Synthesis of histidine, serine and folic acid-functionalized and boron and iron-doped graphene quantum dot with excellent optical behavior and peroxidase-like activity for colorimetric and fluorescence detection of H2O2 in food.

Low fluorescence under visible light excitation and catalytic activity limit many applications of graphene quantum dots in optical detection, biosensing, catalysis and biomedical. The paper reports design and synthesis of histidine, serine and folic acid-functionalized and boron and iron-doped graphene quantum dot (Fe/B-GQD-HSF). The Fe/B-GQD-HSF shows excellent fluorescence behavior and peroxidase-like activity. Excitation of 330 nm ultraviolet light produces the strongest blue fluorescence and excitation of 480 nm visible light produces the strongest yellow fluorescence. The specific activity reaches 92.67 U g-1, which is higher than that of other graphene quantum dots. The Fe/B-GQD-HSF can catalyze oxidation of 3,3',5,5'-tetramethylbenzidine with H2O2 to form blue compound. Based on this, it was used for colorimetric and fluorescence detection of H2O2. The absorbance at 652 nm linearly increases with the increase of H2O2 concentration between 0.5 and 100 µM with detection limit of 0.43 µM. The fluorescence signal linearly decreases with the increase of H2O2 concentration between 0.05 and 100 µM with detection limit of 0.035 µM. The analytical method has been satisfactorily applied in detection of H2O2 in food. The study also paves one way for design and synthesis of functional graphene quantum dots with ideal fluorescence behavior and catalytic activity.

Cu,Ce-containing phosphotungstates as laccase-like nanozyme for colorimetric detection of Cr(VI) and Fe(â ¢).

Herein, a nanocomposite of Cu,Ce-containing phosphotungstates (Cu,Ce-PTs) with outstanding laccase-like activity was fabricated via a one-pot microwave-assisted hydrothermal method. Notably, it was discovered that both Fe3+ and Cr6+ could significantly enhance the electron transfer rates of Ce3+ and Ce4+, along with generous Cu2+ with high catalytic activity, thereby promoting the laccase-like activity of Cu,Ce-PTs. The proposed system can be used for the detection of Fe3+ and Cr6+ in a range of 0.667-333.33 µg/mL and 0.033-33.33 µg/mL with a low detection limit of 0.135 µg/mL and 0.0288 µg/mL, respectively. The proposed assay exhibits excellent reusability and selectivity and can be used in traditional Chinese medicine samples analysis.

In vitro toxicity assessment of bioavailable iron in coal varieties of Central India.

INTRODUCTION: Information on bioavailable Iron (BAI) content in respirable coal dust (RCD) is crucial to address occupational health and safety, especially in preventing coal workers' pneumoconiosis (CWP). MATERIALS AND METHODS: In the present study, we determined BAI concentrations in seventy-seven coal samples collected from ten coal mining regions of Central India. The cytotoxic potential of BAI-RCD was established invitro by using alveolar epithelial (A549) and macrophage (U937) cell lines. The oxidative/antioxidant status, inflammations, and genotoxicity attributed to BAI-RCD exposure were evaluated and correlated with CWP pathophysiology. RESULTS: The mean BAI concentrations in the coal samples (n = 77) range from (275 to 9065 mg kg-1) and showed wide variability. Both cell lines were exposed to low (275 mg kg-1), moderate (4650 mg kg-1), and high (9065 mg kg-1) BAI-RCD samples showed significant (p < 0.001) cytotoxicity in a dose-dependent manner (low < moderate < high) compared to the control. After BAI-RCD treatment, both cell lines showed a decrease in antioxidant stress measures (SOD, CAT, and GSH) and a significant (p < 0.001) increase in oxidative stress parameters (NADPH, MPO, LPO, and PC). Furthermore, these cell line models demonstrated a statistically significant (p < 0.001) dose-dependent increase in cytokines (TGF-ß1, IL-1ß, TNF-α, MCP-1, and IL-6 cytokines) and oxidative DNA damage marker (8-OH-dG). CONCLUSION: Results indicated that the central India coals (even at low BAI content) may be accountable for inflammatory responses and cytotoxicity. Hence, BAI can be important characteristic to establish safety standards for coal dust exposure before active mining.

Qualitative evaluation of trace elements in commercially packaged forms of tobacco using laser-induced breakdown spectroscopy.

Oral cancer is the most common malignancy in many developing countries, such as India, due to increased consumption of smokeless tobacco. The trace elemental components in commercially packaged forms of tobacco can play a significant role in the pathogenesis of oral cancer. To qualitatively assess the trace elements in various types of commercially packaged forms of tobacco using laser-induced breakdown spectroscopy (LIBS). Two popular varieties of 'Paan masala' that contained a mixture of slaked lime with areca nut, catechu, and other flavouring agents (tobacco was absent) and four types of packaged tobacco were obtained from 'Paan' shops. The contents in the packets were made into pellets using a hydraulic press and subjected to elemental analysis using LIBS. A ten-trial experiment was carried out on all six pellets. The National Institute of Standards and Technology (NIST) database was used to assess the emission lines. The elements obtained from commercially packaged tobacco and Paan masala were similar: calcium (Ca), iron (Fe), aluminium (Al), nickel (Ni), and chromium (Cr). Substances that cause DNA damage and carcinogenesis are inorganic elements such as nickel. Our study revealed that carcinogens such as nickel are present in the commercially packaged forms of tobacco and 'Paan masala' samples.

Bioaccessibility of carotenoids, tocochromanols, and iron from common bean (Phaseolus vulgaris L.) landraces.

Common beans (Phaseolus vulgaris L.) are among the most important legumes for human nutrition. The aim of the present study was to characterize the composition and in vitro bioaccessibility of tocochromanols, carotenoids, and iron from 14 different landraces and 2 commercial common bean varieties. Phytic acid, dietary fiber, and total (poly)phenolic content were determined as factors that can modify the bioaccessibility of the studied compounds. Two carotenoids were identified, namely lutein (4.6-315 ng/g) and zeaxanthin (12.2-363 ng/g), while two tocochromanols were identified, namely γ-tocopherol (2.62-18.01 µg/g), and δ-tocopherol (0.143-1.44 µg/g). The iron content in the studied samples was in the range of 58.7-144.2 µg/g. The contents of carotenoids, tocochromanols, and iron differed significantly among the studied samples but were within the ranges reported for commercial beans. After simulated gastrointestinal digestion, the average bioaccessibility of carotenoids was 30 %, for tocochromanols 50 %, and 17 % for iron. High variability in the bioaccessible content yielded by the bean varieties was observed. Dietary fiber, phytic acid and total (poly)phenol contents were negatively correlated with the bioaccessibility of carotenoids, while iron bioaccessibility was negatively correlated with the total (poly)phenol content. The principal component analysis indicated that the bioaccessibility of lutein was the main variable involved in class separations. The composition of the food matrix plays an important role in the bioaccessibility of carotenoids, tocochromanols and iron from cooked beans.

Spillover effects of structure-adjustment pollution reduction measures in China's iron and steel industry.

The iron and steel industry (ISI) is a significant source of sulfur dioxide and particulate matter pollution in China. Existing research on regional environmental regulation or ISI emission reduction strategies tends to overlook spillover effects and the enterprise perspective. During the heating season, production limitations in ISI are potential policy measures for achieving structural emission reductions in heavily polluted cities in China's Jing-Jin-Ji and surrounding regions. We adopt a bottom-up modeling approach, incorporating effective production time to describe enterprise behavior and establishing a quantitative trade model based on trade theory. By modeling three types of production restriction policies outlined in policy documents, we evaluate the emission reduction effects of structure-adjustment measures using the example of reduced effective production time for steel-producing enterprises in the air pollution transmission channel in the Beijing-Tianjin-Hebei area. The results indicate the following: (1) Reducing the effective production time of ISI enterprises can help decrease domestic production value and total factor productivity in pollution-intensive industries, including but not limited to ISI. It also leads to reduced emissions of various pollutants in the implementation regions. (2) Due to interprovincial trade and input-output linkages, structural reduction measures in certain regions have implications for almost all other provinces' industrial structures. Differences in initial industrial structures, factor endowments, and geographical locations contribute to varying directions and magnitudes of industrial structural changes. Pollution-intensive industries' share tends to increase higher in less developed regions. (3) Our estimated pollution reduction is smaller compared to the literature evaluating clean air policies in similar regions using top-down strategies. This discrepancy arises because we analyze a single policy tool rather than modeling industry-wide emission fluctuations from the top down. Additionally, our modeling approach allows us to examine dynamic changes in comparative advantages. The increase in production scale for certain industries in policy-affected regions partially offsets the decline in pollution emissions. These findings enhance our understanding of structure-adjustment reduction measures' role and highlight their potential advantages and limitations.

Impact of long-term irrigation practices on distribution and speciation of arsenic in agricultural soil.

To better understand the impact of long-term irrigation practices on arsenic (As) accumulation in agricultural soils, 100 soil samples from depths of 0-20 cm were collected from the Datong basin, where the As-contaminated groundwater has been used for irrigation for several decades. Soil samples were analyzed for major elements, trace elements, and As, Fe speciation. Results reveal As content ranging from 4.00 to 14.5 mg/kg, an average of 10.2 ± 2.05 mg/kg, consistent with surveys conducted in 1998 and 2007. Arsenic speciation ranked in descending order as follows: As associated with silicate minerals (AsSi, 29.70 ± 7.53 %) > amorphous Fe-minerals associated As (AsFeox1, 26.40 ± 3.27 %) > crystalline Fe-minerals associated As (AsFeox2, 24.02 ± 4.60 %) > strongly adsorbed As (AsSorb, 14.29 ± 2.81 %) > As combined with carbonates and Fe-carbonates (AsCar, 2.30 ± 0.44 %) > weakly adsorbed As (AsDiss, 2.59 ± 1.00 %). The anomalous negative correlation between As and Fe content reflects the primary influence of soil provenance. Evidence from major element compositions and rare earth element patterns indicates that total As and Fe contents in soils are controlled by parent materials, exhibiting distinct north-south differences (As: higher levels in the north, lower levels in the south; Fe: higher levels in the south, lower levels in the north). Evidence from the Chemical Index of Alteration (CIA) and As/Ti ratio suggests that chemical weathering has led to As enrichment in the central basin. Notably, relationships such as AsDiss/Ti, AsSorb/Ti with CIA and total Fe content indicate significant influences of irrigation practices on adsorbed As (both weakly and strongly adsorbed) contents, showing a pattern of higher levels in the central basin and lower levels in the Piedmont. However, total As content remained stable after long-term irrigation, potentially due to the re-release of accumulated As via geochemical pathways during non-irrigated periods. These findings demonstrate that the soil systems can naturally remediate exogenous As contamination induced by irrigation practices. Quantitative assessment of the balance between As enrichment and re-release in soil systems is crucial for preventing soil As contamination, highlighting strategies like water-saving techniques and fallow periods to manage As contamination in agricultural areas using As-contaminated groundwater for irrigation.

Integrated gold nanorods-based dual-signal platform for accurate total antioxidant capacity assessment in food samples.

Accurate assessment of Total Antioxidant Capacity (TAC) in food is crucial for evaluating nutritional quality and potential health benefits. This study aims to enhance the sensitivity and reliability of TAC detection through a dual-signal method, combining colorimetric and photothermal signals. Gold nanorods (AuNRs) were utilized to establish a dual-signal method duo to the colorimetric and photothermal properties. Fenton reaction can etch the AuNRs from the tips, as a result, a blue shift in the longitudinal LSPR absorption peak was obtained, leading to significant changes in color and photothermal effects, facilitating discrimination through both visual observation and thermometer measurements. In the presence of antioxidants, the Fenton reaction was suppressed or inhibited, protecting the AuNRs from etching. The colorimetric and photothermal signals were therefore positively correlated with TAC levels, enabling dual-signal detection of TAC. The linear range of AA was 4-100 µM in both colorimetry and photothermal modes, with detection limits of 1.60 µM and 1.38 µM, respectively. This dual-signal approach achieves low detection limits, enhancing precision and sensitivity. The method thus has the potential to act as a promising candidate for TAC detection in food samples, contributing to improved food quality and safety assessment.

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.

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.

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.

Trimetallic FeCoNi Metal-Organic Framework with Enhanced Peroxidase-like Activity for the Construction of a Colorimetric Sensor for Rapid Detection of Thiophenol in Water Samples.

In recent years, nanozymes have attracted particular interest and attention as catalysts because of their high catalytic efficiency and stability compared with natural enzymes, whereas how to use simple methods to further improve the catalytic activity of nanozymes is still challenging. In this work, we report a trimetallic metal-organic framework (MOF) based on Fe, Co and Ni, which was prepared by replacing partial original Fe nodes of the Fe-MOF with Co and Ni nodes. The obtained FeCoNi-MOF shows both oxidase-like activity and peroxidase-like activity. FeCoNi-MOF can not only oxidize the chromogenic substrate 3,3,5,5-tetramethylbenzidine (TMB) to its blue oxidation product oxTMB directly, but also catalyze the activation of H2O2 to oxidize the TMB. Compared with corresponding monometallic/bimetallic MOFs, the FeCoNi-MOF with equimolar metals hereby prepared exhibited higher peroxidase-like activity, faster colorimetric reaction speed (1.26-2.57 folds), shorter reaction time (20 min) and stronger affinity with TMB (2.50-5.89 folds) and H2O2 (1.73-3.94 folds), owing to the splendid synergistic electron transfer effect between Fe, Co and Ni. Considering its outstanding advantages, a promising FeCoNi-MOF-based sensing platform has been designated for the colorimetric detection of the biomarker H2O2 and environmental pollutant TP, and lower limits of detection (LODs) (1.75 µM for H2O2 and 0.045 µM for TP) and wider linear ranges (6-800 µM for H2O2 and 0.5-80 µM for TP) were obtained. In addition, the newly constructed colorimetric platform for TP has been applied successfully for the determination of TP in real water samples with average recoveries ranging from 94.6% to 112.1%. Finally, the colorimetric sensing platform based on FeCoNi-MOF is converted to a cost-effective paper strip sensor, which renders the detection of TP more rapid and convenient.

Water-Stable Ln-MOF as a multi-emitting luminescent sensor for the detection of metal ions and pharmaceuticals.

The development of innovative multi-emission sensors for the rapid and accurate detection of contaminants is both vital and challenging. In this study, utilizing two rigid ligands (H3ICA and H4BTEC), a series of water-stable bimetallic organic frameworks (EuTb-MOFs) were synthesized. Luminescent investigations have revealed that EuTb-MOF-1 exhibits prominent multiple emission peaks, attributed to the distinctive fluorescence characteristics of Eu(III) and Tb(III) ions. Therefore, EuTb-MOF-1 efficiently recognized various metal ions and pharmaceutical compounds through 2D decoded maps. Fe3+ and Pb2+ exhibited significant quenching effects on the luminescence of EuTb-MOF-1, which were attributed to the internal filtering effect and the interaction between Lewis basic sites within EuTb-MOF-1 and Pb2+ ions, respectively. Furthermore, EuTb-MOF-1 demonstrated high sensitivity to sulfonamide antibiotics, with detection limits of 0.037 µM for SMZ and 0.041 µM for SDZ, respectively. In addition, EuTb-MOF-1 was immobilized to prepare MOF-based test strips, enabling direct visual detection of sulfonamides as a portable sensor. With excellent water stability, multi-responsive recognition capabilities, and high sensitivity to specific analytes, EuTb-MOF-1 is a promising candidate for environmental contaminant detection in aquatic systems.

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.

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.

Iron-binding biomolecules in the soluble hepatic fraction of the northern pike (Esox lucius): two-dimensional chromatographic separation with mass spectrometry detection.

Iron plays vital roles in important biological processes in fish, but can be toxic in high concentrations. The information on metalloproteins that participate in maintenance of Fe homeostasis in an esocid fish, the northern pike, as an important freshwater bioindicator species, are rather scarce. The aim of this study was to identify main cytosolic constituents that sequester Fe in the northern pike liver. The method applied consisted of two-dimensional HPLC separation of Fe-binding biomolecules, based on anion-exchange followed by size-exclusion fractionation. Apparent molecular masses of two main Fe-metalloproteins isolated by this procedure were ~360 kDa and ~50 kDa, with the former having more acidic pI, and indicated presence of ferritin and hemoglobin, respectively. MALDI-TOF-MS provided confirmation of ferritin subunit with a m/z peak at 20.65 kDa, and hemoglobin with spectra containing main m/z peak at 16.1 kDa, and smaller peaks at 32.1, 48.2, and 7.95 kDa (single-charged Hb-monomer, dimer, and trimer, and double-charged monomer, respectively). LC-MS/MS with subsequent MASCOT database search confirmed the presence of Hb-ß subunits and pointed to close relation between esocid and salmonid fishes. Further efforts should be directed towards optimization of the conditions for metalloprotein analysis by mass spectrometry, to extend the knowledge on intracellular metal-handling mechanisms.

Carbon-based materials from waste PVC/iron chips dechlorination as peroxidase mimics for total antioxidant capacity biosensing.

The monitoring of antioxidant capacity is very important to evaluate the quality of antioxidant foods or drugs for market regulation. Herein, dechlorination treatment of waste PVC/scrap irons were conducted in subcritical water to obtain carbon-based Fe composites (CM-Fe-dPVC) with peroxidase-like activity. The electron bonding of C 2p and Fe 3d orbital led to strong electron migration ability. CM-Fe-dPVC exhibited excellent activity of simulated peroxidase. Vitamin C (VC) and CM-Fe-dPVC had competitive behaviors on •OH generation in TMB oxidation reaction. A portable paper based colorimetric test kit was developed for monitoring total antioxidant capacity of beverages and pharmaceuticals on the market (with the detection limit of 0.1 µM for Vc). The results of life cycle assessment (LCA) revealed that the proposed strategy had low global warming potential. This research could provide important reference for high value recycling of organic solid wastes.

Iron-coated Komodo dragon teeth and the complex dental enamel of carnivorous reptiles.

Komodo dragons (Varanus komodoensis) are the largest extant predatory lizards and their ziphodont (serrated, curved and blade-shaped) teeth make them valuable analogues for studying tooth structure, function and comparing with extinct ziphodont taxa, such as theropod dinosaurs. Like other ziphodont reptiles, V. komodoensis teeth possess only a thin coating of enamel that is nevertheless able to cope with the demands of their puncture-pull feeding. Using advanced chemical and structural imaging, we reveal that V. komodoensis teeth possess a unique adaptation for maintaining their cutting edges: orange, iron-enriched coatings on their tooth serrations and tips. Comparisons with other extant varanids and crocodylians revealed that iron sequestration is probably widespread in reptile enamels but it is most striking in V. komodoensis and closely related ziphodont species, suggesting a crucial role in supporting serrated teeth. Unfortunately, fossilization confounds our ability to consistently detect similar iron coatings in fossil teeth, including those of ziphodont dinosaurs. However, unlike V. komodoensis, some theropods possessed specialized enamel along their tooth serrations, resembling the wavy enamel found in herbivorous hadrosaurid dinosaurs. These discoveries illustrate unexpected and disparate specializations for maintaining ziphodont teeth in predatory reptiles.

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.