Latest ArticlesFour unprecedented sulfur-containing cytochalasans, thiocytochalasins A−D (1−4), were isolated from an endophytic fungus Phoma multirostrata XJ-2-1. Thiocytochalasins A (1) and B (2) feature a novel 5/6/14/5 tetracyclic scaffold, which are the first examples of cytochalasan containing a thiophene moiety. Thiocytochalasins C (3) and D (4) are epimeric cytochalasan homodimers formed via a thioether bridge. Their structures with absolute configurations were established by detailed analysis of the HRESIMS, NMR, and X-ray crystallography. The plausible biogenetic pathway of 1−4 was postulated. Compounds 3 and 4 exhibited significant cytotoxicity against CT26 cells with IC50 values of 0.85 and 0.76 µmol/L, respectively.
Inflammatory bowel disease (IBD) is a chronic and recurrent disease of the gastrointestinal tract, mainly including Crohn's disease (CD) and ulcerative colitis (UC). However, current approaches against IBD do not precisely deliver drugs to the inflammatory site, which leads to life-long medication and serious side effects that can adversely impact patients' adherence. It is necessary to construct optimal drug delivery systems (DDSs) that can target drugs to the region of inflammation, thereby improve therapeutic efficacy and reduce side effects. With the burgeoning development of nanotechnology-based nanomedicines (NMs) and prodrug strategy, remarkable progresses in the treatment of IBD have been made in recent years. Herein, the latest advances are outlined at the intersection of IBD treatment and nanotherapeutics as well as prodrug therapy. First, the pathophysiological microenvironment of inflammatory sites of IBD is introduced in order to rationally design potential NMs and prodrugs. Second, the necessity of NMs for the IBD therapy is elaborated, and the representative nanotherapeutics via passive targeted and active targeted NMs developed to treat the IBD are overviewed. Furthermore, the emerging prodrug-based therapeutics are summarized, including 5-aminosalicylic acid-, amino acid-, and carbohydrate-conjugated prodrugs. Finally, the design considerations and perspectives of these NMs and prodrugs-driven IBD therapeutics in the clinical translation are spotlighted.
Peroxide ligation of aqueous metal–oxo clusters provides rich speciation and structural diversity. Here, three novel transition-metal derivatives of polyoxometalate anions, [Ni2(H2O)10{P4Ta6(O2)6O24}]6– (1a), [Zn(H2O)4{P4Ta6(O2)6O24}]8– (2a) and [Cd(H2O)4{P4Ta6(O2)6O24}]8– (3a), have been successfully synthesized by adopting a one-pot reaction strategy. All of these hexatantalates are built from a new-type phosphorus-incorporated hexatantalates. We investigated the solution behaviors, and the peak assignments of the MS spectra indicated some degree of stability of them in water. Furthermore, the proton-conducting ability of compound 1a was also explored and it has shown well conductivity at high relative humidities, with conductivity achieved 1.22 × 103 S/cm (85 ℃, 90%RH).
Electrochemical nitrogen reduction reaction (NRR) has been considered as an appealing and sustainable method to produce ammonia from N2 under ambient conditions, attracting increasing interest. Limited by low solubility of N2 in water and high stability of NN triple bond, developing NRR electrocatalysts with both strong N2 adsorption/activation and high electrical conductivity remain challenging. Here, we demonstrate an efficient strategy to develop NRR electrocatalyst with synergistically enhanced N2 adsorption/activation and electrical conductivity by heteroatom doping. Combining computational and experimental study, the DFT-designed Ti-doped SnO2 exhibits significantly enhanced NRR performance with ammonia yield rate of 13.09 µg h−1 mg−1 at −0.2 V vs. RHE. Particularly, the Faradaic efficiency reaches up to 42.6%, outperforming most of Sn-based electrocatalysts. The fundamental mechanism for improving NRR performance of SnO2 by Ti doping is also revealed. Our work highlights a powerful strategy for developing high-activity electrocatalysts for NRR and beyond.
Semiconductor photocatalysis holds great promise for breaking the inert chemical bonds under mild condition; however, the photoexcitation-induced modulation mechanism has not been well understood at the atomic level. Herein, by performing the DFT+U calculations, we quantitatively compare H2 activation on rutile TiO2(110) under thermo- versus photo-catalytic condition. It is found that H2 dissociation prefers to occur via the heterolytic cleavage mode in thermocatalysis, but changes to the homolytic cleavage mode and gets evidently promoted in the presence of photoexcited hole (h+). The origin can be ascribed to the generation of highly oxidative lattice O-radical (Obr·-) with a localized unoccupied O-2p state. More importantly, we identify that this photo-induced promotion effect can be practicable to another kind of important chemical bond, i.e., C–H bond in light hydrocarbons including alkane, alkene and aromatics; an exception is the C(sp1)-H in alkyne (HC≡CH), which encounters inhibition effect from photoexcitation. By quantitative analysis, the origins behind these results are attributed to the interplay between two factors: C-H bond energy (Ebond) and the acidity. Owing to the relatively high Ebond and acidity, it favors the C(sp1)-H bond to proceed with the heterolytic cleavage mode in both thermo- and photo-catalysis, and the photoexcited Obr·- is adverse to receiving the transferred proton. By contrast, for the other hydrocarbons with moderate/low Ebond, the Obr·- would enable to change their activation mode to a more favored homolytic one and evidently decrease the C–H activation barrier. This work may provide a general picture for understanding the photocatalytic R–H (R = H, C) bond activation over the semiconductor catalyst.
Real-time exploring the cellular endocytic pathway of viral capsid proteins (VCPs) functionalized nanocargos at the single-particle level can provide deep insight into the kinetic information involved in virus infection. In this work, porcine circovirus type 2 (PCV2) VCPs with different functions are modified onto the surface of upconversion nanoparticles (VCPs-UCNPs) to investigate the cellular internalization process in real-time. Clathrin-mediated endocytosis is found to be the essential uptake mechanism for these VCPs-UCNPs. Besides, it is verified that P1-UCNPs (PCV2 VCPs with nuclear localization signal, namely P1) can be easily assembled close to the perinuclear area, which is different from that of P2-UCNPs (PCV2 VCPs without nuclear localization signal, namely P2). Interestingly, multistep entry processes are observed. Particularly, confined diffusion is observed during the transmembrane process. The intracellular transport of VCPs-UCNPs is dependent on microtubules toward the cell interior. During this process, P1-UCNPs display increased velocities with active transport, while diffusion much faster around the perinuclear area. But for P2-UCNPs, there are only two phases involved in their endocytosis process. This study presents distinct dynamic mechanisms for the nanocargos with different functions, which would make a useful contribution to the development of robust drug delivery systems.
Electrochemical reduction of CO2 to value-added chemicals holds promise for carbon utilization and renewable electricity storage. However, selective CO2 reduction to multi-carbon fuels remains a significant challenge. Here, we report that B/N-doped sp3/sp2 hybridized nanocarbon (BNHC), consisting of ultra-small nanoparticles with a sp3 carbon core covered by a sp2 carbon shell, is an efficient electrocatalyst for electrochemical reduction of CO2 to ethanol at relatively low overpotentials. CO2 reduction occurs with a Faradaic efficiency of 58.8%-69.1% for ethanol and acetate production at -0.5 ~ -0.6 V (vs. RHE), among which 51.6%-56.0% is for ethanol. The high selectivity for ethanol is due to the integrated effect of sp3/sp2 carbon and B/N doping. Both sp3 carbon and B/N doping contribute to enhanced ethanol production with sp2 carbon reducing the overpotential for CO2 reduction to ethanol.
Ground-level ozone is one of the primary pollutants detrimental to human health and ecosystems. Catalytic ozone decomposition still suffers from low efficiency and unsatisfactory stability. In this work, we report a manganese-based layered double hydroxide catalyst (Co3Mn-LDH), which exhibited a superior ozone decomposition performance with the efficiency of 100% and stability over 7 h under a GHSV of 2,000,000 mL g-1h-1 and relative humidity of 15%. Even when the relative humidity increased to 50%, the ozone decomposition also reached 86%, which significantly exceeds as-synthesized MnO2 and commercial MnO2 in performance. The catalytic mechanism was studied by H2-TPR, FT-IR and XPS. The excellent performance of Co3Mn-LDH can be attributed to its abundant surface hydroxyl groups that ensured the preferentially surface enrichment of ozone, as well as the cyclic dynamic replenishment of electrons between multivalent Co2+/Co3+, Mn2+/Mn3+/Mn4+ and oxygen species that endowed the stable ozone decomposition. This work offers new insights into the design of efficient catalysts for ozone pollution control.
Solid-state batteries with high energy density and safety are promising next-generation battery systems. However, lithium oxide and lithium sulfide electrolytes suffer low ionic conductivity and poor electrochemical stability, respectively. Lithium halide solid electrolyte shows high conductivity and good compatibility with the pristine high-voltage cathode but limited applications due to the high price of rare metal. Zr-based lithium halides with low cost and high stability possess great potential. Herein, a small amount of In3+ is introduced in Li2ZrCl6 to synthesize Li2.25Zr0.75In0.25Cl6 electrolytes with a high room temperature Li-ion conductivity of 1.08 mS/cm. Solid-state batteries using Li2.25Zr0.75In0.25Cl6/Li5.5PS4.5Cl1.5 bilayer solid electrolytes combined with Li-In anode and pristine LiNi0.7Mn0.2Co0.1O2 cathode deliver high initial discharge capacities under different cut-off voltages. This work provides an effective strategy for enhancing the conductivity of Li2ZrCl6 electrolytes, promoting their applications in solid-state batteries.
The applications of fluorescence resonance energy transfer (FRET) are coming to be one of the simplest and most accessible strategy with super-resolved optical measurements. Meanwhile, nanomaterials have become ideal for constructing FRET-based system, due to their unique advantages of tunable emission, broad absorption, and long fluorescence (FL) lifetime. The limitations of traditional FRET-based detections, such as the intrinsic FL, auto-FL, as well as the short FL lifetime, could be overcome with nanomaterials. Consequently, numbers of FRET-based nanomaterials have been constructed for precise, sensitive and selective detections in biological systems. They could act as both energy donors and/or acceptors in the optical energy transfer process for biological detections. Some other nanomaterials would not participate in the energy transfer process, but act as the excellent matrix for modifications. The review will be roughly classified into nanomaterial-involved and uninvolved ones. Different detection targets, such as nucleic acids, pathogenic microorganisms, proteins, heavy metal ions, and other applications will be reviewed. Finally, the other biological applications, including environmental evaluation and mechanism studies would also be summarized.
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