited carbon accumulation and Zinc loss, improved acidic sites and the dispersion of active metal, and produced more catalytic active site. Furthermore, the hydration reaction mechanism of Zn-TfOH/AC catalyst with Zn(OTf)2, TfO-ZnCl, and TfO-ZnOH complex configurations was explored by the Density Functional Theory (DFT) method, which showed that the activation barrier increased sequentially TfO-ZnOH < Zn(OTf)2 < TfO-ZnCl. Importantly, the OH− in TfO-ZnOH is involved in the reaction and regenerated by the dissociation of H2O, which lowers the energy barrier. This will provide a reference to design more efficient nonmercury catalysts for acetylene hydration.
The Ni−Al bimetallic catalysis of intramolecular enantioselective and regioselective C−H cyclization of 4-oxoquinazolines with tethered alkenes has been successfully developed. Some new secondary phosphine oxides (SPOs) with large steric hindrance (SPO6-11) were designed and successfully synthesized from readily available chiral amines or amino acids. The developed chiral SPOs as ligands or preligands demonstrate much higher efficiency in the asymmetric catalytic reactions than the reported traditional ones. A new class of chiral tricyclic pyrroloquinazolinones were obtained in up to 95% yield and 99% ee.
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