化学最新文献

The dried matrix spot (DMS) method, initially developed for neonatal blood screening, has gained prevalence in various research fields for its efficiency in handling small sample volumes and its adaptability to diverse analytical techniques. This study presents the results of the first systematic investigation of direct multi-element analysis in DMS of human blood and plasma samples with Particle Induced X-ray Emission (PIXE). Internal standard addition was used to address the issue of DMS heterogeneity and to eliminate the need for determining the sample volume equivalent, allowing a single-spot (single-punch) measurement. The method was tested for linearity, accuracy, precision and limit of detection (LOD) using reference materials. It was applied to samples from healthy volunteers and compared to analysis results obtained by ICP-OES showing good agreement. Sample volumes as low as 50 μL were sufficient for the quantification of Na, Mg, P, S, K, Ca, Fe, and Zn in whole blood, and Na, Mg, P, S, K, and Ca in plasma samples without significant matrix effects being observed. Chlorine, which is also an electrolyte element present in high enough concentrations for determination by PIXE, was not addressed in this study due to a lack of reference materials. The results highlight PIXE as a viable alternative to other techniques that are sensitive to matrix issues, require larger sample volumes and/or sample treatment. Overall, this work establishes DMS sampling as being suitable for direct multi-element analysis of biological samples by PIXE, offering detection limits at the mg/L level which is sufficient for determination of electrolyte and essential trace elements and paving the way for its broader application in clinical and research settings.

As a novel carbon-based material with two-dimensional (2D) characteristics, graphdiyne (GDY) shows great potential in constructing active catalytic sites due to its distinctive atomic configuration and sp/sp² conjugated hybrid two-dimensional networks. In this study, the layered GDY was synthesized using the ball milling method, and Zn_0.5Cd_0.5S/Graphdiyne/NiO (ZnCdS/GDY/NiO) composite was synthesized by in-situ composite and physical mixing method. The prepared ZnCdS/GDY/NiO has good photostability outstanding performance in photocatalytic hydrogen production. When exposed to 5 W of white light, the ZnCdS/GDY/NiO photocatalyst demonstrates a hydrogen production rate of 24.44 mmol·g^-1·h^-1, which was 8.4 times greater than that of pure Zn_0.5Cd_0.5S under the same conditions. Various characterization tests and theoretical calculations show that the improved photocatalytic efficiency resulted from the formation of a dual S-scheme heterostructure in the ZnCdS/GDY/NiO composite catalyst, which promoted the recombination of relatively useless photogenerated electron holes. Furthermore, strong photogenerated holes and electrons in the more positive valence band (VB) and the more negative conduction band (CB) were retained, which significantly improved the photogenerated carrier separation ability of the composite catalyst, and thus enhances the hydrogen evolution activity.

The growing modern industry has promoted the development of gas sensors for environmental monitoring and safety checks. However, the traditional chemical resistance gas sensor still has some disadvantages such as high power consumption and limited detection, mainly due to the lack of charge transfer ability of sensing materials. In this paper, an ordered UV-activated gas sensor with mesoporous ZnO/TiO₂ nanotube composite was prepared by precisely controlling the growth of ZnO on the inner wall of TiO₂ nanotube. Based on the synergistic effect of Knudsen diffusion, photoactivation, and in situ heterojunction amplification, the charge transfer performance under room temperature of ZnO/TiO₂ nanotube composites is improved. Compared to TiO₂ nanotube sensor, the ZnO/TiO₂ sensor has a 10-fold enhanced response to NO₂, and the detection limit is as low as 50 ppb. Moreover, we studied the performance of ZnO/TiO₂ sensor on NO₂ in campus, street entrance and chemical plant, and comparing with commercial sensor, found that the detection error and detection limit of our sensor is lower, which proves the sensor has great application prospect in practical detection. This work provides a successful method for in-situ construction of ordered mesoporous materials and gives a solution for the design of advanced photoelectric gas sensors.

This study reports the development and implementation of a straightforward, rapid, and cost-effective voltammetric technique for piroxicam (PIR) detection at nanomolar concentrations in biological and environmental samples. The method involved the use of a screen-printed electrode (SPE) enhanced with a combination of Printex L6 carbon (PL6C) and polyaniline-based activated carbon (PAC) on a chitosan film crosslinked with epichlorohydrin (CTS:EPH). The detection was carried out using square-wave adsorptive anodic stripping voltammetry (SWAdASV) in a 0.10 mol L^-1 phosphate buffer solution at pH 6.0. The approach employed yielded a low limit of detection of 4.5 × 10^-9 mol L^-1 and a linear range of 5.0 × 10^-8 to 8.8 × 10^-6 mol L^-1 (r = 0.999). The PAC-PL6C-CTS:EPH/SPE sensor was effectively employed for PIR detection in synthetic urine and river water samples, where its reliability was proven through addition and recovery tests. The results obtained from the application of the proposed voltammetric method closely matched those recorded under high-performance liquid chromatography (HPLC), which was used as a reference method. The findings show that the technique proposed in this study offers a simple, quick, and highly effective alternative mechanism for PIR detection in both biological and environmental matrices.

The purpose of this study was to investigate the predictive value of mitochondrial oxidative stress-related LncRNA in cancer prognosis and immunotherapy response, and to further analyze the molecular structure of ribosomal protein L34 and its interaction mechanism with the protein. We screened lncrnas associated with mitochondrial oxidative stress, evaluated their expression patterns in different cancer types, and analyzed the three-dimensional structure of ribosomal protein L34 and its interaction network with other proteins. In this study, public databases were used to screen out lncrnas associated with mitochondrial oxidative stress. Bioinformatic analysis, including gene expression profile analysis, survival analysis and functional enrichment analysis, was used to evaluate the expression patterns of these lncrnas in different cancer types and their relationship with prognosis. The interacting proteins of ribosomal protein L34 were identified by proteomic techniques. The three-dimensional structure of ribosomal protein L34 and its binding mode with interacting proteins were studied by molecular docking and dynamic simulation methods. The results showed that the screened lncrnas showed significant expression differences in multiple cancer types and were closely related to the survival rate of patients. The three-dimensional structure of ribosomal protein L34 reveals key amino acid residues and binding sites for its interactions with specific proteins. Functional enrichment analysis showed that these lncrnas may affect the development of cancer through regulating oxidative stress response, cell cycle and apoptosis. The interaction network of ribosomal protein L34 reveals its central role in protein synthesis and cellular stress response.

This study identified the amino acid sequences of peptides generated from the enzymatic hydrolysis of goat milk proteins from two different sources and annotated their functional activities. Peptidomics and molecular docking approaches were used to investigate the antioxidant and ACE inhibitory properties of the unique peptides, revealing the molecular mechanisms underlying their bioactivity. In vitro experiments showed that the IC50 values for ACE inhibition of the four peptides (LSMTDTR, QEALELIR, NIPVGILR, and QAQNVQHY) were 2.087, 7.584, 2.845, and 4.884 mg/mL, respectively, while the IC50 values for DPPH radical scavenging were 4.466, 4.496, 4.626, and 3.875 mg/mL, respectively, indicating strong antioxidant and ACE inhibitory potential. These findings suggest that goat milk protein could serve as a promising natural source of bioactive peptides with therapeutic potential for managing oxidative stress and hypertension.

Linear dextrin (LD), a low-molecular-weight carbohydrate, regarded as a type of short amylose, can form resistant starch when combined with fatty acids. This study investigated the structural properties and in vitro digestion of linear dextrins and their complexes with lauric acid (LA). Four groups of linear dextrins were prepared by pretreating gelatinized high-amylose maize starch (HAMS) with pullulanase followed by gradient ethanol precipitation at concentrations of 0 %, 50 %, 60 %, and 70 % (v/v). The GPC results showed that the weight average molecular weight (M_w) of these linear dextrins were 425.88 kDa, 189.68 kDa, 3.77 kDa and 2.01 kDa, respectively. After linear dextrins were complexed with lauric acid through co-precipitation treatment, the X-ray diffraction data revealed that, except for LD-70-LA, all other complexes formed a V-type structure. The complexing index of the complexes initially increased and then declined with increasing ethanol concentration, reaching a peak value of 41.54 % for LD-50-LA. The LD-0-LA, LD-60-LA and LD-70-LA complexes exhibited weaker anti-digestion properties compared to LD-50-LA, which demonstrated the highest resistant starch content at 52.43 %. This study offers a new approach and application potential for the efficient production of resistant starch.

The development of bio-based flame retardants has garnered significant attention, however, significant challenges remain in achieving efficient flame retardancy and eco-friendly preparation methods. Herein, we propose a facile, atomic-efficient, and eco-friendly strategy for synthesizing a trinity chitosan-based flame retardant, phosphite-protonated chitosan (PCS). The chemical structure was systematically analyzed and the impact of varying degrees of protonation on the dissolution behavior and rheological properties were investigated. Benefiting from the promotion of dehydration and carbonization facilitated by phosphite groups, PCS exhibits high intrinsic flame retardancy with an LOI value of 80.7 %. Moreover, its favorable rheological and film-forming properties make it well-suited for easy application as a multifunctional coating in fabric finishing through blade coating processes. The finished cotton and polyester/cotton blended fabrics exhibit excellent flame retardancy, as evidenced by increased LOI values, successful passage of vertical burning tests, reductions of up to 65.0 % and 50.3 % in pHRR and THR values, respectively. Additionally, PCS imparts superior antibacterial properties to the fabrics, achieving a 99.99 % antibacterial rate against both E. coli and S. aureus. This study introduces a straightforward and atom-economical approach for preparing highly efficient chitosan-based flame retardants, along with the development of a transparent, green, and efficacious multifunctional coating system on textiles.

Chemotherapy serves as the primary treatment for cancers, facing challenges due to the emergence of drug resistance. Combination therapy has been developed to combat cancer drug resistance, yet it still suffers from lack of specific targeting of cancer cells and poor accumulation at the tumor site. Consequently, targeted administration of chemotherapy medications has been employed in cancer treatment. Doxorubicin (DOX) is one of the most frequently used chemotherapeutics, functioning by inhibiting topoisomerase activity. Enhancing the anti-cancer effects of DOX and overcoming drug resistance can be accomplished via delivery by nanoparticles. This review will focus on the development of peptide-DOX conjugates, the functionalization of nanoparticles with peptides, the co-delivery of DOX and peptides, as well as the theranostic use of peptide-modified nanoparticles in cancer treatment. The peptide-DOX conjugates have been designed to enhance the targeted delivery to cancer cells by interacting with receptors that are overexpressed on tumor surfaces. Moreover, nanoparticles can be modified with peptides to improve their uptake in tumor cells via endocytosis. Nanoparticles have the ability to co-deliver DOX along with therapeutic peptides for enhanced cancer treatment. Finally, nanoparticles modified with peptides can offer theranostic capabilities by facilitating both imaging and the delivery of DOX (chemotherapy).

Metamorphic proteins switch reversibly between distinctly different folds often with different functions under physiological conditions. Here, the kinetics and thermodynamics of the fold-switching at different temperatures in a metamorphic protein, KaiB, involved in cyanobacterial circadian clock, reveal that enthalpy-driven the fold-switching to form fold-switched KaiB (fsKaiB) and the fsKaiB and ground-state KaiB (gsKaiB) are more dominantly at lower and higher temperatures, respectively. Thermodynamic analysis indicates that conformational and solvent entropy have opposing effects on KaiB's fold-switching. The folding kinetic reveals that as KaiB folds, it preferentially folds into gsKaiB and then switches fold to fsKaiB. Temperature-sensitive protein fold-switching can be further extended into applications, such as new temperature-sensitive molecular switcher and biosensors development.