化学最新文献

A robust interface for coupling capillary electrophoresis (CE) to mass spectrometry (MS) was critical to maintain high separation efficiency of CE while achieving high sensitivity of MS. Current interfaces often suffer from problems such as reproducibility and ruggedness. For this purpose, a new polymetallic-coated sheathless interface was developed for the coupling of CE with MS. The electrical contact of the interface was achieved by etching one end of the fused silica capillary into a tapered tip using hydrofluoric acid (HF) solution, and then depositing a thin layer of chromium followed by a layer of platinum on it via physical vapor deposition technique. The performance of the new sheathless interface was systematically evaluated for the effect of flow rate and electrospray ionization (ESI) voltage on MS signal intensity, as well as the sample loading volume on CE separation efficiency and repeatability by using peptide standards and tryptic digest of bovine serum albumin (BSA). The interface was capable of generating stable electrospray even at ultra-low flow rate of 12.2 nL/min. In addition, the acid and alkali resistance of the polymetallic-coated emitter was tested by immersing it into 1 M HCL and 1 M NaOH solution, respectively. The results showed that polymetallic coating was still intact even after continuous immersion in the alkaline solution for 8 days (192 h) and a longer period in the acidic solution, indicating its excellent chemical stability. All the experimental results indicated that the sheathless interface fabricated by the new method in this study was robust and stable, making it promising for both sensitive and robust CE-MS sample analysis.

Cysteine (Cys) is involved in many physiological processes. It's challenging to detect Cys selectively as it has similar chemical structure with other biothiols such as homocysteine (Hcy) and glutathione (GSH). In this work, a novel fluorescence probe toward mitochondrial cysteine, HPXI-6C, has been developed by employing carbonate as a new recognizing unit and hemicyanine as a chromophore. HPXI-6C exhibits a high selectivity to Cys over hydrogen sulfide, homocysteine and glutathione. The limit of detection toward Cys was determined to be 42 nM. HPXI-6C can localize in mitochondria and produce strong fluorescence peaked at 725 nm in response to Cys in tumor cells. The uptake and generation pathways of Cys in acetaminophen hepatotoxicity cells was revealed by using HPXI-6C. HPXI-6C has been successfully applied in imaging of Cys in drug-induced liver injury in vivo. The research demonstrated that HPXI-6C is powerful in monitoring Cys and is conducive to the early diagnosis of drug-induced liver injury diseases.

Herein, we report a fast (10 min) and simple surface treatment of pure carbon cloth (CC) only by an air plasma. The structural characterizations indicate that the air plasma process brings out higher rugosity, more defects, and increased oxygen-related groups on CC surfaces than Ar- or N₂-plasma, which can offer abundant capture sites, large electroactive area, and superhydrophilic interface for analytes. As a result, the air-treated CC (CC-P_Air) electrode achieves a pronounced improvement of electrocatalytic activity for the [Fe(CN)₆]^3-/[Fe(CN)₆]^4- probe evidenced by increased peak currents, decreased peak-to-peak separation, and the lowered resistance of charge transfer. It is also demonstrated that the self-supported CC-P_Air electrode possesses excellent sensing performance toward dopamine (DA) and uric acid (UA). The feasibility of the simultaneous electrochemical detection of DA and UA can be verified by their large peak potential gap (∼112 mV) for differential pulse voltammetry. The chronoamperometric sensor yields wide linear ranges of 0.05-100 μM for DA and 0.5-300 μM for UA. The corresponding detection limits are estimated to be 2.6 and 20.4 nM for DA and UA, respectively. The sensor also displays satisfactory selectivity, stability, and reproducibility. Due to good flexibility, the CC-P_Air electrode presents great potential for manufacturing wearable and soft electronics for human health monitoring.

Ligustri Lucidi Fructus (LLF) is a traditional Chinese medicine (TCM) to treat hepatopathy and osteopathy. Wine-processed LLF (WLLF) was much more widely used than raw LLF (RLLF) in clinical practice, however, there is no consensus on processing time. To investigate the processing status of WLLF and transformation rules during processing, a UHPLC-Q-Orbitrap-MS method combined with data-independent acquisition (DIA) mode was firstly established and 227 compounds were identified or tentatively identified. Subsequently, a novel strategy using integration weighted gene co-expression network analysis (WGCNA) with LC-MS data was proposed. A total of 73 differential metabolites were screened out between RLLF and WLLF (wine steaming for 18 h). Meanwhile, the concentration of 11 differential compounds for WLLF was quantified. Finally, correlations between compounds were analyzed by WGCNA and the top five compounds negatively correlated with salidroside were validated, revealing that G13, specnuezhenide, oleuropein, acteoside, and neonuzhenide could be transformed into salidroside and its analogues during processing, respectively. The results indicated that our proposed strategy could be effectively employed to evaluate the processing status of TCMs.

Lipids contribute to atherosclerotic cardiovascular disease but their roles are not fully understood. Spatial lipid composition of atherosclerotic plaques was compared between species focusing on aortic plaques from New Zealand White rabbits and carotid plaques from humans (n = 3), using matrix-assisted laser desorption/ionization mass spectrometry imaging. Histologically discriminant lipids within plaque features (neointima and media in rabbits, and lipid-necrotic core and fibrous cap/tissue in humans) included sphingomyelins, phosphatidylcholines, and cholesteryl esters. There were 67 differential lipids between rabbit plaque features and 199 differential lipids in human, each with variable importance in projection score ≥1.0 and p < 0.05. The lipid profile of plaques in the rabbit model closely mimicked that of human plaques and two key pathways (impact value ≥ 0.1), sphingolipid and glycerophospholipid metabolism, were disrupted by atherosclerosis in both species. Thus, mass spectrometry imaging of spatial biomarkers offers valuable insights into atherosclerosis.

In this work, a novel deep eutectic solvent (DES) composed of thymol and 1-(o Tolyl)thiourea 9/1 (mol) is presented for the first time. This DES has not been described in the literature. This DES was first used as a stationary phase in an extraction column integrated into a flow injection analysis system for the simultaneous determination of mercury and copper in edible oils. The automated approach involves passing an aqueous sample solution obtained after microwave mineralization through a microcolumn of DES retained on polytetrafluoroethylene. This leading to the extraction and concentration of the analytes. The metals are then eluted with an aqueous thiourea solution for subsequent analysis by inductively coupled plasma-optical emission spectrometry. The limits of detection (LODs) for mercury and copper were 3 μg L⁻¹ and 2.5 μg L⁻¹, respectively. The approach demonstrated high accuracy. Relative standard deviations (RSD) for repeatability and inter-day reproducibility ranged from 3 % to 11 %. Extraction recovery of both metals exceeded 95 %, indicating the high efficiency of the DES-based extraction process. Environmental assessment using the AGREEprep method yielded a favorable environmental index of 0.54, highlighting the robustness of the approach. This novel use of DES as a stationary phase in flow injection analysis system provides a robust, efficient and environmentally friendly approach to the determination of trace metals in edible oils. This method can also be applied to the analysis of other samples.

Illicit drugs are a global burden, not only for society, but also for the various control authorities for which its rapid on-site detection remains a challenge. In this context, the potential of a voltammetric electronic tongue (ET) for the analysis of different drugs is evaluated herein. Concretely, the discrimination and identification of cocaine, heroin, 3,4-Methylenedioxymethamphetamine (MDMA), methamphetamine and ketamine in self-prepared and real samples were attempted. For its analysis, an array of three carbon-based screen-printed electrodes (SPE) was prepared, and their responses towards the different drugs and some of the more common cutting agents and adulterants were assessed by means of square wave voltammetry (SWV). To this aim, a tiny amount (ca. 3 mg) of the drug powder was added to the electrochemical cell containing phosphate buffer (pH 12), shaken, and measured directly without any other pre-treatment than its dilution. Next, to identify their characteristic fingerprint, obtained voltammograms were submitted to linear discriminant analysis (LDA), which allowed to correctly identify the different drugs regardless of the presence of the different cutting agents and other possible interfering compounds, or their concentration. Satisfactory results were obtained both for the synthetic and the "street" seized samples, with a classification rate of 100 % for the external test subset of the latter (n = 10).

The present study examines the extent to which a two-factor model of affect explains how caregiving appraisals experienced by caregivers influence their own well-being. We used data from three waves of Nation Study of Caregiving (NSOC) to conduct latent growth curve models with the time-varying predictors to investigate the effect of between-person (BP) and within-person (WP) caregiving appraisals on positive and negative affect. Furthermore, we simultaneously modeled WP differences in activity participation and affective experience with multilevel modeling. Then, we tested the moderating effect of activity participation in the association between WP caregiving appraisals and emotional valence. We found that BP and WP caregiving negative appraisal also contribute to caregiver positive affect similar to that of negative affect. Time-varying effects of negative appraisals and emotional valence are consistent with the two-factor model. Future longitudinal investigations could target WP and BP activity participation to alleviate caregiving cognitive appraisal among caregivers.

Ensuring the detection sensitivity of both RNA-derived and DNA-derived target genes in a single reaction has posed a significant challenge for on-site detection of plant pathogens. This challenge was addressed by developing a one-tube dual RT-RAA assay combined with LFS for the rapid on-site detection of pepper mild mottle virus (PMMoV) and four Colletotrichum species causing anthracnose in Solanaceous crops. By testing four different combinations of primer groups, two combinations were precisely adjusted within the dual RT-RAA system to balance amplification efficiency and maintain consistent levels of amplification in crude plant samples. Utilizing commercially accessible small-scale equipment and following a streamlined optimization strategy, the assay achieved a limit of detection of 0.32 copies/μL of target genes in the reaction. Importantly, it demonstrated no cross-reactivity with other plant pathogens, thereby affirming the high sensitivity and specificity of the developed dual RT-RAA-LFS detection assay. Moreover, the entire process took only 25 min from sample collection to the visible presentation of results. The assay was validated with 60 field samples and 10 seed samples, producing results consistent with reverse transcription quantitative polymerase chain reaction (RT-qPCR). Notably, it successfully detected PMMoV in systemic leaves without visible symptoms three days post-inoculation, underscoring its effectiveness in early disease detection. This streamlined strategy offers a valuable approach for rapid, low-cost, and highly sensitive on-site simultaneous detection of RNA genome-contained PMMoV and DNA genome-contained Colletotrichum species.