Latest ArticlesRegulation of cell fate requires the establishment and erasure of 5-methylcytosine (5mC) in genomic DNA. The formation of 5mC is achieved by DNA cytosine methyltransferases (DNMTs), whereas the removal of 5mC can be accomplished by various pathways. Aside from ten-eleven translocation (TET)-mediated oxidation of 5mC followed by thymine DNA glycosylase (TDG)-initiated base excision repair (BER), the direct deformylation of 5-formylcytosine (5fC) and decarboxylation of 5-carboxylcytosine (5caC) have also been discovered as the novel DNA demethylation pathways. Although these novel demethylation pathways have been identified in stem cells and somatic cells, their precise roles in regulating cell fate remain unclear. Here, we differentiate mouse embryonic stem cells (mESCs) into mouse embryoid bodies (mEBs), followed by further differentiation into mouse neural stem cells (mNSCs) and finally into mouse neurons (mNeurons). During this sequential differentiation process, we employ probe molecules, namely 2′-fluorinated 5-formylcytidine (F-5fC) and 2′-fluorinated 5-carboxyldeoxycytidine (F-5caC), for metabolic labeling. The results of mass spectrometry (MS) analysis demonstrate the deformylation and decarboxylation activities are progressively decreased and increased respectively during differentiation process, and this opposite demethylation tendency is not associated with DNMTs and TETs.
A novel amine-modified pillar[5]arene bonded porous silica adsorbent (DETA-P5S) was designed to be applied to dynamic CO2 adsorption and selective separation of CO2 over N2 and CH4 gases mixture. The results demonstrated that reasonable introduction of DETA into the BE-P5 bonded silica support has significantly increased the adsorption capacity of CO2. The DETA-P5S has the optimal adsorption capacity of 9.1 mmol/g with 5 vol% CO2 at 40 ℃. The main reason of this increased capacity could be attributed to the enhanced CO2 diffusion into porous adsorbent for its better dispersion in the pores of amine-pillar[5]arene cavity and active site of DETA. Furthermore, the dynamic saturation adsorption capacities of DETA-P5S were 7.11 (0.37) and 6.18 (0.44) mmol/g for CO2/N2 and CO2/CH4, respectively, both the gas mixtures showed high separation selectivity. Simultaneously, the DETA-P5S can maintain outstanding CO2 adsorption capacity after fifteen regeneration cycles. Consequently, the designed DETA-P5S could serve as a promising adsorbent for CO2 capture and storage.
Label-free immunoassay is confronted with a great challenge that its insufficient sensitivity for low concentration analytes, which can be assigned to the low catalytic efficiency of modified materials towards electroactive molecules. Herein, a universal MOF nanozyme-induced catalytic amplification strategy was proposed for constructing highly sensitive label-free electrochemical immunoassay. Specifically, the synthesized CuFe-MOF nanozyme with superior peroxidase (POD)-like activity, regarding as a MOF nanozyme model, can catalyze hydrogen peroxide to produce hydroxyl radicals (•OH), which can efficiently oxidize electroactive probe (such as 1,2-phenylenediamine (o-PD)) accompanying with intense electrochemical signals. Modification of MOF nanozyme on the electrode and capture of antibodies for binding target antigens hinder the catalytic process of MOF nanozyme toward o-PD, resulting in a gradual decrease in electrochemical signal with increasing target antigen concentration, enabling quantitative label-free immunoassay. Thus, a highly sensitive label-free immunosensor using MOF nanozyme-induced catalytic amplification achieved effective detection of Immunoglobulin G (IgG) with a wide linear range of 0.001–50 ng/mL and low detection limit of 0.45 pg/mL. This work proposes a promising nanozyme-induced catalytic amplification strategy for the development of label-free electrochemical immunoassay.
Nanographenes (NGs) with twisted backbones are emerging as new candidates for chiroptical materials. In this work, we describe a new strategy for synthesizing a [10]twistacene-embedded NG which exhibits a rare flag-hinge-like geometry. By neatly creating steric crowding on the [6]helicene breaches of the NG skeleton, the synthesis only provided homochiral isomers without generating the "meso‑" isomer. The formed NGs showed high luminescence with quantum yield up to 52%, and promising circularly polarized luminescence (CPL) performance with |glum| up to 5.0 × 10−3. Besides, these NGs also showed outstanding CPL brightness (BCPL) up to 305 L mol−1 cm−1 among chiral NGs.
Small peptides have attracted increasing attention for their unique features and diverse biological functions. Achieving rapid separation and accurate quantification, however, remains a challenge because of their low abundance and the co-existence of numerous structural isomers. In this study, we developed a novel approach using isotope chemical labeling for ultrasensitive determination of di/tripeptides in biological samples. We successfully synthesized a novel derivatization reagent, 4-(2-(ethoxymethylene)-3-oxobutanamido)-N,N,N-trimethylbenzenaminium iodide (EOTMBA) as well as its deuterium-labeled isotope reagent (d3-EOTMBA). A total of 97 small peptides, including 89 dipeptides and 8 tripeptides, could be completely derivatized in methanol within 1.5 h at 60 ℃. After EOTMBA labeling, analysis of these di/tripeptides were achieved within 22 min by LC-MS/MS analysis. The method demonstrated 86.3%–113% accuracy and the limit of quantification ranged from 0.25 fmol/L to 5 nmol/L. Using this method, we achieved ultrasensitive and accurate quantification of di/tripeptides in 147 plasma, 49 urine and 46 bile samples obtained from healthy individuals and patients with biliary tract diseases. The identified differential di/tripeptide biomarker panels showed promising diagnostic performance for patients with biliary tract cancer with area under the receiver operating curve values from 0.870 to 0.996. Furthermore, this method was successfully applied to quantify di/tripeptides in the extract of an animal-derived traditional Chinese medicine, Eupolyphaga sinensis Walker. These findings highlight the possible application of the analytical method in clinics and for the purposes of quality control of traditional Chinese medicines.
Efficient activation of molecular oxygen (O2) is considered a promising technique for the removal of antibiotics. However, how to effectively regulate electrons distribution to promote O2 activation remains a challenge at present. In this study, phosphorus and sodium co-doped carbon nitride (PNaCN) were designed to rearrange the electrons distribution to activate O2 for the degradation of tetracycline. The generation of •O2−was innovatively observed via in-situ O2 fitting Fourier transform infrared (FTIR) spectroscopy, demonstrating the outstanding O2 activation ability of PNa5. Density functional theory (DFT) further confirmed that the rational co-doping led to the rearrangement of local electrons, resulting in electron-rich Na sites and electron-deficient P sites. These sites exhibited greater susceptibility to O2 adsorption and charge transfer. Besides, the degradation rate of tetracycline was increased by 2.44 times using co-doped CN. This study provides a new inspiration for enhancing O2 activation by inducing electrons rearrangement.
The new reactions between o-hydroxyphenyl enaminones and Langlois reagent (CF3SO2Na) for the tunable synthesis of 3-(trifluoromethylthio) chromones and 3-trifluoromethylsulfinyl chromones are reported herein. Both type of reactions proceed under transition metal-free conditions. In addition, the conditions for the synthesis of 3-trifluoromethylsulfinyl chromones have also been found to be applicable for the synthesis of 3-alkyl/arylsulfinyl chromones.
A new 1,4-amidocyanation of 1,3-enynes with N-amidopyridin-1-ium salts and TMSCN using a copper and photoredox synergetic catalysis for producing α-amido allenyl nitriles is developed. Employing N-amidopyridin-1-ium salts as the amidyl radical precursors, the reaction enables the formation of two new bonds, one C(sp3)-N bond and one C(sp2)-C(sp) bond, in a single reaction step. This reaction represents a mild, general route to the construction of the α-amido allenyl nitrile architectures, which characterizes a broad scope, a good functional group compatibility and an excellent selectivity.
Gas adsorption remains an attractive area of research. The hierarchical structure can reduce diffusion limitations and facilitate molecular transport, while acid sites can be used as adsorption sites. These make zeolites widely used in the field of gas adsorption. How to obtain zeolite adsorbents with better adsorption properties by modulating the hierarchical structure and acid sites is a pressing issue nowadays. This review highlights the strategies to modulate the hierarchical structure as well as the acid sites; and then explains how these strategies are achieved. The mechanism of zeolite adsorption on gases is then described in terms of these two properties. Lastly, the adsorption properties of zeolites for certain gases under specific conditions are summarised. An outlook of zeolite hierarchical structures and acid site modulation strategies is given.
Heterojunction engineering is recognized as a promising strategy to modulate the photocatalytic properties of semiconductors. Herein, lead-free Cs2CuBr4 perovskite quantum dots (PQDs) were confined in a mesoporous CuO framework and a p-n type S-scheme heterojunction of Cs2CuBr4/CuO (CCB/CuO) photocatalyst was fabricated. Experimental characterizations confirmed the effective confinement of the Cs2CuBr4 PQDs in the mesoporous CuO framework, which enabled intimate contact in the interface of CCB/CuO heterojunction, thus facilitating the interfacial charge migration and separation between p-type CuO and n-type Cs2CuBr4. Owing to the outstanding charge transport property and CO2 adsorption capacity, the developed CCB/CuO heterojunction exhibited remarkably enhanced photocatalytic CO2 conversion efficiency with an electron consumption rate (Relectron) of 281.1 µmol g−1 h−1, which was approximately 2.8 times higher than that of pristine Cs2CuBr4. These findings provide some insights into the rational engineering design of lead-free perovskite-based heterostructures for efficient photocatalytic CO2 conversion.
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