化学最新文献

Polymers and dendrimers are macromolecules, possessing unique and intriguing characteristics, that are widely applied in self-assembled functional materials, green catalysis, drug delivery and sensing devices. Traditional approaches for the structural characterization of polymers and dendrimers involve DLS, GPC, NMR, IR and TG, which provide their physiochemical features and ensemble information, whereas their unimolecular conformation and dispersion also are key features allowing to understand their transporting profile in confined ionic nanochannels. This work demonstrates the nanopore approach for the determination of charged homopolymers, neutral block copolymer and dendrimers under distinct bias potentials and pH conditions. The nanopore translocation properties reveal that the dispersion and transporting of PEI is pH-dependent, and its capture rate is much lower than that of PAA. The neutral block copolymer with longest molecular chain threads through with longest blockage duration, its highest capture rate was achieved in 0.5 M KCl at pH 5 with slow diffusion and high temporal resolution. The two generations of neutral dendrimers could also translocate under bias potentials, probably due to the ions adsorption on the dendrimers and driven by Brownian force. The TEG-81 with larger molecular size translocates with longer residence time and higher blockage ratio, as expected. Both of the dendrimers exhibit a higher blockage ratio at pH 7.4 than either acidic or alkalic condition, indicating a larger stretched conformation adopted under neutral condition. This work presents the analysis of unimolecular charged and neutral polymers and dendrimers, which will be insightful in understanding the self-assembly motion and transfer of synthetic macromolecules in confined space. It also provides a good indication for deciphering the macromolecule-nanopore interplay under electrophoretic condition.

Hypochlorous acid (HClO/ClO^-) is a common ROS that exhibits elevated activity levels in cancer cells. In this study, an ClO^--triggered TADF probe, PTZ-MNI, was designed based on a naphthalimide core. PTZ-MNI self-assemble in aqueous environments, exhibiting significantly enhanced fluorescence that demonstrated typical aggregation-induced delayed fluorescence (AIDF) characteristics. The probe not only showed high sensitivity to ClO^- but also exhibited remarkable selectivity over other reactive oxygen species and disturbance. PTZ-MNI displayed TADF characteristic, including sensitivity to oxygen in toluene, insensitivity to oxygen in aggregated states that maintain long fluorescence lifetimes, a vertical conformation, and a minimal ΔE_ST of 0.01 eV. Cell imaging studies showed the probe could trace ClO^- by red to green fluorescence in HeLa cell. The colocalization analysis indicated its excellent lysosome-targeting specificity. In addition, PTZ-MNI-O, the compound after oxidation, exhibited effective ROS generation ability and significant PDT effect after irradiation. This work provides guidance for the rational design of responsive TADF luminescent materials used in cell imaging and activatable-PDT.

Emerging contaminants (ECs) pose great challenges to water treatment technology due to their complexity and high harm. In this paper, the method of dielectric barrier discharge (DBD) plasma coupled with iron-based catalyst (FeNC) activating periodate (PI) was first designed for ECs removal. The ingenious introduction of FeNC not only promotes the Fenton-like reaction of DBD system but also reduces the PI activation energy barrier and accelerates the electron shuttle between PI and pollutants. Based on the parameters evaluation of machine learning (ML), the calcination temperature of 575 ℃ and 17 % N addition were determined for best catalytic performance. XRD, Raman spectroscopy, XPS and density functional theory (DFT) analysis show that optimized catalyst has better electron shuttle characteristics and PI activation ability. Compared to DBD (78 %) and DBD/PI (94 %), DBD/FeNC/PI could achieve 100 % degradation efficiency of sulfadiazine (SDZ) in 12 min with high reaction rate. In addition to the effects of ROSs (¹O₂, OH and O₂^-), the efficient electron transfer mediated by FeNC and PI is the key to promoting the degradation of pollutants. The progressive dissociation of pyrimidine ring under the action of OH and electron transfer is the main pathway of SDZ degradation. The toxicity of intermediate products produced by the system is generally lower than that of SDZ. The system still has a high SDZ removal efficiency in actual water and has a good removal effect for other types of ECs, which also makes the system have a better practical prospect.

Graphitic carbon nitride (g-C₃N₄) has been regarded as highly potential photocatalyst for solar energy utilization. However, the restricted absorption of visible light for pristine g-C₃N₄ significantly limits the solar-light-driven chemical reaction efficiency. Herein, structurally distorted g-C₃N₄ nanosheets with awakened n-π* electron transition were successfully synthesized through hexamethylenetetramine (HMTA)-involved supercritical CO₂ (scCO₂) treatment and following pyrolysis of melamine precursor. ScCO₂ treatment was conductive to homogeneously dissoving melamine precursor and HMTA, and then the modification by HMTA with three-dimensional structure changed the g-C₃N₄ photocatalyst from a symmetrical planar structure to an asymmetrical non-planar structure. The resulting awakened n-π* electron transition in structurally distorted g-C₃N₄ nanosheets greatly extended the photoresponse range of g-C₃N₄ and increased the amount of catalytically active π electrons. Moreover, the unique distorted structure of g-C₃N₄ enhanced photogenerated charge carriers separation and provided sufficient reactive sites for photocatalytic H₂ production. Consequently, the structurally distorted g-C₃N₄ nanosheets exhibited enhanced photocatalytic H₂ production performance, which was up to 6.4 times that of pristine g-C₃N₄. This work presents a promising scCO₂ strategy towards precursor treatment to regulate the microstructure of g-C₃N₄, and provides valuable guidance to obtain efficient g-C₃N₄ photocatalyst by microstructure engineering.

Developing insertion-type anodes is essential for designing high-performance "rocking chair" zinc-ion batteries. BiOCl shows great potential as an insertion-type anode material for Zn²⁺ storage due to its high specific capacity and unique layered structure. However, the development of BiOCl has been significantly hampered by its poor stability and kinetics during cycling. In this study, Br-doped and carbon-coated BiOCl ultrathin nanosheets (Br-BiOCl@NC) are synthesized as high-performance anodes. The ultrathin nanosheet morphology facilitates Zn²⁺/H⁺ transfer and the Br doping reduces the Zn²⁺/H⁺ diffusion barrier. Additionally, the carbon coating enhances the electronic transfer. Furthermore, an insertion-conversion mechanism involving H⁺ and Zn²⁺ storage is revealed by ex-situ tests. Therefore, Br-BiOCl@NC exhibits a high discharge capacity of 174 mA h/g at 500 mA/g without capacity degradation after 1000 cycles. The Br-BiOCl@NC//MnO₂ full cell presents a discharge capacity of ≈ 120 mA h/g at 200 mA/g. This work offers valuable insights for the design of high-performance insertion-type anode materials in zinc-ion batteries.

Spatial metabolomics offers the combination of molecular identification and localization. As a tool for spatial metabolomics, mass spectrometry imaging (MSI) can provide detailed information on localization. However, molecular annotation with MSI is challenging due to the lack of separation prior to mass spectrometric analysis. Contrarily, surface sampling capillary electrophoresis mass spectrometry (SS-CE-MS) provides detailed molecular information, although the size of the sampling sites is modest. Here, we describe a platform for spatial metabolomics where MSI using pneumatically assisted nanospray desorption electrospray ionization (PA-nano-DESI) is combined with SS-CE-MS to gain both in-depth chemical information and spatial localization from thin tissue sections. We present the workflow, including the user-friendly setup and switching between the techniques, compare the obtained data, and demonstrate a quantitative approach when using the platform for spatial metabolomics of ischemic stroke.

Bacterial bloodstream infections cause high morbidity and mortality. Although bacteria can be detected by various methods, culture methods are often used for the detection of live, accurate, reproducible, and selective bacterial identification. However, the culture method is time-consuming, and clinicians often start treatment immediately due to the long determination time. This reduces the bacterial density detectable by culture, and in some cases, makes determination difficult. To overcome this challenge, we propose a method that directly combines bacteriophage-based lysis with quantitative PCR (qPCR). This method enables the simple and rapid detection of bacteria without the need for pre-concentration or DNA extraction steps. Escherichia coli K12 (E. coli K12) was used as the model bacterium, and bacteria lysed by the E. coli K12-specific bacteriophage were detected using qPCR. The total analysis time was less than 3 h, and only live bacterial cells were selectively lysed. The method was also used to detect bacteria spiked into reference plasma samples, and bacterial DNA was detected via qPCR. The results obtained from the calibration graph created with cultured bacteria and the one created by spiking bacteria into reference plasma were consistent. The similarities between the calibration graphs from both methods were found to be in the range of 92-102.7 %. The LOD and LOQ values for bacteria spiked into reference plasma were calculated as 14.80 and 3.5x10³ CFU/mL, respectively.

Near-infrared (NIR) spectroscopy analysis technology has become a widely utilized analytical tool in various fields due to its convenience and efficiency. However, with the promotion of instrument precision, the spectral dimension can now be expanded to include hundreds of dimensions. This expansion results in time-consuming modeling processes and a decrease in model performance. Hence, it is crucial to carefully choose representative features before constructing models. This paper focuses on the limitations of filter algorithms, which can only sort features and cannot directly determine the best subset of features. A hybrid method of combination of the Max-Relevance Min-Redundancy (mRMR) algorithm and the Genetic Algorithm (GA), as well as filter and wrapper feature selection methods, are combined to select appropriate features automatically. This hybrid algorithm retains the features in each individual that are considered to have a strong correlation and low redundancy by the mRMR algorithms during each iteration of the GA. On the other hand, it deletes the features that are regarded as having little correlation or high redundancy. Through the process of iteration, the feature subset is continuously optimized. We use the proposed hybrid method to select features on two datasets and establish various models to verify our proposed method in this paper. The experimental results indicate the feature selection approach, which combines mRMR with the GA, covers the advantages of both feature selection methods. This approach can select features that show good predictive performance. When compared with other common feature selection methods, such as the Uninformative Variable Elimination algorithm (UVE), Competitive Adaptive Reweighted Sampling algorithm (CARS), Successive Projections Algorithm (SPA), Iteratively Retains Informative Variables (IRIV), and GA, the hybrid algorithm can select a larger number of feature variables that are both representative and informative, additionally, it significantly enhances the predictive performance of the model.

Accurately detecting cysteine (Cys) in vivo is crucial for diagnosing Cys-related diseases. A novel ratiometric fluorescent probe featuring dual near-infrared emission is developed in this study for the in vivo ratio imaging of Cys. The probe comprises a hemicyanine organic small-molecule dye (HCy-CYS) with specific Cys recognition capabilities covalently coupled with carbon dots (CDs) synthesized using glutathione (GSH) as the carbon source (GCDs), forming a unique composite nanofluorescent probe (GCDs@CYS). The probe undergoes a specific reaction with acrylate upon the addition of Cys, converting HCy-CYS to HCy-OH. Consequently, the GCD fluorescence intensity at 685 nm gradually decreases, whereas that of HCy-OH at 720 nm progressively increases, yielding a ratiometric fluorescence signal. Notably, both emission wavelengths of the probe exceed 650 nm, thereby effectively mitigating the interference from background signals during cellular and in vivo imaging. Furthermore, the probe demonstrates high specificity for Cys, enabling its differentiation from homocysteine and GSH. The Cys concentration and fluorescence ratiometric intensity exhibit a strong linear correlation at 10-150 μM with a detection limit of 0.95 μM. These results indicate that the ratiometric fluorescent probe can serve as a valuable tool for monitoring Cys-related physiological or pathological processes.

Pursuing nanomaterials with high fluorescence quantum yields is of great significance in the fields of bioimaging, medical diagnosis, and food safety monitoring. This work reports on orange-emitting aggregation-induced emission (AIE) copper nanoclusters (Cu NCs) integrated with blue-emitting nitrogen-doped carbon dots (N-CDs), which enables highly sensitive detection of S^2- and Zn²⁺ ions through an off-on ratiometric fluorescence method. The highly emissive Cu NCs was doped by Ce³⁺ with a high quantum yield of 51.30 % in aqueous solution. The S^2- can induce fluorescence quenching of AIE Cu NCs/N-CDs from orange to blue, while Zn²⁺ can restore the orange fluorescence. The probe provided linear detection ranges of 0.5-170 μM for S^2- and 0.05-200 μM for Zn²⁺, with detection limits of 0.17 μM and 0.02 μM, respectively. Moreover, a smartphone assistant ratiometric fluorescent test strips were developed for the rapid and visual detection of S^2- and Zn²⁺. The AIE Cu NCs/N-CDs probe exhibited diverse fluorescence color responses, high fluorescence stability, and low cytotoxicity. The ratiometric system was successfully applied to the detection of S^2- and Zn²⁺ in real water samples as well as in cellular and living imaging, demonstrating its potential in biochemical analysis and food safety monitoring.