The positions of double bonds in lipids play critical roles in their biochemical and biophysical properties. In this study, by coupling Paternò–Büchi (P‐B) reaction with tandem mass spectrometry, we ...developed a novel method that can achieve confident, fast, and sensitive determination of double bond locations within various types of lipids. The P‐B reaction is facilitated by UV irradiation of a nanoelectrospray plume entraining lipids and acetone. Tandem mass spectrometry of the on‐line reaction products via collision activation leads to the rupture of oxetane rings and the formation of diagnostic ions specific to the double bond location.
Where is the double bond? For the first time, the Paternò–Büchi (P‐B) reaction has been exploited for double‐bond localization in lipids. The P‐B reaction is facilitated by UV irradiation of a nanoelectrospray plume entraining lipids and acetone. Tandem mass spectrometry of the online reaction products by collision activation leads to the rupture of oxetane rings and the formation of diagnostic ions specific to the double‐bond location (see picture).
•Ambient ionization provides high sensitivity for analysis with minimal sample preparation.•Highly quantitative results can be obtained with ambient ionization mass spectrometry analysis.•Miniature ...MS system with atmospheric pressure interface and MS/MS capability have been developed.•Integration of ambient ionization to miniature MS provides promising tools for POC analysis.
Ambien ionization and miniaturization of mass spectrometers are two fields in mass spectrometry that have advanced significantly in the last decade. The integration of the techniques developed in these two fields is leading to the development of complete miniature analytical systems that can be used for on-site or point-of-care analysis by non-expert users. In this review, we report the current status of development in ambient ionization and miniature mass spectrometers, with an emphasis on those techniques with potential impact on the point-of-care (POC) diagnostics. The challenges in the future development of the integrated systems are discussed with possible solutions presented.
Using the statistical data of 280 prefectural-level cities in China from 2011 to 2020, this paper empirically tests the relationship between digital finance and residents' income in a linear and ...nonlinear model based on the G-J model theory, respectively. The study aims to discuss and analyze the impact of digital finance development on income distribution in the context of the current situation of digital finance development in China and further explore how to make digital finance better regulate the income distribution of residents. The innovation of this paper is to use two nonlinear methods to verify the Kuznets effect and threshold characteristics of digital financial development affecting the income distribution of residents based on linear analysis and explore the relationship between n digital economic development the current income gap more comprehensively. The study shows a Kuznets effect of digital finance development on the income distribution of Chinese residents. Thus, most regions in China have not yet crossed the inflection point of the bell-shaped curve, and the income gap within areas will continue to increase with the development of digital finance. By constructing a threshold model, it is found that the positive effect of digital finance on income disparity may initially increase with the increase of regional economic level. Still, when the regional economic development reaches a higher stage, the effect will tend to fall back. As a result, the negative impact of digital finance development on residents' income distribution will be significantly reduced at that time.
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Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Facing severe air pollution, the Chinese government has introduced bottom-up public participation in environmental policy. The increase in public environmental attention can promote the participation ...of all people in environmental governance, which is a major guarantee for achieving the carbon peaking and carbon neutrality goals. In this paper, we use city-year panel data and the strategy of difference in difference (DID) to estimate the impact of environmental regulation of "The Blue Sky Defense War" on public environmental concerns (PEC). This environmental regulation reduces PEC for two reasons. First, the policy has greatly improved air quality in the Beijing-Tianjin-Hebei region and surrounding areas. When air quality improves, people pay less attention to environmental issues. Second, environmental regulations reduce household income. As incomes fall, people will focus more on economic development than on environmental issues.
The presence of carbon–carbon double bonds (CCs) in unsaturated phospholipids is closely related to lipid conformations and physiochemical activities. Previously, we have demonstrated that ...epoxidation reaction facilitated by low-temperature plasma (LTP) enabled the structural analysis of unsaturated fatty acids (FAs). Epoxidation of the CC leads to the production of an epoxide, which can be easily cleaved via collision-induced dissociation (CID) to produce diagnostic ions indicative of the CC bond locations in FAs. In this work, we further developed this method for analysis of phospholipids. Tandem mass spectrometry analysis with epoxidation reaction was performed in both positive and negative ion mode to analyze phosphatidylcholines (PCs), phosphatidic acids (PAs), phosphatidylethanolamines (PEs), phosphatidylglycerols (PGs), and phosphatidylinositols (PIs). The developed method was applied in a shotgun lipidomics approach to characterize phospholipids in a bovine liver extract.
The field of lipidomics has been significantly advanced by mass spectrometric analysis. The distinction and quantitation of the unsaturated lipid isomers, however, remain a long-standing challenge. ...In this study, we have developed an analytical tool for both identification and quantitation of lipid C=C location isomers from complex mixtures using online Paternò–Büchi reaction coupled with tandem mass spectrometry (MS/MS). The potential of this method has been demonstrated with an implementation into shotgun lipid analysis of animal tissues. Among 96 of the unsaturated fatty acids and glycerophospholipids identified from rat brain tissue, 50% of them were found as mixtures of C=C location isomers; for the first time, to our knowledge, the quantitative information of lipid C=C isomers from a broad range of classes was obtained. This method also enabled facile cross-tissue examinations, which revealed significant changes in C=C location isomer compositions of a series of fatty acids and glycerophospholipid (GP) species between the normal and cancerous tissues.
Lack of sensitive single-cell analysis tools has limited the characterization of metabolic activity in cancer stem cells. By hyperspectral-stimulated Raman scattering imaging of single living cells ...and mass spectrometry analysis of extracted lipids, we report here significantly increased levels of unsaturated lipids in ovarian cancer stem cells (CSCs) as compared to non-CSCs. Higher lipid unsaturation levels were also detected in CSC-enriched spheroids compared to monolayer cultures of ovarian cancer cell lines or primary cells. Inhibition of lipid desaturases effectively eliminated CSCs, suppressed sphere formation in vitro, and blocked tumor initiation capacity in vivo. Mechanistically, we demonstrate that nuclear factor κB (NF-κB) directly regulates the expression levels of lipid desaturases, and inhibition of desaturases blocks NF-κB signaling. Collectively, our findings reveal that increased lipid unsaturation is a metabolic marker for ovarian CSCs and a target for CSC-specific therapy.
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•Ovarian cancer stem cells have high levels of unsaturated lipids•Blocking lipid desaturation impairs cancer stemness and tumor initiation capacity•The NF-κB pathway directly regulates the expression of lipid desaturases•Lipid desaturase inhibitors inactivate the NF-κB pathway
Cheng and colleagues using Raman spectroscopic imaging find that ovarian cancer stem cells contain unusually high levels of unsaturated lipids and show evidence that this metabolic difference could be used as a marker for these cells and as a new target for CSC-specific therapy.
The Paternò–Büchi (PB) reaction is a photochemical reaction involving 2 + 2 cycloaddition between electronically excited carbonyl and carbon–carbon double bond (C═C). It has been established as a ...lipid derivatization strategy, leading to confident assignment of C═C locations in lipids when coupled with tandem mass spectrometry (MS/MS). Although acetone and several aryl-containing ketones or aldehydes have been explored as PB reagents, the chemical properties critical to achieving efficient conversion and minimum side reactions remain unclear. Herein, we investigated a set of acetophenone (AP) derivatives, aiming to provide insights into the development of new PB reagents with enhanced performance for lipid analysis. For AP derivatives, we found that electron-withdrawing groups (e.g., −F and −CF3) on the benzene ring improved the overall conversion, while a bulky group at the ortho-position decreased the conversion. Norrish Type I cleavage was largely diminished; however, the Norrish Type II side reaction was more competitive, producing products isomeric to the PB reaction products. Among all AP derivatives tested, 2′,4′,6′-trifluoroacetophenone (triFAP) showed the best performance. It offered a relatively high PB yield (20–30%) for different types of C═C, high sensitivity (sub-nM) for C═C identification, and accurate isomer quantitation. Due to the significantly reduced chemical interferences in shotgun analysis, triFAP provided better performance than that from acetone PB-MS/MS. An offline triFAP PB reaction was implemented in a liquid chromatography analysis workflow, which enabled the large-scale identification of phospholipids including C═C location isomers from a complex lipid extract.
Mass Spectrometry Imaging (MSI) has emerged as a powerful imaging technique for the analysis of biological samples, providing valuable insights into the spatial distribution and structural ...characterization of lipids. The advancements in high-resolution MSI have made it an indispensable tool for single-cell or subcellular lipidomics. By preserving both intracellular and intercellular information, MSI enables a comprehensive analysis of lipidomics in individual cells and organelles. This enables researchers to delve deeper into the diversity of lipids within cells and to understand the role of lipids in shaping cell behavior. In this review, we aim to provide a comprehensive overview of recent advancements and future prospects of MSI for cellular/subcellular lipidomics. By keeping abreast of the cutting-edge studies in this field, we will continue to push the boundaries of the understanding of lipid metabolism and the impact of lipids on cellular behavior.
Oil mobility in liquid-rich shale is crucial for economic success of resource development. The characteristics of the host rock and the properties of oil fluids are two primary factors controlling ...fluid mobility. Organic geochemistry data allows examination of both resource potential and oil mobility. We propose data-driven empirical models in this paper to describe hydrocarbon resource potential with respect to oil mobility. The proposed methods were applied to a dataset collected from the Eocene-Oligocene Es3 and Es4 source rock units in four recent shale oil exploration wells in the Jiyang Super-Depression of the Bohai Bay Basin. The dataset, results from standard programmed pyrolysis of whole rock samples as well as solvent extracted replicates of 139 core samples, was studied to examine the source rock characteristics and shale oil resource potential. Bulk geochemical characteristics and thermal decomposition trends allow for sub-division of the samples into two groups; a) samples with high initial hydrogen index (>800 mg HC/g TOC) and average present day TOC of 4.07% from LY1 and NY1 wells in a distal facies; and b) samples with slightly lower initial hydrogen index (about 700 mg HC/g TOC) and average TOC of 3.11% from FY1 and L69 wells in a transitional facies. Three different categories of oil resource with respect to oil mobility can be defined: adsorbed, restricted and movable based on organic geochemical characteristics and their variations in the stratigraphic intervals represented by the samples in the four wells. We show that expulsion efficiency is a good indicator of hydrocarbon retention in source rock reservoir and that the two wells in the distal facies have higher total resource potentials with abundant movable oil resource than the two wells in the transitional facies. The total oil potential is separated into three types of oil resource to show oil mobility, thus providing more information for business decision.
•Hydrocarbon mobility and retention capacity are crucial in evaluating shale oil resource•Methods are proposed to quantify hydrocarbon retention and mobility in shale resource evaluation•High hydrocarbon retention and better oil mobility associated with distal facies in deep water lacustrine setting
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