Latest ArticlesExtracellular vesicles (EVs) are membrane vesicles secreted by cells, playing critical roles in mediating intercellular communications for various physiological and pathological processes. Most of the EV analysis is currently performed at the bulk level, obscuring the origin of the EVs and diverse characteristics of the individual extracellular vesicle. Technologies to analyze the extracellular vesicles at the single-cell and single-vesicle levels are needed to evaluate EV comprehensively and decode the heterogeneity underlying EV secretion. Microfluidic platforms that could control and manipulate fluids at the microscale provide an efficient way to achieve the aims. Various microfluidics-based technologies are emerging to realize single-cell EV secretion analysis and single EV analysis, which would be summarized in this mini-review.
As human stem cells with the special pluripotency play important roles in the innovative drug discovery and regenerative medicine, development of extracellular matrix (ECM) mimetics or functional materials that can support stem cell growth and propagation is of high significance. Despite numerous efforts spent, one major limitation restricting the wide applications of stem cells to the clinical translation is the lack of efficient strategies for low cost and large-scale stem cell production under xeno-free culture conditions. Herein, we reported a new strategy with peptides-modified polystyrene-based polymers coated onto the surface of coverslips for the growth and reproduction of human embryonic stem cells (hESCs). The modified peptides are the active parts of proteins which has been shown to contribute to the pluripotent stem cell attachment or proliferation. The peptides were linked to the glass coverslips coated by the polymer materials via chemical crosslinking, and the composite substrates successfully maintain the long-term growth of HUES-7, H7 and DF699. Our study shows that the coating of polystyrene-derived polymer modified by our developed peptides is a good matrix for long-term growth and reproduction of stem cells. This polystyrene-derived polymer substrate can be produced in large scale and stored for a long time. The most important thing is that it can support the growth of undifferentiated human pluripotent stem cells (hPSCs) for more than ten passages, which could provide a new and relatively easy way to amplify hESCs in vitro.
Dimethyl ether (DME), as a promising alternative to diesel fuel and liquefied petroleum gas, has attracted considerable attention in catalysis domain. The catalytic direct synthesis of DME from syngas is an up-and-coming route but remains a challenge. In this work, we firstly prepared a Cu-embedded porous Al2O3 bifunctional catalyst (Cu@Al2O3-dp) by filling Cu-1, 3, 5-benzenetricarboxylate metal-organic framework (Cu-BTC MOF) with Al(OH)3 followed by a two-step calcination process (400 ℃ for 4 h and 600 ℃ for 1 h), exhibiting excellent catalytic performance for direct synthesis of DME from syngas. Cu@Al2O3-dp catalyst demonstrates much higher CO conversion (25.7% vs. 15.4%) and extremely higher DME selectivity (90.4% vs. 63.9%) with the increased catalytic stability compared to the supported Cu catalyst on MOF-derived porous Al2O3 (Cu/Al2O3) prepared by incipient wetness impregnation method, ascribed to the unique embedding-type structure, promoted Cu dispersion and stronger metal-support interaction. This work not only provides an efficient syngas-to-DME catalyst, but also paves a new way for designing highly-efficient core-shell bifunctional catalysts for diverse consecutive reactions.
Selective hydrogenation of substituted nitroarenes is an important reaction to obtain amines. Supported metal catalysts are wildly used in this reaction because the surface structure of supports can tune the properties of the supported metal nanoparticles (NPs) and promote the selectivity to amines. Herein, Pt NPs were immobilized on FeOOH, Fe3O4 and α-Fe2O3 nanorods to synthesize a series of iron compounds supported Pt catalysts by liquid phase reduction method. Chemoselective hydrogenation of 3-nitrostyrene to 3-aminostyrene was used as probe reaction to evaluate the performance of the catalysts. The results show that Pt/FeOOH exhibits the highest selectivity and activity. FeOOH support with pores and -OH groups can tune the electronic structure of Pt NPs. The positive charge of Pt NPs supported on FeOOH is key factor for improving the catalytic performance.
The photocatalytic reduction of CO2 to energy-rich chemicals is highly appealing for alleviation of energy crisis and environment pollution. The introduction of different active sites is a key factor to determine the reaction activity and selectivity. Here, we demonstrate the metal ion-dependent performance for photocatalytic CO2 reduction by anchoring transition metal ions (Co2+ and Ni2+) in an amine-functionalized boron imidazolate framework (BIF-43). As a result, Ni@BIF-43 realized a high selectivity of 90.2% for the CO2-to-CO, while Co@BIF-43 achieved more efficient conversion with a high CO production rate of 2036.0 µmol g−1 h−1. Significantly, precise control of isolated metal site on a well-defined structure through coordination-assisted strategies enables us to better understand the specific effects of different metal-ion species on photoreduction of CO2 as well as the catalytic mechanism.
Valeriaquinone A (1), an unprecedented anthraquinone-coumarin hybrid, was isolated from the roots of Knoxia valerianoides. Its structure was determined by extensive spectroscopic analyses and X-ray diffraction. The plausible biosynthetic pathways for 1 were proposed. Compound 1 exhibited strong protein tyrosine phosphatase 1B (PTP1B) inhibition with high selectivity (> 30 fold) over homologous T cell protein tyrosine phosphatase (TCPTP) potentially by binding to an allosteric site predicted by kinetic analysis and molecular docking. Moreover, compound 1 showed significant cytotoxic activities against three human hepatoma cell lines (HepG2, QGY-7703, and SMMC-7721) with half maximal inhibitory concentration (IC50) values of 1.39 ± 0.2, 10.34 ± 2.09, and 5.56 ± 0.47 µmol/L, respectively.
Sophoralines A-C, three novel [2 + 2] cycloaddition dimers of matrine-based alkaloids with an unprecedented 6/6/6/6/4/6/6/6/6 nonacyclic skeleton containing 11 stereogenic centers, were isolated from Sophora alopecuroides. Their structures were determined by spectroscopic methods, and the absolute configurations were further determined by single-crystal X-ray diffraction analysis for 1 and quantum chemical calculations of electronic circular dichroism (ECD) spectra for 2 and 3. Moreover, 1 exhibited excellent hepatoprotective activities in acetaminophen-induced liver injury in vitro and in vivo.
Coordination polymers (CPs) have great potential to be used in electrocatalysis owing to their designable compositions and structures. It is highly challenging to apply CPs as electrocatalysts for oxygen evolution reaction (OER) on account of insufficient catalytic efficiency and relatively poor stability of current electrocatalysts. Herein, through a mixed-metal strategy, one-dimensional CoNi1--HIPA with dual active sites was synthesized and studied for OER electrocatalysts. By changing the metal ratio of CoNi1--HIPA, the OER performance was well regulated. The optimized Co1/2Ni1/2-HIPA exhibited minimum reaction activation energy, and represented an overpotential of 367 mV to reach 10 mA/cm2 at 25 ℃. Moreover, an overpotential of 314 mV at 10 mA/cm2 was obtained from Co1/2Ni1/2-HIPA at 55 ℃. This mixed-metal strategy provides a feasible way for adjusting the electronic states of the electrocatalysts to improve the electrocatalytic OER performance.
Aprotic Li-CO2 batteries have attracted growing interest due to their high theoretical energy density and its ability to use green house gas CO2 for energy storage. However, the poor ability of activating CO2 in organic electrolyte often leads to the premature termination of CO2 reduction reaction (CO2RR) directly. Here in this work, cetyl trimethyl ammonium bromide (CTAB) was introduced into a dimethyl sulfoxide (DMSO) based Li-CO2 battery for the first time to enhance the CO2RR. Significantly improved electrochemical performances, including reduced discharge over-potential and increased discharge capacity, can be achieved with the addition of CTAB. Ab initio molecular dynamics (AIMD) simulations show that quaternary ammonium group CTA+ can accelerate CO2 reduction process by forming more stable contact ion pair (CIP) with CO2-, reducing the energy barrier for CO2RR, thus improving the CO2 reduction process. In addition, adding CTA+ is also favorable for the solution-phase growth of discharge products because of the improved migration ability of stable CTA+-CO2- CIP in the electrolyte, which is beneficial for improving the utilization ratio of cathode. This work could facilitate the development of CO2RR by providing a novel understanding of CO2RR mechanism in organic system.
Uncontrollable hemorrhage remains staple trouble in surgical procedures and a leading cause after major trauma. The bleeding issue may trigger various pathologic scenarios that can lead to tissue morbidities and mortalities, and currently available on-site hemostatic agents are confined to a narrow therapeutic index and may carry the risk of immunogenicity. Inspired by the crucial role of platelets in the process of thrombus, a platelet-mimetic plateletsome with wound targeting and blood coagulation properties is developed for hemorrhage control. Plateletsome is formulated by integrating platelet membranes with functionalized synthetic liposomes and exhibits superior wound targeting and effective hemostasis properties. It presents less blood loss and shorter hemostasis time than the platelet membrane vehicles or the conventional liposomes in the mouse tail transection model. The strong homing of the biomimetic plateletsome to the thrombus was also confirmed, demonstrating the potential of this engineered cell membrane vesicle as a biomimetic hemostat for bleeding treatment.
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