Latest ArticlesTrimethoprim (TMP) is a typical antibiotic to treat infectious disease, which is among the most commonly detected antibacterial agents in natural waters and municipal wastewaters. In the present study, the impacts of dissolved oxygen (DO) on the oxidation efficiency and pathways of TMP by reaction with sulfate radicals (SO4·−) were investigated. Our results revealed that the presence of DO was favourable for TMP degradation. Specifically, TMP would react initially with SO4·− via electron-transfer process to form a carbon-centered radical. In the absence of oxygen, the carbon-centered radical could undergo hydrolysis to produce α-hydroxytrimethoprim (TMP−OH), followed by the further oxidation which generated α-ketotrimethoprim (TMP = O). However, in the presence of oxygen, the carbon-centered radical would alternatively combine with oxygen, leading to a sequential reaction in which peroxyl radical and a tetroxide were formed, and finally generated TMP−OH and TMP=O simultaneously. The proposed pathways were further confirmed by density functional theory (DFT) calculations. The results obtained in this study would emphasize the significance of DO on the oxidation of organic micro-pollutants by SO4·−.
Gastric ulcers are one of the most common stomach diseases that often accompanied by inflammation, congestion, edema, scar tissue formation, and pyloric obstruction. Fiberoptic endoscopy and X-ray analysis of the upper GI tract have become the diagnostic procedure of choice for patients. However, conventional diagnosis technology is either invasive or radioactive. Herein, a novel CD-MOF NIR-II fluorophore (GPs-CH1055) was developed. The relative fluorophore intensity was largely consistent at various media and pH buffers, and it can swell into gel particles in solvents and be completely expelled from the gastrointestinal tract without being assimilated. GPs-CH1055 has been further evaluated in vivo, and exhibited strong retention effect on the gastric ulcer sites, bright NIR-II signals with high spatial and temporal resolution. Therefore, GPs-CH1055 shows great promise for realizing real-time gastric ulcer imaging and diagnosis.
Low dimension nano photocatalysts show great potential in the field of treating contaminated water for their large surface area and size effect. In this study, a 0D/1D AgI/MoO3 Z-scheme photocatalyst with striking photocatalytic performance was constructed successfully. The one-dimensional MoO3 nanobelts were prepared by a simple hydrothermal method, and then it was modified by AgI nanoparticles in a handy deposition approach. When choosing sulfamethoxazole (SMZ) as the target contaminant, the rate constant value of the optimal 0D/1D AgI/MoO3 composite could hit up to 0.13 min-1, which is nearly 22.4 times and 32.5 times as that of pure MoO3 (0.0058 min-1) and AgI (0.0040 min-1), respectively. A series of detailed characterizations give evidences that the charge transfer in the composite followed Z scheme mechanism. Therefore, efficient separation/transfer and the remained high redox activity of photogenerated carriers played a vital role in the sharply enhanced photocatalytic properties. The possible degradation pathways of SMZ were proposed based on the intermediates detected by high-performance liquid chromatography-mass spectrometry (HPLC-MS). Meanwhile, the magnificent cyclic stability makes the material a promising material in the practical application.
Polyoxyethylene glycerol ricinoleate (PGR) serves as a solubilizer/emulsifier that is commonly used in pharmaceutical formulations despite being associated with severe anaphylactoid hypersensitivity reactions. Cremophor EL® (CrEL) is the most representative PGR produced from reacting ethylene oxide with castor oil. To help clarify the cause of side effects and potentially improve the safety of PGR-based drug delivery vehicle, we have developed separate but related analytical methods for the quantitation of CrEL and its main metabolites, glycerol ethoxylate (GE) and ricinoleic acid (RA). Since CrEL and GE are highly disperse mixtures of polymers that are not amenable to analysis by conventional liquid chromatography-tandem mass spectrometry (LC-MS/MS), we used liquid chromatography-triple-quadrupole-time-of-flight mass spectrometry (LC-Q-TOF MS) combined with product ion data acquisition by MSALL and sequential window acquisition of all theoretical fragments mass spectrometry (SWATH MS), respectively to perform the analysis. In contrast, RA is a single molecular entity that could be readily analyzed using conventional LC-HR MS/MS. Selection of specific fragment ions for CrEL, GE, RA and their internal standards enabled a precise quantitation of such a complex analytes system in rat plasma after a single and simple sample preparation method. Assay validation indicated linearity for CrEL, GE and RA over the concentration ranges 0.2~20.0 μg/mL, 0.1~10.0 μg/mL and 0.1~20.0 μg/mL, respectively with satisfactory results for other validation parameters. A subsequent pharmacokinetic study involving single intravenous 200 mg/kg injections of CrEL to rats showed the methods enable comprehensive and high throughput quantitation of CrEL and its metabolites in a biological matrix. Our combination of assays provides effective application in investigating the cause of the hypersensitivity reaction of PGR and potentially to improve its safety for using as a vehicle in drug formulations.
In this work, nitric oxide absorption process by using ferrate(Ⅵ)/urea was proposed. The respective influences of the four factors including pH value, ferrate(Ⅵ) concentration, urea concentration, and the temperature and the interactive function of them on nitric oxide absorption were investigated with the response surface methodology (RSM) by central composite design (CCD). The proposed model system showed good consistency with the experiment results, by a correlated coefficient ( R2) of 0.9875. In addition, the interactive influences between any two variables were elaborated through analysis of response surface. The optimal parameters were found at pH of 7.1, reaction temperature of 43.8 ℃, urea concentration of 6.3 wt%, ferrate(Ⅵ) concentration of 4.4 mmol/L for 85.2% NO absorption. Finally, N-containing product analysis shows that nitric oxide was primarily transformed to N2 and NO3−.
Covalent DNA–protein cross-links are toxic DNA lesions that interfere with essential biological processes, which can cause serious biological consequences, such as genomic instability and protein misexpression. 5-Formyluracil (5fU) as an important modification in DNA, which is mainly from oxidative damage, exists in a variety of cells and tissues. We have reported that 5fU mediated DNA–protein conjugates could exist in human cells [Zhou et al. CCS Chem. 2 (2020) 54-63]. We now aimed to explore its potential biological effects in vitro and in vivo. In this paper, we firstly reported that 5fU intermediated DNA–peptide or DNA–protein conjugates (both were called DPCs) could inhibit different polymerases bypass or cause mutations. Then we further investigated the functional impacts caused by 5fU-mediated DPCs, which appeared in different gene expression components [in the promoter sequence or 5′-untranslated regions (UTR)]. These results together may contribute to a broader understanding of DNA–protein interactions as well as the biological functions associated with 5fU.
Carbon nanodots (CDs) based fluorescent nanoprobes have recently drawn much attention in chemo-/bio-sensing and bioimaging. However, it is still challenging to integrate the colorimetric and fluorometric dual readouts into a single CD. Herein, novel hybrid CDs (HCDs) are prepared by a simple microwave-assisted reaction of citric acid (CA), branched polyethyleneimine (BPEI) and potassium thiocyanate (KSCN). As-prepared HCDs show extraordinary properties, including excitation-dependent emission, satisfactory fluorescence quantum yield (46.8%), excellent biocompatibility and optical stability. Significantly, the fluorescence intensity at 450 nm exhibits linear correlation over the Fe3+ concentration from 1 μmol/L to 150 μmol/L with a detection limit (LOD) of 52 nmol/L. Meanwhile, the solution color changes from colorless to orange, and the absorbance at 460 nm increased linearly with Fe3+ concentration ranging from 0.02 mmol/L to 5 mmol/L (LOD: 3.4 μmol/L). All the evidence illustrates that the HCDs can be conditioned for specific Fe3+ sensing with colorimetric and fluorometric dual readouts, which has also been verified with paper-based microchips. The possible mechanism is attributed to the specific interactions between surface functional groups on the HCDs and Fe3+. Additionally, the HCDs are successfully applied in sensing Fe3+ in wastewater and living cells, demonstrating its potential applications in future environment monitoring and disease diagnosis.
Immobilization of enzymes onto carriers is a rapidly growing research area aimed at increasing the stability, reusability and enzymolysis efficiency of free enzymes. In this work, the role of phase-separation and a pH-responsive "hairy" brush, which greatly affected the topography of porous polymer membrane enzyme reactors (PMER), was explored. The porous polymer membrane was fabricated by phase-separation of poly(styrene- co-maleic anhydride-acrylic acid) and poly(styrene-ethylene glycol). Notably, the topography and pores size of the PMER could be controlled by phase-separation and a pH-responsive "hairy" brush. For evaluating the enzymolysis efficiency of d-amino acid oxidase (DAAO) immobilized carrier (DAAO@PMER), a chiral ligand exchange capillary electrophoresis method was developed with d-methionine as the substrate. The DAAO@PMER showed good reusability and stability after five continuous runs. Notably, comparing with free DAAO in solution, the DAAO@PMER exhibited a 17.7-folds increase in catalytic velocity, which was attributed to its tailorable topography and pH-responsive property. The poly(acrylic acid) moiety of poly(styrene- co-maleic anhydride-acrylic acid) as the pH-responsive "hairy" brush generated topography changing domains upon adjusting the buffer pH, which enable the enzymolysis efficiency of DAAO@PMER to be tuned based upon the well-defined architectures of the PMER. This approach demonstrated that the topographical changes formed by phase-separation and the pH-responsive "hairy" brush indeed made the proposed porous polymer membrane as suitable supports for enzyme immobilization and fitting for enzymolysis applications, achieving high catalytic performance.
Electrochemical oxidation of water to produce highly reactive hydroxyl radicals (OH) is the dominant factor that accounts for the organic compounds removal efficiency in water treatment. As an emerging carbon-based material, the investigation of electrocatalytic of water to produce OH on Graphdiyne (GDY) anode is firstly evaluated by using first-principles calculations. The theoretical calculation results demonstrated that the GDY anode owns a large oxygen evolution reaction (OER) overpotential (ηOER=1.95 V) and a weak sorptive ability towards oxygen evolution intermediates (HO*, not OH). The high Gibbs energy change of HO* (3.18 eV) on GDY anode makes the selective production of OH (ΔG=2.4 eV) thermodynamically favorable. The investigation comprises the understanding of the relationship between OER to electrochemical advanced oxidation process (EAOP), and give a proof-of-concept of finding the novel and robust environmental EAOP anode at quantum chemistry level.
Selenium doped carbon (Se/C), an easily fabricated material, was found to be bio-active and it can serve as an adjuvant to enhance the immune effect of Tween 80/Brij 30 (T80/B30) vesicles and Tween 80/polymer cationic surfactant PN320 (T80/PN320) mixed micelles. The synergistic effect of the combination of T80/B30 vesicles and T80/PN320 mixed micelles with Se/C on nasal mucosal immunity was studied in this work, which might provide theoretical basis for developing the related new adjuvant for nasal immunization of recombinant protein, peptide and split protein vaccine. Since both selenium and carbon were bio-compatible elements, Se/C might be safe for practical applications, and this was also reflected by the low hemolytic activity of the materials. This work not only reports an efficient protocol for adjuvant development, but also significantly expands the application scope of selenium chemistry.
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