Latest ArticlesApplication of matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI) to investigate the spatiotemporal alterations of lipids in biological tissues has brought many significant results. However, the presence of structural isomers varying in C=C double bond (DB) locations makes isomer-resolved MSI an urgent need. Herein, we introduce a new type of light-driven on-tissue [2 + 2] cycloaddition reaction coupled with MALDI-MS/MS imaging to identify lipid DB position isomers and their spatial signatures in biological tissues. 3-Benzoylpyridine was introduced as a novel derivatization reagent, and it exhibited great reactivity toward lipid C=C bond to form oxetanes under both ultraviolet light and visible light irradiation. With this approach, DB position isomers of lipids were imaged with highly differential levels in distinct regions of rat brain, providing an accurate and spatially resolved approach to study tissue lipidomics.
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.
Alcohol consumption is a critical risk factor contributing to a verity of human diseases. The incidence of alcohol use disorder increases across adolescence in recent years. Accumulating line of evidence suggests that alcohol-induced changes of DNA cytosine methylation (5-methyl-2'-deoxycytidine, 5mC) in genomes play an important role in the development of diseases. However, systemic investigation of the effects of adolescent alcohol exposure on DNA and RNA modifications is still lacked. Especially, there hasn't been any report to study the effects of alcohol exposure on RNA modifications. Similar to DNA modifications, RNA modifications recently have been identified to function as new regulators in modulating numbers of biological processes. In the current study, we systematically investigated the effects of alcohol exposure on both DNA and RNA modifications in peripheral blood of adolescent rats by liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS) analysis. The developed LC-ESI-MS/MS method enabled the sensitive and accurate determination of 2 DNA modifications and 12 RNA modifications. As for the alcohol exposure experiments, the adolescent rats were intraperitoneally injected with ethanol with an interval of one day for a total 14 days. The quantification results by LC-ESI-MS/MS analysis showed that adolescent alcohol exposure could alter both DNA and RNA modifications in peripheral blood. Specifically, we observed an overall decreased trend of RNA modifications. The discovery of the significant alteration of the levels of DNA and RNA modifications under alcohol exposure indicates that alcohol consumption may increase the risk of the incidence and development of diseases through dysregulating DNA and RNA modifications.
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.
Colorectal cancer (CRC) is still the leading cause of cancer death worldwide, but the clinical effect of drug therapy such as irinotecan is not an ideal way at present. In recent years, probiotics have attracted much attention, and the combination of probiotics may play an important role in the prevention and treatment of CRC. This work proposed a cellular chip-MS system, to study the synergistic effects of probiotic Lactobacillus rhamnosus GG (L.GG) and irinotecan on HCT116 cells by cell viability and on-line mass spectrometry (MS) analysis. The double-layer chip sandwiched with a polycarbonate membrane can co-culture HCT116 cells and L.GG. And the solid phase microextraction chip can be used for desalination and concentration. Finally, the extracted chemicals were entered the electrospray ionization quadrupole time-of-flight MS to detect irinotecan metabolites. The results showed that with the increasing concentration of co-cultured L.GG, the percentage of living HCT116 cells decreased, but the relative amount of metabolized SN-38 by HCT116 cells increased. Therefore, the microfluidic system can be used to detect and monitor the synergistic effect of irinotecan-L.GG combination on HCT116 cells. In summary, our study provided experimental evidence for the first time with potential applications of irinotecan-L.GG combination in CRC treatment, and the cellular chip-MS system as a powerful tool can be used in the experiments of probiotics as new drugs.
Exosomal microRNA (miRNA) is an ideal candidate of noninvasive biomarker for the early diagnosis of cancer. Sensitive and accurate sensing of abnormal exosomal miRNA plays essential role for clinical promotion due to its close correlation with tumor proliferation and progression. Herein, a microfluidic surface-enhanced Raman scattering (SERS) sensor was proposed for an on-line detection of exosomal miRNA based on rolling circle amplification (RCA) and tyramine signal amplification (TSA) strategy. The microfluidic chip consists of a magnetic enrichment chamber, a serpentine fluidic mixer and a plasmonic SERS substrate functionalized with capture probes. The released miRNA activates the capture probe, triggers RCA reaction, and generates a large number of single-stranded DNA products to drive the catalysis of nanotags deposition via TSA, producing numerous phot spotsq to enhance the SERS signals. In merit of the microfluidics chip and nucleic acid-tyramine cascade amplification, the developed SERS sensor significantly improves the sensitivity for the exosomal miRNA assay, resulting in a limit of detection (LOD) as low as 1 pmol/L and can be successfully applied in the analysis of exosomes secreted from breast tumor cells, which demonstrates the potential utility in practical applications.
In this study, novel iron-doped biochar (Fe-BC) was produced using a simple method, and it was used as an H2O2 activator for tetracycline (TC) degradation. Generally, iron loading can improve the separation performance and reactivity of biochar (BC). In the Fe-BC/H2O2 system, 92% of the TC was removed within 30 min with the apparent rate constant (kobs) of 0.155 min−1, which was 23.85 times that in the case of the BC/H2O2 system (0.0065 min−1). The effects of the H2O2 and Fe-BC dosage, initial pH, and TC concentration on the TC removal were investigated. The radical quenching and electron paramagnetic resonance (EPR) measurements demonstrated that the removal of TC using the Fe-BC/H2O2 process involved both radical (•OH and O2−•) and non-radical pathways (1O2 and electron transfer). In addition, the performance of the catalyst was also affected by the persistent free radicals (PFRs) and defective sites on the catalyst. Moreover, the degradation pathways of TC were proposed according to the intermediate products detected by LC-MS and the ecotoxicity of intermediates was evaluated. Finally, the Fe-BC/H2O2 showed high resistance to inorganic anions and natural organic matter in aquatic environments. Overall, Fe-BC is expected to be an economic and highly efficient heterogeneous Fenton catalyst for removing the organic contaminants in wastewater.
Developing photocatalyst with high activity, superior stability and prominent selectivity for CO2 conversion is of great importance for the target of carbon neutralization. Herein, 3D dahlia-like NiAl-LDH/CdS heterosystem is developed through in-situ decoration of exfoliated CdS nanosheets on the scaffold of NiAl-LDH and the on-spot self-assembly. The formation of a hierarchical architecture collaborating with well-defined 2D/2D interfacial interaction is constructed by optimizing the ratio of CdS integrated in the formation of the heterojunction. The light-harvesting capacity of NiAl-LDH/CdS is improved by this unique scaffold, and the charge transfer between NiAl-LDH and CdS is effectively facilitated by virtue of the unique 2D/2D interface. As a result, the 3D hierarchical NiAl-LDH/CdS heterosystem presents 12.45µmol g−1 h−1 of CO production (3.3 and 1.6 folds of pristine NiAl-LDH and CdS) with 96% selectivity and superior stability. This 3D hierarchical design collaborating with 2D/2D interfacial interaction provides a new avenue to develop ideal catalysts for artificial photosynthesis.
Water-caused luminescence quenching is a well-known and intractable issue for luminescence lanthanide complexes, greatly confining their broad application as sensing and displaying devices in water system. Herein, an anionic and coordination-saturated lanthanide complex with a nanosheet-like structure has been prepared. It exhibits excellent photophysical properties both in solid state and in aqueous suspension. Noteworthily, a 13% improvement for sensitization efficiency from organic ligand to central lanthanide ion has been realized, indicating an exceptional phenomenon of water-induced luminescence improvement which is rarely reported previously. Moreover, the aqueous suspension of as-prepared luminophore could act as a chemo-sensor responding to various organic solvents in water. Both of water-induced luminescence improvement and extended sensing behavior in this work provide a new platform for developing highly performant and practical luminescent materials in the water system.
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