Latest ArticlesConsidering that hydrogen peroxide (H2O2) plays significant roles in oxidative stress, the cellular signal transduction and essential biological process regulation, the detection and imaging of H2O2 in living systems undertakes critical responsibility. Herein, we have developed a novel two-photon fluorescence turn on probe, named as Pyp-B for mitochondria H2O2 detection in living systems. Selectivity studies show that probe Pyp-B exhibit highly sensitive response toward H2O2 than other reactive oxygen species (ROS) and reactive nitrogen species (RNS) as well as biologically relevant species. The fluorescence colocalization studies demonstrate that the probe can localize in the mitochondria solely. Furthermore, as a bio-compatibility molecule, the highly selective and sensitive of fluorescence probe Pyp-B have been confirmed by its cell imaging application of H2O2 in living A549 cells and zebrafishes under the physiological conditions.
For drop-on-demand (DOD) inkjet printing, stable and single ink droplet formation without satellite dots is the key to improve the print quality. The formation of stable and single droplet is influenced by filament break up and the polymer chain's coil-stretch transition behavior. In this paper, the droplet formation behaviors of polyfluorene (PFO) ink at various driving voltages (V), polymer chain's coil-stretch transition mechanism and its effects on single ink droplet formation are investigated. It indicates that when 58 < V ≤ 63 V, a single and stable droplet is formed with a pulse time of 38.5 μs. At this stage, the Weissenberg number (Wi) < 0.5, the PFO molecular chain is coiled to guarantee stable and single droplets. When V > 63 V, Wi > 0.5, the PFO molecular chain is stretched because of the high hydrodynamic forces, resulting unwanted satellite droplets. When 55 < V ≤ 58 V, the droplet shrinks into the nozzle, which indicates that the kinetic energy supplied by the deformation of the piezoelectric transducer isn't enough to force the droplet to be jetted from the nozzle.
An efficient method for the synthesis of functionalized chroman-4-ones induced by visible light via the radical cyclization reaction of sulfinic acids and o-(allyloxy)arylaldehydes at room temperature was described. The corresponding products were isolated with moderate to good yields. Radical mechanism was proposed for this transformation. Anti-microbial activity of some desired compounds were screened.
To explore the effects of microenvironmental adjustments on fluorescence, a pH-sensitive nano-composite system based on fluorescence resonance energy transfer (FRET) was constructed. The model system included a modified triblock copolymer (polyhistidine-b-polyethylene glycol-b-polycaprolactone) and gold nanoparticles. A near-infrared dye was used as the donor, and spectrally matched gold nanorods, attached after C-terminus modification with α-lipoic acid, were used as the receptor to realize control of the FRET effect over the fluorescence intensity for two polymer configurational changes (i.e., "folded" and "stretched" states) in response to pH. After synthesis and characterization, we investigated the self-assembly behavior of the system. Analysis by quartz crystal microbalance revealed the pH sensitivity of the polymer, which exhibited "folding" and "stretching" states with changes in pH, providing a structural basis for the FRET effect. Fluorescence spectrophotometry investigations also revealed the regulatory impact of the assembled system on fluorescence.
Cp*Co(Ⅲ)-catalyzed direct C-H amidation of azines has been developed. This conversion could proceed smoothly in the absence of external oxidants, acids or bases, with excellent regioselectivity and broad functional group tolerance. CO2 was released as the sole byproduct, thus providing an environmentally benign amidation process. The products obtained are important intermediates in organic synthesis.
Vascular endothelial growth factor (VEGF)-vascular endothelial growth factor receptor (VEGFR) pathways are essential in tumor angiogenesis, growth and metastasis. Studies on anti-angiogenic therapy have been mostly focused on the blockage of VEGF-VEGFR pathways. We report an extracellularly transformable peptide-based nanomaterial to develop artificial extracellular matrix (ECM)-like networks for high-efficient blockage of natural VEGF-VEGFR interactions. The transformable peptide-based nanomaterial transforms from nanoparticles into nanofibers upon binding to VEGFR in solution. In addition, the transformable peptide-based nanomaterial forms ECM-like fibrous networks on VEGFR overexpressed cells, inhibiting the VEGF-VEGFR interactions and the subsequent angiogenesis. The tube formation is reduced by nearly 85.1% after treatment. This strategy shows excellent potential for anti-angiogenesis, and inhibition of tumor invasion and metastasis.
As a highly strained small molecule, [1.1.1]propellane has been widely used in various synthetic transformations owing to the exceptional reactivity of the central bond between the two bridgehead carbons. Utilizing strain-release approaches, the rapid development of strategies for the construction of bicyclo[1.1.1]pentane (BCP) and cyclobutane derivatives using [1.1.1]propellane as the starting material has been witnessed in the past few years. In this review, we highlight the most recent advances in this field. Accordingly, the reactivity of [1.1.1]propellane can be divided into three pathways, including radical, anionic and transition metal-catalyzed pathways under appropriate conditions.
The deconstructive reorganization strategy for the synthesis of benzene-containing products from the kojic acid- and maltol-derived alkynes has been recently reported. In this strategy, kojic acid and maltol are analogous to the "Transformers", which can transform into benzofurans and benzaldehydes via annulation reactions. Under the synthetic standpoint, this deconstructive reorganization strategy features high atom economy, innate scalability and functional group tolerance. In the near future, we believe that this unique method will be widely investigated and other novel transformations of kojic acid and maltol will be discovered.
A visible-light induced metal-free approach was described for the hydroxyalkylation of 2H-benzothiazoles with alcohols by using selectfluor as the oxidant. A variety of 2H-benzothiazoles and alcohols could be tolerated, providing a mild and simple method for the synthesis of C2-hydroxyalkylated 2H-benzothiazoles in moderate to good yields. Besides, ethers were also compatible in this reaction, leading to corresponding C2 ether-substituted 2H-benzothiazoles with high regioselectivity.
Generation of 3-sulfonated 2H-pyrrol-2-ones through a three-component reaction of allenoic amides, sulfur dioxide, and aryldiazonium tetrafluoroborates under metal-free conditions is achieved. This transformation proceeds under mild conditions without the addition of catalysts or additives, giving rise to 3-sulfonated 2H-pyrrol-2-ones in moderate to good yields. Good functional group compatibility is observed. A plausible mechanism is proposed, which is initiated by aryl radicals formed in situ from aryldiazonium tetrafluoroborates and DABCO·(SO2)2. Additionally, excellent chemoselectivity and regioselectivity are presented in this transformation.
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