Latest ArticlesHerein, we developed a fractionation-free negative enriching method incorporating methylamidation, site-selective dimethylation and aldehyde resin coupling (MADMAR) for in-depth C-terminome analysis. The methylamidation blocked the free carboxyl group on proteins first, followed by LysC digestion of methylamidated proteins. Then, the site-selective dimethylation blocked the N-terminal amino group of the digested peptides without affecting the amino groups of lysine. Finally, the aldehyde resin was used to capture non-C-terminal peptides containing amino groups from lysine, while leaving the C-terminal peptides without free amino group in the supernatant for its analysis. We identified 1359 database-annotated protein C-termini from 50 µg HeLa proteins, which was 74% more than our previous method based on aldehyde resin. Moreover, 279 protein neo-C-termini were identified.
An inexpensive Fe doped aluminoborate consisted of 18% Fe in PKU-1 material that exhibits high selectivity of 4-hydroxymethy-2,2-dimethyl-1,3-dioxolane (Solketal, 98.3%), considerable activity (TOF 51.7 h-1), and recyclable ability in the ketalization of glycerol to Solketal with acetone at 318 K has been developed. Our study demonstrated that the structure of Fe (less agglomerated iron species vs. FeOx clusters) can be tuned by changing Fe loading in the PKU-1 material, which correlated well with experimental observations. Furthermore, the surface boron sites were promoted by iron loading and behaved as Lewis-acid sites to facilitate the reaction process of glycerol ketalization, while the Solketal selectivity was closely related with the structure of iron species in PKU-1, which was proved by kinetic studies, density function theory (DFT) calculations, and a series of spectroscopy studies. This investigation demonstrates that the surface B sites can play important roles in the reaction instead of being spectators.
Development of new self-calibrating fluorescent sensing methods has been a popular research field with the aim of protecting the human health and environment sustainability. In this work, a novel Eu-based metal organic framework (MOF) Eu(2,6-NDC)(COO) (BUC-88) was developed by employing 2,6-NDC (2,6-naphthalenedicarboxylic acid) as bridging ligands. BUC-88 performed different sensing process toward quinolone antibiotics and tetracyclines antibiotics in terms of fluorescence intensity and color. BUC-88 exhibited excellent selectivity and sensitivity detection property toward enrofloxacin (ENR), norfloxacin (NOR) and ciprofloxacin (CIP) over other Pharmaceutical and Personal Care Products (PPCPs), accomplishing the detection limit of 0.12 μmol/L, 0.52 μmol/L, 0.75 μmol/L, respectively. Notably, BUC-88 acted as an excellent fluorescence sensor for tetracyclines antibiotics with fast response time (less than 1 s), high selectivity and sensitivity (LODs = 0.08 μmol/L). The fluorescent detection method was successfully used for visual and ultrasensitive detection of ENR, NOR, CIP and tetracycline hydrochloride (TC) in lake water with satisfied recovery from 99.75% to 102.30%. Finally, the photoinduced electron transfer and the competitive absorption of ultraviolet light are the main mechanisms for sensitive detection toward quinolone antibiotics and tetracyclines antibiotics.
Skeletonema costatum is a diatom widely distributed in red tide microalgae blooms and as one of the main algae causing harmful algal blooms, because of their rapid reproduction and production of toxic and harmful substances, often play a negative role in aquatic ecosystems, and human health and wellbeing. Bacillomycin D is a nonribosomal cyclic antifungal lipopeptide in the iturins family. In this study, Bacillomycin D was tested for its ability to inhibit the growth of S. costatum. The EC50 24h of Bacillomycin D on S. costatum was 24.70 μg/mL. The chlorophyll fluorescence parameters Fv/Fm, Fv/Fo, and yield of the diatoms decreased significantly with increasing concentrations of Bacillomycin D. Study of the mechanism showed that Bacillomycin D induced cell death by changing cell membrane permeability, promoting the release of cellular contents. In this study, transcriptomic analysis showed Bacillomycin D significantly inhibited the photosynthesis and metabolism of S. costatum. These findings investigated the inhibitory effect of Bacillomycin D on the growth of S. costatum and provided a theoretical foundation for the development of new environmentally friendly biological algicide.
In recent years, MoS2 catalyzed/cocatalyzed Fenton/Fenton-like systems have attracted wide attention in the field of pollution control, but there are few studies on the effect of H2O2 feeding way on the whole Fenton process. Here, we report a new type of composite catalyst (MoS2-Fex) prepared in a simple way with highly dispersed iron to provide more active sites. MoS2-Fex was proved to possess selectivity for singlet oxygen (1O2) in effectively degrading sulfadiazine with a wide pH adaptability (4.0~10.0). Importantly, the mechanism of the interaction between H2O2 and MoS2 on the Fenton reaction activity was revealed through the combination of experiment and density functional theory (DFT) calculations. Compared to the traditional "a large amount for one time" feeding way of H2O2, the "small amount for multiple times" of H2O2 feeding way can increase the degradation rate of sulfadiazine from 36.9% to 91.1% in the MoS2-Fex heterogeneous Fenton system. It is demonstrated that the "small amount for multiple times" of H2O2 feeding way can reduce the side reaction of decomposition of H2O2 by MoS2 and effectively improve the utilization rate of H2O2 and the stability of MoS2-Fex. Compared with Fe2O3-based Fenton system, MoS2-Fex can significantly save the amount of H2O2. Compared with nano-iron powder, the formation of iron sludge in MoS2-Fex system was significantly reduced. Furthermore, long-term degradation test showed that the MoS2-Fe75/H2O2 system could maintain the effectiveness of degrading organic pollutants for 10 days (or even longer). This study has a guiding significance for the large-scale treatment of industrial wastewater by improved Fenton technology in the future.
Accurate single-cell capture is a crucial step for single cell biological and chemical analysis. Conventional single-cell capturing often confront operational complexity, limited efficiency, cell damage, large scale but low accuracy, incompetence in the acquirement of nano-upgraded single-cell liquid. Flow cytometry has been widely used in large-scale single-cell detection, while precise single-cell isolation relies on both a precision operating platform and a microscope, which is not only extremely inefficient, but also not conducive to couple with modern analytical instruments. Herein, we develop a modular single-cell pipette (mSCP) microfluidic chip with high efficiency and strong applicability for accurate direct capture of single viable cell from cell suspensions into nanoliter droplets (30-1000 nL). The mSCP is used as a sampling platform for the detection of CdTe quantum dots in single cells with electrothermal atomic absorption spectrometry (ETAAS) for the first time. It also ensures precise single-cell sampling and detection by inductively coupled plasma mass spectrometry (ICP-MS).
Membrane tension plays a significant role in many cellular processes including cell adhesion, migration and spreading. Despite the importance of membrane tension, it remains difficult to measure in vivo. Recently, the development of non-invasive fluorescent probes have made great progress, especially excited-state deplanarization in molecular rotors has been applied to image membrane tension in living cells. Nevertheless, an intrinsic limitation of such kind of probe is that they depend on the lipid packing, and how the lipid packing responds to the membrane tension change remains unclear. Therefore, in this work, we used a polarity-sensitive membrane probe to investigate the possible response mechanism of lipid packing to the change of membrane tension that was regulated by osmotic shocks. The results showed that an increase in membrane tension could stretch the lipids apart with large displacements, and this change was not homogeneous on the whole membrane, instead, increase of membrane tension induced phase separation.
Spin-crossover (SCO) complexes with multiple spin states are promising candidates for high-order magnetic storage and multiple switches. Here, by employing the N, Nʹ-4-dipyridyloxalamide (dpo) ligand, we synthesize two Hofmann-type metal-organic frameworks (MOFs) [Fe(dpo){Ag(CN)2}2]·3DMF (1) and [Fe(dpo){Ag(CN)2}2]·0.5MeCN·2DEF (2), which exhibit guest dependent four-step SCO behaviors with the sequences of LS → ~LS2/3HS1/3 → LS1/2HS1/2 → ~LS3/10HS7/10 → HS and LS → ~LS2/3HS1/3 → LS1/2HS1/2 → ~LS1/4HS3/4 → HS, respectively. Therefore, the incorporation of hydrogen-donating/hydrogen-accepting groups into the Hofmann-type MOFs may effectively explore the multi-step SCO materials by tuning hydrogen-bonding interactions.
Numerous approaches have been used to modify graphitic carbon nitride (g-C3N4) for improving its photocatalytic activity. In this study, we demonstrated a facial post-calcination method for modified graphitic carbon nitride (g-C3N4-Ar/Air) to direct tuning band structure, i.e., bandgap and positions of conduction band (CB)/valence band (VB), through the control of atmospheric condition without involving any additional elements or metals or semiconductors. The synthesized g-C3N4-Ar/Air could efficiently degrade sulfamethazine (SMT) under simulated solar light, i.e., 99.0% removal of SMT with rate constant k1 = 2.696 h−1 within 1.5 h (4.9 times than pristine g-C3N4). Material characterizations indicated that the damaged/partial-collapsed structure and decreased nanosheet-interlayer distance for g-C3N4-Ar/Air resulted in the shift of band structure due to the denser stacking of pristine g-C3N4 through oxidative exfoliation and planarization by air calcination. In addition, the bandgap of g-C3N4-Ar/Air was slightly shrunk from 2.82 eV (pristine g-C3N4) to 2.79 eV, and the CB was significantly upshifted from −0.44 eV (pristine g-C3N4) to −0.81 eV, suggesting the powerful ability for donating the electrons for O2 to form •O2−. Fukui index (f –) based on theoretical calculation indicated that the sites of SMT molecule with high values, i.e., N9, C4 and C6, preferred to be attacked by •O2− and •OH, which is confirmed by the intermediates' analysis. The tuning method for graphitic carbon nitride provides a simple approach to regulate the charge carrier lifetime then facilitate the utilization efficiency of solar light, which exhibits great potential in efficient removal of emerging organic contaminants from wastewater.
2D transition metal dichalcogenides (TMDCs) have drawn an enormous amount of attention due to their fascinating properties and application potential in next-generation information process and storage. However, the lack of proper synthesis approach limits their application. Here, we report a controllable synthesis method to grow ultrathin MS2 (M = Ti, Nb, Zr) nanosheets with H2S-assisted chemical vapor deposition (CVD). We found that the presence of H2S plays an important role to control the morphology of nanosheets including the lateral size and the nucleation density. With the assistance of H2S, the growth of MS2 shows much thinner thickness with largely decreased nucleation density, beneficial for the device application, which can be attributed to the kinetics dominated growth. Our method hence opens a new avenue for the CVD growth of 2D TMDCs and the corresponding heterojunction, and paves the way for exploring their intriguing properties and applications.
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