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Direct profiling of endogenous biomolecules in tissue samples is considered as a promising approach to investigate metabolic-related toxicity in organisms induced by emerging pollutants. Herein, we report the application of internal extractive electrospray ionization mass spectrometry (iEESI-MS) to direct phospholipid profiling in the liver and spleen tissues of Nile tilapia exposed to perfluorooctanoic acid (PFOA). Combining positive and negative ion detection modes, 130 phospholipid signals were directly detected and identified by iEESI-MS in the tissues of Nile tilapia, including phosphatidyl cholines (PCs), sphingomyelins (SMs), phosphatidic acids (PAs), phosphatidyl ethanolamines (PEs), phosphatidyl glycerols (PGs), phosphatidyl inositols (PIs) and phosphatidyl serines (PSs). With the help of partial least squares discriminant analysis (PLS-DA) and one-way analysis of variance (ANOVA), several phospholipid signals showed a significant difference in the tissue of Nile tilapia between the control group and PFOA exposure groups. In addition, pathway analysis revealed that PFOA has a significant metabolic impact on the glycerophospholipid metabolism in Nile tilapia. Without complex sample preparation, iEESI-MS was applied to direct phospholipid profiling in the liver and spleen tissues of Nile tilapia treated with PFOA, which provided a promising methodology for investigating environmental toxicity and phospholipid-dysregulation caused by emerging pollutants in aquatic organisms. [ABSTRACT FROM AUTHOR]

The wide application of nano-particles (NPs) has raised a serious concern over their impact on plants. However, evaluation of the effects of NPs on plant metabolism by direct detection of chemicals inside solid tissues presents a challenge. In this study, we report on a direct ionization method in mass spectrometry, internal extractive electrospray ionization (iEESI), for the direct evaluation of phytotoxicity of three different NPs (including CdTe quantum dots (CdTe QDs), gold nano-particles (Au NPs), and silver nano-particles (Ag NPs)) both on surfaces and inside solid tissues from the mung bean seeds (Vigna radiata) that were cultured in aqueous solutions of three NPs at 50 μg mL−1. The results showed that NPs could stimulate the biological accumulation of trigonelline and the decomposition of polysaccharides/oligosaccharides to glucose and maltose within 21 h of culture. To the best of our knowledge, this is the first study to apply internal extractive electrospray ionization mass spectrometry (iEESI-MS) for the direct measurement of solid tissue samples to evaluate the phytotoxicity of NPs on mung bean sprouts. Our study lays a solid foundation for further examination of other NPs-induced damaging effects such as apoptosis/necrosis, helping us to understand the phytotoxicity of NPs on plants. [ABSTRACT FROM AUTHOR]

Exploring the metabolic disturbance of fipronil and its derivatives in aquatic organisms may provide a more comprehensive understanding of the impact of fipronil on the ecological environment. In this work, internal extractive electrospray ionization mass spectrometry (iEESI-MS) was used to directly analyze metabolites in the liver tissue of zebrafish exposed to fipronil and its three derivatives. Partial least squares-discriminant analysis (PLS-DA) revealed that 32 signals were considered as differential signals in zebrafish after the exposure treatment of fipronil and its derivatives, including phosphatidylcholines (PCs), lysophosphatidylcholines (LPCs), phosphatidylethanolamines (PEs), fatty acids and so on. The pathway analysis result showed that both fipronil and its derivatives have a significant impact on the glycerophospholipid metabolism of zebrafish. Besides, the intensities of PC signals in the liver samples of each group showed such a trend: mixed fiprole exposed group > fipronil sulfone exposed group ≈ fipronil sulfide exposed group > fipronil exposed group > fipronil desulfinyl exposed group > control group, indicating that mixed exposure of fipronil and its derivatives exhibited more significant metabolic disturbance in zebrafish. Taken together, iEESI-MS is applied to environmental toxicology and investigating the metabolic disturbance induced by fipronil and its derivatives in aquatic organisms, providing a new analytical method for this field. [ABSTRACT FROM AUTHOR]

Phospholipids in microvolume biofluid samples (≤0.5 μL), including human plasma and single cells, were selectively captured by dispersed magnetic Fe3O4@TiO2 nanocomposite particles (40 μg). A suspension containing Fe3O4@TiO2 nanoparticles was loaded into a glass capillary (i.d. 0.75 mm) by capillary force. The supernatant solution was discarded, while the Fe3O4@TiO2 particles were retained inside the capillary by using an external magnetic field (ca. 1.3 T). The phospholipids on the surface of Fe3O4@TiO2 nanoparticles were directly analyzed using internal extractive electrospray ionization mass spectrometry (iEESI-MS) by pumping ≤1 μL of extraction solution of methanol containing 1.5% ammonia (w/w) through the capillary tube toward the ESI tip. A single sample analysis was accomplished within 4 min. Phospholipids in blood plasma samples from 59 patients with ovarian cancer and 43 healthy controls, and 28 patients with pancreatic cancer and 23 healthy controls were studied. Based on the orthogonal partial least squares discriminant analysis (OPLS-DA), the cancer patients were confidently discriminated from the healthy controls. Phospholipids in single human cells (MV4–11 and NB4) were determined, showing the sensitivity for single cell analysis. Therefore the results demonstrated that rapid cancer differentiation is achieved using this approach through the detection of trace phospholipids in microvolume blood and cell samples with high sensitivity, high specificity, low sample consumption, and high throughput. [ABSTRACT FROM AUTHOR]

Comparative studies of molecular alterations upon cancer between mice and humans are of great importance in order to determine the relevance of research involving mouse cancer models to the development of diagnostic and therapeutic approaches in clinical practice as well as for the mechanistic studies of pathology in humans. Herein, using molecular fingerprinting by internal extractive electrospray ionization mass spectrometry (iEESI-MS), we identified 50 differential signals in mouse liver tissue and 62 differential signals in human liver tissue that undergo significant intensity alterations (variable importance in the project (VIP) >1.0) upon liver cancer, out of which only 27 were common in both mouse and human tissues. Out of the 27 common differential signals, six types of phospholipids were also identified to undergo significant alterations in human serum upon liver cancer, including PC(34:2), PC(36:4), PC(38:6), PC(36:2), PC(38:4) and PC(42:9). Statistical analysis of the relative intensity distribution of these six identified phospholipids in serum allowed confident determination of liver cancer in humans (sensitivity 91.0%, specificity 88.0%, and accuracy 90.0%). Our results indicate that, despite the significant difference in the overall alterations of phospholipid profiles upon liver cancer between humans and mice, the six identified 'core' differential phospholipids of liver cancer found in the liver tissues of both humans and mice as well as in human serum show high potential as a minimal panel for the rapid targeted diagnosis of liver cancer with high accuracy, sensitivity and specificity using direct mass spectrometry (MS) analysis. [ABSTRACT FROM AUTHOR]

It is of sustainable interest to improve the sensitivity and selectivity of the ionization process, especially for direct analysis of complex samples without matrix separation. Herein, four ambient ionization methods including desorption atmospheric pressure chemical ionization (DAPCI), heat-assisted desorption atmospheric pressure chemical ionization (heat-assisted DAPCI),microwave plasma torch (MPT) and internal extractive electrospray ionization (iEESI) were employed for comparative analysis of the navel orange tissue samples by mass spectrometry. The volatile organic compounds (e.g. ethanol, vanillin, leaf alcohol and jasmine lactone) were successfully detected by non-heat-assisted DAPCI-MS, while semi-volatile organic compounds (e.g. 1-nonanol and ethyl nonanoate) together with low abundance of non-volatile organic compounds (e.g. sinensetin and nobiletin) were obtained by heat-assisted DAPCI-MS. Typical nonvolatile organic compounds [e.g. 5-(hydroxymethyl)furfural and glucosan] were sensitively detected with MPT-MS. Compounds of high polarity (e.g. amino acids, alkaloids and sugars) were easily profiled with iEESI-MS. Our data showed that more analytes could be detected when more energy was delivered for the desorption ionization purpose; however, heat-sensitive analytes would not be detected once the energy input exceeded the dissociation barriers of the analytes. For the later cases, soft ionizationmethods such as iEESIwere recommended to sensitively profile the bioanalytes of high polarity. Copyright © 2017 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Correction for 'Direct analysis of metabolites in the liver tissue of zebrafish exposed to fiproles by internal extractive electrospray ionization mass spectrometry' by Jun Liu et al., Analyst, 2021, 146, 4480–4486, https://doi.org/10.1039/D1AN00490E. [ABSTRACT FROM AUTHOR]

Polycyclic aromatic hydrocarbons (PAHs) are a group of ubiquitous environmental contaminants raising worldwide concerns due to their carcinogenic effects. In this study, 1-hydroxypyrene (1-OHP, the most widely used biomarker of internal dose of PAHs exposure) in undiluted human urine samples (10 mL) was selectively enriched by polypyrrole-coated Fe 3 O 4 magnetite nanocomposites (termed as Fe 3 O 4 @Ppy, 1 mg) and then directly eluted by the electrospraying solvent (acetone/benzene/acetic acid (v/v/v, 90/10/1); 100 uL) biased with −3.5 kV to produce the deprotonated 1-OHP anions for mass spectrometric analysis. The method established here significantly improved the current performance for detection of urinary 1-OHP, providing the speed for a single sample analysis within 4 min, the limits of detection (LOD) of 0.0001 μg L −1 , the linear response range of 0.001–5.000 μg L −1 (R 2 = 0.9994), recovery rates of 90.6–96.1%, and relative standard deviation (RSD, n = 6) values between 2.9% and 8.0%. Human samples including raw human urine collected from 10 healthy volunteers (5 smokers and 5 nonsmokers) and 7 lung cancer patients have been successfully analyzed, showing that magnetic solid-phase extraction (MSPE) coupled with internal extractive electrospray ionization mass spectrometry (iEESI-MS) is an alternative strategy for high throughput quantitative detection of urinary 1-OHP for health risk assessment of PAHs exposure. [ABSTRACT FROM AUTHOR]

Direct molecular analysis of tissue samples is a promising approach to increase the accuracy, speed and molecular specificity of cancer diagnosis. Herein, alterations of amino acids between human lung cancer tissues and matched adjacent normal tissues were profiled by internal extraction electrospray ionization mass spectrometry (iEESI-MS). The results indicated that the levels of 11 detected amino acids (including serine, proline, valine, threonine, asparagine, aspartic acid, methionine, histidine, phenylalanine, arginine and tyrosine) in the cancerous tissues were lower than that in the adjacent normal tissues. Based on the orthogonal partial least squares discriminant analysis (OPLS-DA) model, cancerous and adjacent normal tissues were clearly discriminated, and the amino acids that played the major role in the differentiation between cancerous and adjacent normal tissues were identified. Moreover, metabolic pathway analysis revealed alterations of differential amino acids in several metabolic pathways upon lung cancer. The current study extends the power of iEESI-MS as a promising tool for quantitative characterization of amino acids in tissues, and allows the study of alterations in amino acids metabolism associated with the development of lung cancer. [Display omitted] • Direct quantitative and qualitative analysis of amino acids in lung cancer tissues was achieved by iEESI-MS. • The levels of determined 11 amino acids in the cancerous tissues were lower than that in the adjacent normal tissues. • Alterations of differential amino acids in several metabolic pathways upon lung cancer were revealed. [ABSTRACT FROM AUTHOR]