Latest ArticlesEffective detection of cellular microenvironments and understanding of physiological activities in living cells remain a considerable challenge. In recent years, fluorescence (or Förster) resonance energy transfer (FRET) technology has emerged as a valuable method for real-time imaging of intracellular environment with high sensitivity, specificity and spatial resolution. Particularly, polymer-based imaging systems show enhanced stability, improved biodistribution, increased dye payloads, and amplified signal/noise ratio compared with small molecular sensors. This review summarizes the recent progress in FRET-based polymeric systems for probing the physiological environments in cells.
Primary alcohols are widely used in industry as solvents and precursors of detergents. The classic methods for hydration of terminal alkenes always produce the Markovnikov products. Herein, we reported a reliable approach to produce primary alcohols from terminal alkenes combining with biomass-derived allyl alcohol by tandem cross-metathesis/hydrogenation. A series of primary alcohol with different chain lengths was successfully produced in high yields (ca. 90%). Computational studies revealed that self-metathesis and hydrogenation of substrates are accessible but much slower than crossmetathesis. This new methodology represents a unique alternative to primary alcohols from terminal alkenes.
Due to the diversity and feasibility of structural modification for organic molecules, organic-based redox flow batteries (ORFBs) have been widely investigated, especially in aqueous solution under neutral circumstance. In this work, a symmetric aqueous redox flow battery (SARFB) was rationally designed by employing a bipolar redox active molecule (N, N'-dimethyl-4, 4-bipyridinium diiodide, MVI2) as both cathode and anode materials and combining with an anion exchange membrane. For one MVI2 flow battery, MV2+/MV·+ and I-/I3- serve as the redox couples of anode and cathode, respectively. The MVI2 battery with a working voltage of 1.02 V exhibited a high voltage efficiency of 90.30% and energy efficiency of 89.44% after 450 cycles, and crossover problem was prohibited. The comparable conductivity of MVI2 water solution enabled to construct a battery even without using supporting electrolyte. Besides, the bipolar character of MVI2 battery with/without supporting electrolyte was investigated in the voltage range between -1.2 V and 1.2 V, showing excellent stable cycling stability during the polarity-reversal test.
Recent studies have shown impressive transport behaviors of water and ions within lamellar MXene membranes, which endows great promise in developing advanced separation application based high performance MXene membranes. However, most of the researches focused on modification of MXene nanoflakes and optimizing interlayer distance, leaving the impact of membrane fabrication process marginal. In this work, we studied the water flux of membranes made by vacuum filtration using delaminated MXene nanoflakes as the building-blocks. Our results show that the water permeability is extremely sensitive to the process, especially at the drying process, loading and deposit rate of nanoflakes (the feeding concentration). We find that the voids from less ordered stack rather than in-plane defects and interlayer galleries contribute to the large water permeability. The voids can be effectively avoided via deposition of MXene nanoflakes at a slow rate. Manipulating the stack of MXene nanoflakes during vacuum filtration and drying are critical for development of MXene membranes with desired performance for water permeation.
The carbon quantum dots (CQDs) and their functionalized materials are promising in biomedical field because of their unique properties; meanwhile, a growing concern has been raised about the potential toxicity of these modified materials in biosystem. In this study, we synthesized original CQDs and two common functionalized CQDs including N-doped CQDs (NCQDs) and folic acid-modified CQDs (FA-CQDs), and compared the toxicity and biocompatibility with each other in vitro and in vivo. L929, C6 and normal cell MDCK were selected to detect the adverse reaction of these materials in vitro. No acute toxicity or obvious changes were noted from in vitro cytotoxicity studies with the dose of these CQD materials increasing to a high concentration at 1 mg/mL. Among these materials, the FA-CQDs show a much lower toxicity. Moreover, in vivo toxicity studies were performed on the nude mice for 15 days. The experimental animals in 10 or 15 mg/kg groups were similar with animals treated by phosphate buffer solution (PBS) after 15 days. The results of the multifarious biochemical parameters also suggest that the functionalized products of CQDs do not influence the biological indicators at feasible concentration. Our findings in vitro and in vivo through toxicity tests demonstrate that CQDs and their modified materials are safe for future biological applications.
With the emergence of multidrug-resistant tuberculosis and extensive drug-resistant tuberculosis strains, there is an urgent need to develop novel drugs for the treatment of tuberculosis. The respiratory chain is a promising target for the development of new antimycobacterial agents, and a growing number of compounds have been reported and some have entered clinical trials. In this review, we summarize the main features and the electron transfer process of the mycobacterial respiratory chain, and the recent progress in the search for new small molecule inhibitors targeting the three main potential targets in the respiratory chain of Mycrobacterium tuberculosis. Our emphasis is on the optimization strategy of QcrB inhibitors and the challenges of developing QcrB inhibitors as antituberculosis drugs due to the alternate bd-type oxidase oxidative compensation pathway are discussed.
Described here is the first example of Cu(0)-catalyzed intramolecular decarbonylative rearrangements of readily available N-aryl isatins assisted by solvent dimethyl sulfoxide (DMSO) under air atmosphere and additive-free conditions leading to various biologically important acridones in good to excellent yields. This novel transformation is proposed to go through a sequential DMSO-aided Cu insertion into the amide C—N bond, CO extrusion, Cu migration, reductive elimination and DMSO-aided proton migration processes, involving multiple types of bond cleavage and formation in a single chemical step.
A novel amphiphilic cationic block copolymer polylysine-b-polyphenylalanine (PLL-b-PPhe) was synthesized and self-assembled into micelles in aqueous solution, then shielded with poly(glutamic acid) (marked as PG/PLL-b-PPhe) to codeliver gene and drug for combination cancer therapy. Here, doxorubicin (DOX) was selected to be loaded into PLL-b-PPhe micelles and the drug loading efficiency was 8.0%. The drug release studies revealed that the PLL-b-PPhe micelles were pH sensitive and the released DOX could reach to 53.0%, 65.0%, 72.0% at pH 7.4, 6.8 and 5.0, respectively. In order to reduce positive charge and cytotoxicity of PLL-b-PPhe micelles, PG was used as shelding, simultaneously condensed with Bcl2 siRNA to form gene carrier system. Compared with PEI, PG/PLL-b-PPhe had excellent gene transfection efficiency, especially when the molar ratio of PLL to PPhe was 30:60 and the mixed mass ratio of PLL-b-PPhe to gene was 5:1. More importantly, DOX and Bcl2 siRNA gene codelivery system displayed remarkable cytotoxicity against B16F10 cells. Confocal laser scanning microscopy (CLSM) and flow cytometry were used to characterize endocytosis of the codelivery system, and confirmed that both DOX and Bcl2 siRNA had been endocytosed into B16F10 cells. The above results indicated that gene and drug codelivery was a promising strategy in future cancer therapy.
Graphene oxide (GO), an important chemical precursor of graphene, can stably disperse in aqueous surrounding and undergo aggregation as metal cations introduced. The usual instability of GO with ions is caused by the shielding effect of ions and crosslinking between GO and ions. However, the dynamic stability of GO under ions exchange still remains unclear. Here, we investigated the dynamic dispersion stability of GO with metal ions and observed a redispersion behavior in concentrated Fe3+ solution, other than permanent aggregation. The exchange with Fe3+ ions drives the reversion of zeta (ζ) potential and enables the redispersion to individual GO-Fe3+ complex sheets, following a dynamic electric double layer (EDL) mechanism. It is found that the specifically strong electrostatic shielding effect and coordination attraction between Fe3+ and functional oxygen groups allows the selective redispersion of GO in concentrated Fe3+ solution. The revealed dynamic dispersion stability complements our understanding on the dispersive stability of GO and can be utilized to fabricate graphene-metal hybrids for rich applications.
Sodium taurocholate cotransporting polypeptide (NTCP) is identified as the functional receptor for HBV entry, which is responsible for upregulated HBV transcription in the HBV life cycle. Besides, NTCP is also implicated in the progression of HBV-induced hepatocellular carcinoma (HCC). Thereby, NTCP-targeting entry inhibitors are proposed to suppress HBV infection and replication in HBV-induced hepatoma therapy. Herein, we integrated in silico screening and chemical synthesis to obtain a small-molecule NTCP inhibitor B7, which exhibited moderate anti-proliferative activities against HepG2 cells and anti-HBV activity in vitro. Additionally, CETSA assay, molecular docking, and MD simulation validated that B7 could bind to NTCP. Furthermore, western blot analysis demonstrated that B7 induced apoptosis with an increased expression of Bax and caspase 3 cleaving as well as a decreasing expression of Bcl-2 in HepG2 cells. Taken together, our study identified B7 as a novel NTCP inhibitor with anti-proliferation activities which might provide a new opportunity for HCC therapy.
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