Native metabolomics for mass spectrometry-based siderophore discovery.

Microorganisms, plants, and animals alike have specialized acquisition pathways for obtaining metals, with microorganisms and plants biosynthesizing and secreting small molecule natural products called siderophores and metallophores with high affinities and specificities for iron or other non-iron metals, respectively. This chapter details a novel approach to discovering metal-binding molecules, including siderophores and metallophores, from complex samples ranging from microbial supernatants to biological tissue to environmental samples. This approach, called Native Metabolomics, is a mass spectrometry method in which pH adjustment and metal infusion post-liquid chromatography are interfaced with ion identity molecular networking (IIMN). This rule-based data analysis workflow that enables the identification of metal-binding species based on defined mass (m/z) offsets with the same chromatographic profiles and retention times. Ion identity molecular networking connects compounds that are structurally similar by their fragmentation pattern and species that are ion adducts of the same compound by chromatographic shape correlations. This approach has previously revealed new insights into metal binding metabolites, including that yersiniabactin can act as a biological zincophore (in addition to its known role as a siderophore), that the recently elucidated lepotchelin natural products are cyanobacterial metallophores, and that antioxidants in traditional medicine bind iron. Native metabolomics can be conducted on any liquid chromatography-mass spectrometry system to explore the binding of any metal or multiple metals simultaneously, underscoring the potential for this method to become an essential strategy for elucidating biological metal-binding molecules.

[Mineral content in freshwater fish in Shaanxi Province in 2021].

OBJECTIVE: To understand the mineral content of freshwater fish produced in Shaanxi Province and evaluate its related nutritional value. METHODS: According to the 2021 Shaanxi Provincial nutrition monitoring plan, the 9 mineral contents of 13 varieties of freshwater fish, produced in Shaanxi province, were determined by inductively coupled plasma atomic emission spectrometry. The nutritional evaluation of mineral elements was carried out by using the index of nutritional quality(INQ) method. Simultaneously, the correlation between 9 minerals and energy was analyzed by SPSS software. RESULTS: Among the 13 fish species, the contents of P and K were highest, with content ranges of 169-255 and 159-373 mg/100 g, respectively, followed by sodium, calcium, magnesium, iron, zinc. The contents of copper and manganese were lowest. The nutritional evaluation showed that the INQ values of P, K and Mg were than 1, the INQ value of P was highest, which was 4.57-8.72. Some fish have INQ values greater than 1 for calcium, iron, copper and zinc. The correlation between the nine minerals was not strong, as a whole. Only some elements have a correlation coefficient greater than 0.6, indicating that there was a synergistic accumulation effect or antagonistic effect in the fish body. CONCLUSION: The dominant mineral elements in different species of fish were different. However, most fish species can be used as high-quality food sources of phosphorus, potassium, magnesium, copper and zinc.

Multicolor nitrogen-doped carbon quantum dots and its application in the detection of Fe3+ ion.

In this paper, nitrogen-doped carbon quantum dots (N-CQDs) are synthesized by the hydrothermal method. N-CQDs exhibit strong fluorescence, and N-CQDs are well dispersed in water as well as in various organic solvents. N-CQDs emit multi-color fluorescence from blue to red, with wavelengths in the range of 450-650 nm without the need for purification. Furthermore, the fluorescence emission of N-CQDs was selectively quenched after adding Fe3+ ions. N-CQDs were used as a nanoprobe for the detection of Fe3+ ions, showing a good linear correlation between the fluorescence emission and the concentration of Fe3+ in the Fe3+ concentration range from 0 to 100 µM. The limit of detection (LOD) was 55.7 µM for Fe3+ in water and 40.2 µM in fetal bovine serum (FBS) samples. The study shows that the synthesized N-CQDs have low cost and great potential for application in biological analysis.

Development of a NIR Iridium(III) Complex-Based Probe for the Selective Detection of Iron(II) Ions.

As a commonly used metal ion, iron(II) (Fe2+) ions pose a potential threat to ecosystems and human health. Therefore, it is particularly important to develop analytical techniques for the rapid and accurate detection of Fe2+ ions. However, the development of near-infrared (NIR) luminescence probes with good photostability for Fe2+ ions remain challenging. In this work, we report a novel iridium(III) complex-based luminescence probe for the sensitive and rapid detection of Fe2+ ions in a solution based on an Fe2+-mediated reduction reaction. This probe is capable of sensitively detecting Fe2+ ions with a limit of detection (LOD) of 0.26 µM. Furthermore, this probe shows high photostability, and its luminescence remains stable under 365 nm irradiation over a time period of 30 min. To our knowledge, this is first iridium(III) complex-based NIR probe for the detection of Fe2+ ions. We believe that this work provides a new method for the detection of Fe2+ ions and has great potential for future applications in water quality testing and human monitoring.

Global analysis of spatio-temporal variation in mineral nutritional quality of pepper (Capsicum spp.) fruit and its regulatory variables: A meta-analysis.

Pepper (Capsicum spp.) is an important fruit vegetable worldwide, and it is a rich dietary source of minerals for human being. Yet, the spatio-temporal distribution of pepper fruit mineral composition and the factors influencing such variations at global scale remain unknown. A global meta-analysis of 140 publications providing 649, 562, 690, 811 datapoints was conducted to quantify and evaluate the nutritional quality, comprising potassium (K), magnesium (Mg), iron (Fe) and zinc (Zn), of pepper fruits and its influencing variables. The analysis showed that the global average of K, Mg, Fe and Zn content in pepper fruits was 20-25 g kg-1, 1-1.5 g kg-1, 80-100 mg kg-1, and 20-40 mg kg-1, respectively. There had been a downward trend in pepper fruit nutritional quality over the last decade, especially for Fe and Zn. And, the concentration of all these four nutrients were at lower levels in less developed regions, especially in Africa. Our results showed that the vegetable "green pepper" contains more K, Mg, Fe and Zn than the "hot pepper" used as spice. The concentration of K, Mg, Fe and Zn were increased with fruit yield but that of Fe and Zn were decreased with increase in single fruit weight. Nutritional quality was optimal at mean annual temperature of 10 ℃ - 20 ℃, and was adversely affected when mean annual precipitation was < 500 mm. Pepper fruits produced at pH 6.5-7.5 had higher fruit K concentration while acidic soils (pH<6.5) favored higher Fe and Zn concentrations. The higher soil organic matter (SOM) generally improved the nutritional quality of the pepper. Our results suggest that systematic selection of superior varieties and soil amelioration (adjusting pH and SOM) of the soil-crop system are needed to achieve higher nutritional quality of pepper fruit.

Measurement of iron absorption and iron gains from birth to 6 months in breastfed and formula-fed infants using iron isotope dilution.

Little is known about iron kinetics in early infancy. We administered stable iron isotopes to pregnant women and used maternal-fetal iron transfer to enrich newborn body iron. Dilution of enriched body iron by dietary iron with natural isotopic composition was used to assess iron kinetics from birth to 6 months. In breastfed (BF, n = 8), formula-fed (FF, n = 7), or mixed feeding (MF, n = 8) infants, median (interquartile range) iron intake was 0.27, 11.19 (10.46-15.55), and 4.13 (2.33-6.95) mg/day; iron absorbed was 0.128 (0.095-0.180), 0.457 (0.374-0.617), and 0.391 (0.283-0.473) mg/day (BF versus FF, P < 0.01); and total iron gains were 0.027 (-0.002-0.055), 0.349 (0.260-0.498), and 0.276 (0.175-0.368) mg/day (BF versus FF, P < 0.001; BF versus MF, P < 0.05). Isotope dilution can quantify long-term iron absorption and describe the trajectory of iron depletion during early infancy.

Based on Fe and Ni prepared organic colloidal materials as efficient oxide nanozymes for chemiluminescence detection of GSH and Hg(II) ions.

Metal-organic gels (MOGs) are a type of metal-organic colloid material with a large specific surface area, loose porous structure, and open metal active sites. In this work, FeNi-MOGs were synthesized by the simple one-step static method, using Fe(III) and Ni(II) as the central metal ions and terephthalic acid as the organic ligand. The prepared FeNi-MOGs could effectively catalyze the chemiluminescence of luminol without the involvement of H2O2, which exhibited good catalytic activity. Then, the multifunctional detected platform was constructed for the detection of GSH and Hg2+, based on the antioxidant capacity of GSH, and the strong affinity between mercury ion (Hg2+) and GSH which inactivated the antioxidant capacity of GSH. The experimental limits of detection (LOD) for GSH and Hg2+ were 76 nM and 210 nM, and the detection ranges were 2-100 µM and 8-4000 µM, respectively. The as-proposed sensor had good performance in both detection limit and detection range of GSH and Hg2+, which fully met the needs of daily life. Surprisingly, the sensor had low detection limits and an extremely wide detection range for Hg2+, spanning five orders of magnitude. Furthermore, the detection of mercury ions in actual lake water and GSH in human serum showed good results, with recovery rates ranging from 90.10 % to 105.37 %, which proved that the method was accurate and reliable. The as-proposed sensor had great potential as the platform for GSH and Hg2+ detection applications.

A novel "ON-OFF-ON" colorimetric and fluorescence dual-signal sensing APAP based on TSPP-Fe3.

Acetaminophen, also known as paracetamol (APAP), is a commonly used over-the-counter medication that is often used to treat headaches, toothaches, joint pain, muscle pain, and to lower body temperature. However, overdose can lead to liver damage, gastrointestinal distress, kidney damage, and cardiovascular disease. Therefore, it is very important to establish a method to quickly detect APAP. A novel "ON-OFF-ON" colorimetric and fluorescence dual-signal sensing system was constructed for the quantitative detection of APAP based on 5,10,15,20-tetrakis(4-sulphonatophenyl) porphyrin (TSPP) dual-signal probe. The absorbance and fluorescence intensity of TSPP respectively were quenched when Fe3+ was introduced into TSPP solution. At this point, the color of the corresponding solution changed from red to green. The absorbance and fluorescence intensity of TSPP respectively were restored when APAP was added to the TSPP-Fe3+ system. At this time, the color of the solution changed from green to colorless. Therefore, an "ON-OFF-ON" dual-signal sensing study of APAP were constructed using TSPP as the colorimetric and fluorescent probe. The proposed colorimetric sensing system had a wide linear range in the 13.12 mM âˆ¼ 23.20 mM with 0.11 mM of limit of detection (LOD, S/N = 3). And the proposed fluorescence sensing system had a wide linear range in the 3.45 mM âˆ¼ 12.50 mM and 41.67 mM âˆ¼ 65.22 mM with 0.83 mM of limit of detection (LOD, S/N = 3). The dual-signal sensing system were applied to the APAP detection of real samples.

Subzero project: comparing trace element profiles of enriched mitochondria fractions from frozen and fresh liver tissue.

From organs to subcellular organelles, trace element (TE) homeostasis is fundamental for many physiological processes. While often overlooked in early stages, manifested TE disbalance can have severe health consequences, particularly in the context of aging or pathological conditions. Monitoring TE concentrations at the mitochondrial level could identify organelle-specific imbalances, contributing to targeted diagnostics and a healthier aging process. However, mitochondria isolation from frozen tissue is challenging, as it poses the risk of TE losses from the organelles due to cryodamage, but would significantly ease routine laboratory work. To address this, a novel method to isolate an enriched mitochondria fraction (EMF) from frozen tissue was adapted from already established protocols. Validation of manganese (Mn), iron (Fe), and copper (Cu) quantification via inductively coupled plasma tandem mass spectrometry (ICP-MS/MS) showed sufficiently low quantification limits for EMF TE analysis. Successful mitochondrial enrichment from frozen liver samples was confirmed via immunoblots and transmission electron microscopy (TEM) revealed sufficient structural integrity of the EMFs. No significant differences in EMF TEs between frozen and fresh tissue were evident for Mn and Cu and only slight decreases in EMF Fe. Consequently, EMF TEs were highly comparable for isolates from both tissue states. In application, this method effectively detected dietary differences in EMF Fe of a murine feeding study and identified the disease status in a Wilson disease rat model based on drastically increased EMF Cu. In summary, the present method is suitable for future applications, facilitating sample storage and high-throughput analyses of mitochondrial TEs.

Bioaccessibility of iron in developed pectin iron complex using Citrus limon Burm F. peels subjected to in-vitro gastro-pancreatic digestion.

Pectin from the citrus peel waste has novel applications in food and biomedical industries. The present work focused on addressing iron deficiency, which is a global health concern, by developing a functional ingredient using pectin extracted from Assam lemon (Citrus limon Burm. F) and supplementing iron via the pectin­iron complex (PIC). Extracted pectin was incubated with iron chloride hexahydrate (0.90-1.80 mM) for 180 h to optimize the complexation conditions, with the optimal concentration being 1.36 mM. The iron bioavailability and its absorption in the PIC was assessed using in-vitro simulation digestion and Caco-2 cell monolayers. The bioaccessible form of iron in the developed PIC during the intestinal phase was 5.34 ± 0.16%, which was negligible in pectin. The absorption of bioaccessible iron in the PIC was found to be 2.93 ± 0.03%. The results demonstrated that PIC could reduce iron deficiency and increase fibre intake, leading to several health benefits.

Kinetics of chemical and color changes in wheat and water during atmospheric cooking as affected by the acidity, hardness, and iron content of water.

Color changes in wheat and cooking water, which affect the quality of bulgur and wastewater, are important. Understanding the impacts of cooking water acidity, hardness, and iron content is significant for producing bright-yellow colored bulgur and determining the possible negative effects of cooking water on the environment. Thereby, the gelatinization degree and color (L*, a*, b*, and yellowness index) of wheat cooked with waters at different pH (3, 5, 7, 9, and 11), hardness (soft, hard, and very hard), and iron content (0, 1, and 2 mg/L) were determined every 10 min of cooking. pH, Brix, conductivity, hardness, turbidity, and color of cooking waters were also determined and kinetically modeled. After cooking, it was revealed that cooking with water at pH 3 favored the color of cooked wheat, whereas pH 11 caused darkening. Nevertheless, as the wastewater pH of cooking waters with pH 3 and 11 may be harmful to the environment, it is recommended to use water in the range of pH 5-9 for bulgur production. Cooking with very hard water is also not recommended as it causes some adverse effects such as diminishing the gelatinization rate in wheat, increasing the cooking time, and negatively affecting the color.

Au nanoparticles decorated graphitic carbon nitride nanosheets as a sensitive and selective fluorescence probe for Fe3+ and dichromate ions in aqueous medium.

Graphitic carbon nitride mutated with metal nanoparticles has captivated great interest as an effective fluorescent sensor for the detection of harmful ions present in water. In the present work, bulk-gCN was synthesized using melamine as precursor, and further Au-gCN nanocomposite were fabricated via in-situ direct reduction deposition method. The structural, morphological, compositional, stability and optical properties of bulk gCN and Au-gCN nanocomposite were examined using various scattering and spectroscopic techniques such as HRTEM, XPS, XRD and SEM. The synthesized bulk gCN straggles during selectivity studies with different cations and anions because of its uneven surface morphology, however in Au-gCN gold nanoparticles are uniformly distributed on the gCN sheets which results in its enhanced selectivity over bulk gCN. This leads to the fabrication of an optical sensor for Fe3+ and Cr2O72- ions with limit of detection of 4.62 and 2.77 µM, respectively. The sensing of Fe3+ ions corresponds to the photoinduced electron transfer (PET) mechanism, while the detection of chromate species is associated with an inner filter effect (IFE). The practical applicability of the sensor was also evaluated for different environmental water samples. The high stability, sensitivity, and specificity of Au-gCN nanocomposite make it a potential fluorescent probe for Fe3+ and Cr2O72- ions in water samples.

Dye-sensitized lanthanide-doped upconversion nanoprobe for enhanced sensitive detection of Fe3+ in human serum and tap water.

Iron ion (Fe3+) detection is crucial for human health since it plays a crucial role in many physiological activities. In this work, a novel Schiff-base functionalized cyanine derivative (CyPy) was synthesized, which was successfully assembled on the surface of upconversion nanoparticles (UCNPs) through an amphiphilic polymer encapsulation method. In the as-designed nanoprobe, CyPy, a recognizer of Fe3+, is served as energy donor and ß-NaYF4:Yb,Er upconversion nanoparticles are adopted as energy acceptor. As a result, a 93-fold enhancement of upconversion luminescence is achieved. The efficient energy transfer from CyPy to ß-NaYF4:Yb,Er endows the nanoprobe a high sensitivity for Fe3+ in water with a low detection limit of 0.21 µM. Moreover, the nanoprobe has been successfully applied for Fe3+ determination in human serum and tap water samples with recovery ranges of 95 %-105 % and 97 %-106 %, respectively. Moreover, their relative standard deviations are all below 3.72 %. This work provides a sensitive and efficient methodology for Fe3+ detection in clinical and environmental testing.

Highly sensitive determination of trace arsenic(III) onto carbon paste electrode modified with graphitic carbon nitride decorated Fe-MOF.

An effective electrochemical sensor was developed to detect and determine of the As(III) by modifying the carbon paste electrode (CPE) with graphitic carbon nitride decorated with iron-based metal-organic frameworks (Fe-MOF/g-C3N5). The differential pulse anodic stripping voltammetry (DPASV) method was used to analyze As(III) ions in a phosphate buffer solution (0.10 M, pH = 5). Fe-MOF/g-C3N5/CPE showed high sensitivity (4.24 µA µg-1 L), satisfactory linear range (0.50 µg L-1-5.00 µg L-1 and 5.00 µg L-1-30.00 µg L-1), and low detection limit (LOD, 0.013 µg L-1). The prepared sensor was showed an excellent repeatability and selectivity, and successfully used for determination of the As(III) ion in ambient waters and apple juice samples.

A novel ratiometric electrochemical sensing platform combined with molecularly imprinted polymer and Fe-MOF-NH2/CNTs-NH2/MXene composite for efficient detection of ofloxacin.

BACKGROUND: Ofloxacin (OFL) is often abused in medicine and animal husbandry, which poses a great threat to human health and ecological environment. Therefore, it is necessary to establish efficient method to detect OFL. Electrochemical sensor has attracted widespread attention due to the advantages of low cost and fast response. However, most electrochemical sensors usually use one response signal to detect the target, which makes it sensitive to the variable background noise in the complex environment, resulting in low robustness and selectivity. The ratio detection mode and employing molecularly imprinted polymer (MIP) are two strategies to solve these problems. RESULTS: A novel molecular imprinting polymer-ratiometric electrochemical sensor (MIP-RECS) based on Fe-MOF-NH2/CNTs-NH2/MXene composite was prepared for the rapid and sensitive detection of OFL. The positively charged Fe-MOF-NH2 and CNTs-NH2 as interlayer spacers were introduced into the negatively charged MXene through a simple electrostatic self-assembly technique, which effectively prevented the agglomeration of MXene and increased the electrocatalytic activity. A glass carbon electrode was modified by the composite and a MIP film was electropolymerized on it using o-phenylenediamine and ß-cyclodextrin as bifunctional monomers and OFL as template. Then a MIP-RECS was designed by adding dopamine (DA) into the electrolyte solution as internal reference, and OFL was quantified by the response current ratio of OFL to DA. The current ratio and the concentration of OFL displayed a satisfying linear relationship in the range of 0.1 µM-100 µM, with a limit of detection (LOD) of 13.2 nM. SIGNIFICANCE: Combining molecular imprinting strategy and ratio strategy, the MIP-RECS has impressive selectivity compared with the non-imprinted polymer-RECS, and has better repeatability and reproducibility than non-ratiometric sensor. The MIP-RECS has high sensitivity and accuracy, which was applied for the detection of OFL in four different brands of milk and was verified by HPLC method with satisfactory results.

Abnormality in Peripheral and Brain Iron Contents and the Relationship with Grey Matter Volumes in Major Depressive Disorder.

Major depressive disorder (MDD) is a prevalent mental illness globally, yet its etiology remains largely elusive. Recent interest in the scientific community has focused on the correlation between the disruption of iron homeostasis and MDD. Prior studies have revealed anomalous levels of iron in both peripheral blood and the brain of MDD patients; however, these findings are not consistent. This study involved 95 MDD patients aged 18-35 and 66 sex- and age-matched healthy controls (HCs) who underwent 3D-T1 and quantitative susceptibility mapping (QSM) sequence scans to assess grey matter volume (GMV) and brain iron concentration, respectively. Plasma ferritin (pF) levels were measured in a subset of 49 MDD individuals and 41 HCs using the Enzyme-linked immunosorbent assay (ELISA), whose blood data were simultaneously collected. We hypothesize that morphological brain changes in MDD patients are related to abnormal regulation of iron levels in the brain and periphery. Multimodal canonical correlation analysis plus joint independent component analysis (MCCA+jICA) algorithm was mainly used to investigate the covariation patterns between the brain iron concentration and GMV. The results of "MCCA+jICA" showed that the QSM values in bilateral globus pallidus and caudate nucleus of MDD patients were lower than HCs. While in the bilateral thalamus and putamen, the QSM values in MDD patients were higher than in HCs. The GMV values of these brain regions showed a significant positive correlation with QSM. The GMV values of bilateral putamen were found to be increased in MDD patients compared with HCs. A small portion of the thalamus showed reduced GMV values in MDD patients compared to HCs. Furthermore, the region of interest (ROI)-based comparison results in the basal ganglia structures align with the outcomes obtained from the "MCCA+jICA" analysis. The ELISA results indicated that the levels of pF in MDD patients were higher than those in HCs. Correlation analysis revealed that the increase in pF was positively correlated with the iron content in the left thalamus. Finally, the covariation patterns obtained from "MCCA+jICA" analysis as classification features effectively differentiated MDD patients from HCs in the support vector machine (SVM) model. Our findings indicate that elevated peripheral ferritin in MDD patients may disrupt the normal metabolism of iron in the brain, leading to abnormal changes in brain iron levels and GMV.

Prevalence, variety, and iron and zinc content of commercial infant and toddler foods sold in the United States that contain meat.

Iron and zinc are important nutrients during infancy, particularly for infants exclusively fed human milk at the beginning of complementary feeding (CF) from 6-12 months. The 1st Foods Study examined the ingredients and nutrient contents of commercially-available infant and toddler foods (ITFs) that were sold in the US and contained meat. Company websites (n = 22) were used to create a database of commercial ITFs (n = 165) available for purchase in the US and contained at least one meat (e.g., beef, chicken, pork). Single ingredient and ready-to-serve meals (for ages ≤ 9 months) and ready-to-serve meals (for ages 10+ months) were categorized as infant and toddler products, respectively. For each product, the ingredient list, intended age/stage, serving size (g), energy (kcal), protein (g), iron (mg), and zinc (mg) per serving were recorded from product labels. Nutrient amount/100 g was calculated for each product and medians and inter-quartile ranges were calculated and compared (1) by intended age/stage of the product and (2) according to meat type. In general, toddler products contained more iron than infant products. Within infant products (n = 65), more iron was found in products containing beef relative to products with other meats, which were similar in iron content. Within toddler products (n = 38), more iron was found in products containing seafood, followed by beef, turkey, and pork. Slightly less iron was found in products with chicken. Zinc content was infrequently reported (n = 17 total products). Because many of the products assessed contained low amounts of iron and zinc, meeting the current infant and toddler requirements for iron and zinc during the CF period may be challenging if commercial ITFs containing meat are the primary source of these nutrients.

A selective bis-thiophene chalcone-based spectrofluorimetric sensor for Fe3.

A highly selective bis thiophene-based chalcone as a chemosensor for detecting Fe3+ metal ions in DMF: H2O (9:1). This sensor was selective toward ferric ions over other metal ions with a detection limit in micromolar range.

ICP-MS Analysis of Iron from Biological Samples.

Elemental analysis can provide trace concentrations of iron and other transition elements at nanomolar (µg/L) concentrations in whole bacterial and mammalian cells, subcellular compartments, biological fluids, and tissues. The best method of analysis is by far Inductively Coupled Plasma Mass Spectrometry (ICP-MS). I describe here a very general method for the sample preparation, instrument settings, method development, and analysis. The method can be extended to up to 20 common elements in biological samples.

Sample Preparation for X-Ray Fluorescence Microscopy of Iron Distribution in Biological Specimen.

Characterizing the two- and three-dimensional distribution of trace metals in biological specimens is key to better understand their role in biological processes. Iron (Fe) is of particular interest in these trace metals due to its widespread role in maintaining cellular health and preventing disease. X-ray fluorescence microscopy (XFM) is emerging as the method of choice for investigators to interrogate the cellular and subcellular distribution of Fe. XFM utilizes the intrinsic X-ray fluorescence properties of each element to produce quantitative 2D and 3D distributions of trace metals within a sample. Herein, methods for sample preparation of cells and tissue for the determination of Fe distribution by XFM are described.