Latest ArticlesPoint mutations can be used as biomarkers to perform diagnosis for diseases. In this study, a nanorobot for low-abundance point mutation enrichment was constructed using DNA origami. The novel design achieved limits of detection of 0.1% and 1% for synthesized DNA samples and clinical gene samples, respectively. Resettability was a key property of this method, which also involved a simpler process, lower cost and shorter detection duration than traditional enrichment methods. This novel DNA nanorobot may enable the detection of tumor markers, potentially facilitating early cancer diagnosis.
A novel method for metal-free C-H borylation of 2-(N-methylanilino)-5-fluoropyridines and 2-benzyl-5-fluoropyridines has been reported. The 5-fluoropyridine directed borylation reaction exhibited high efficiency and site exclusivity. The useful protocol could be executed on a gram-scale easily and the borylated products showed good derivatization applications. Moreover, the practicality of the strategy was expanded by the fact that the directing group could be removed in an acceptable yield.
The construction of all-carbon molecule frameworks remains challenging. Herein, we report a facile and efficient one-pot synthesis of a novel all-carbon stair containing dimerized pentalene core using inexpensive cyclopropyl alkyne catalyzed by in situ generated Cu(I) from the comproportionation reaction of Cu(II) salt and Cu powder under mild reaction conditions. The reaction proceeds via sequential acetylenic coupling, followed by cyclization and [2 + 2] cycloaddition to directly produce pentalene dimer, which is difficult to access by other established methods. Different mechanistic paths were studied for the pentalene formation using density functional theory, suggesting that the reaction also proceeds through acetylenic coupling followed by cyclization and [2 + 2] cycloaddition. Based on the activation energy barriers, Path 1 has the rate-determining step of 38.63 kcal/mol, which is the most thermodynamically preferred one among the four paths.
N6-methyldeoxyadenosine (6mdA) modification is considered as a new epigenetic mark that may play important roles in various biological processes. However, it remains unclear about the effect of 6mdA on DNA replication in human cells. Herein, we combined next-generation sequencing with shuttle vector technology to explore how 6mdA affects the efficiency and accuracy of DNA replication in human cells. Our results showed that 6mdA neither blocked DNA replication nor induced mutations in human cells. Moreover, we found that the depletion of translesion synthesis DNA polymerase (Pol) κ, Pol η, Pol ι or Pol ζ did not significantly change the biological consequences of 6mdA during replication in human cells. The negligible impact of 6mdA on DNA replication is consistent with its potential role in epigenetic gene expression.
Although peroxidase-like nanozymes have made great progress in bioanalysis, few current nanozyme-based biosensors are constructed for discriminating isomers of organic compounds. Herein, fluorescent metal-organic framework (MOF)-based nanozyme is utilized for phenylenediamine isomers discrimination and detection. NH2-MIL-101(Fe), as a member of Fe-based MOFs, functions as not only fluorescent indicator but also peroxidase mimics. In the presence of H2O2, NH2-MIL-101(Fe) can catalyze the oxidation of o-phenylenediamine (OPD) and p-phenylenediamine (PPD) into their corresponding oxidation products (OPDox and PPDox), which in turn quench its intrinsic fluorescence at 445 nm via inner filter effect (IFE). Differently, a new fluorescence peak at 574 nm is observed for OPDox. Thus, a ratiometric fluorescence method for the detection of OPD can be designed with the fluorescence intensity ratio F574/F445 as readout. This proposed strategy displays excellent discrimination ability for three phenylenediamines and may open new applications of MOFs in environmental science.
Due to the involvement of four-electron transfer process at photoanode, water oxidation is the rate-limiting step in water splitting reaction. To settle this dilemma, ZnCo2O4 nanoparticles are combined with BiVO4 to form a p-n ZnCo2O4/BiVO4 heterojunction photoanode, which is proved by an input voltage−output current test. The built-in electric field formed within the heterojunction structure promotes the effective separation of electrons and holes. ZnCo2O4 is also an effective water oxidation cocatalyst, since it could cause the holes entering the electrode/electrolyte interface rapidly for the subsequent water oxidation reaction. The photocurrent density of ZnCo2O4/BiVO4 composite photoanode reaches 3.0 mA/cm2 at 1.23 V vs. RHE in 0.5 mol/L sodium sulfate under AM 1.5G simulated sunlight, about 2.1 times greater than that of BiVO4 (1.4 mA/cm2). These results suggest the potential of ZnCo2O4 nanoparticles for improving photoelectrochemical water splitting anode materials.
Supported NiCu bimetallic catalysts have been produced in-situ on commercial Al2O3 by using layered double hydroxides as precursors. The resulting catalysts show a uniform Ni and Cu distribution, thus providing good activity and selectivity in the reforming reaction of n-heptane. The catalytic performance has been found to depend on the Cu/Ni ratio, revealing the synergic catalysis between homogeneously dispersed Ni and Cu sites. The good catalysis of NiCu bimetallic catalysts makes it possible to partly or even completely replace Pt with NiCu bimetallic catalysts.
Metal-organic frameworks (MOFs) as a type of crystalline heterogeneous catalysts have shown potential application in photocatalytic CO2 reduction. However, MOF catalysts with high efficiency and selectivity are still in pursuit. Herein, by a bimetallic strategy, the catalytic performance of a Co-MOF for photocatalytic CO2 reduction was enhanced. Specifically, the Co-MOF based on 4, 5-dicarboxylic acid (H3IDC) and 4, 4ʹ-bipydine (4, 4ʹ-bpy) can catalyze CO2 reduction to CO, with high efficiency but relatively low selectivity. After replacement of 2/3 Co(Ⅱ) with Ni(Ⅱ) within Co-MOF, the resulted isostructural Co1Ni2-MOF not only retains high efficiency for photocatalytic CO2 reduction, but also shows enhanced CO selectivity. The CO evolution rate reaches 1160 µmol g−1 h−1 and the CO selectivity reaches as high as 94.6%. The enhanced photocatalytic CO2 reduction performance is supported by theoretical calculation results. This case demonstrates that bimetallic strategy is an effective mean to optimize the catalytic performance of MOF catalysts for photochemical CO2 reduction.
A novel meroterpenoid, named meroterpenthiazole A (1), was isolated from the deep-sea-derived Penicillium allii-sativi. Its structure was established by extensive spectroscopic and computational methods. Meroterpenthiazole A bears a rare benzothiazole moiety in nature. Compound 1 significantly inhibited retinoid X receptor (RXR)-α transcriptional effect (KD = 12.3 µmol/L) through a novel binding mechanism.
Foodborne pathogenic bacteria have been considered as a major risk factor for food safety. It is of great significance to carry out in-field screening of pathogenic bacteria to prevent the outbreaks of foodborne diseases. In this study, a portable lab-on-a-disc platform with a microfluidic disc was developed for rapid and automatic detection of Salmonella typhimurium using a nickel nanowire (NiNW) net for effective separation of target bacteria, horseradish peroxidase nanoflowers (HRP NFs) for efficient amplification of biological signals, and a self-developed smartphone APP for accurate analysis of colorimetric images. First, the microfluidic disc was preloaded with reagents and samples and centrifuged to form one bacterial sample column, one immune NiNW column, one HRP NF column, two washing buffer columns and one tetramethylbenzidine (TMB) column, which were separated by air gaps. Then, a rotatable magnetic field was specifically developed to assemble the NiNWs into a net, which was automatically controlled by a stepped motor to successively pass through the sample column for specific capture of target bacteria, the HRP NF column for specific label of target bacteria, the washing columns for effective removal of sample background and non-specific binding NFs, and the TMB column for colorimetric determination of target bacteria. The color change of TMB from colorless to blue was finally analyzed using the smartphone APP to quantitatively determine the target bacteria. This lab-on-a-disc platform could detect Salmonella typhimurium from 5.6×101 CFU/20 μL to 5.6×105 CFU/20 μL in 1 h with a lower detection limit of 56 CFU/20 μL. The recovery of target bacteria in spiked chicken samples ranged from 97.5% to 101.8%. This portable platform integrating separation, labeling, washing, catalysis and detection onto a single disc is featured with automatic operation, fast reaction, and small size and has shown its potential for in-field detection of foodborne pathogens.
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