Chromatography Research Articles

Development of a gradient method for sulfamethoxazole, trimethoprim, isoniazid, and pyridoxine hydrochloride in rabbit plasma through QbD-driven investigation

The current study developed a method for quantifying four drugs—Sulfamethoxazole, Trimethoprim, Isoniazid, and Pyridoxine—in rabbit plasma. The method uses gradient liquid chromatography based on analytical quality by design. To achieve separation, a Eclip Plus C18 (250 mm × 5 mm, 4.6 µm) column with L1 packing was used, and analytes were detected at 254 nm at ambient temperature. The optimized mobile phase consisted of 50 mM potassium dihydrogen phosphate buffer (pH 6.5) and Methanol. The concentration of Methanol was 3% (0–5 min), 15% (5–15 min), 55% (15–27 min), and 3% Methanol until the end of the 30-min runtime, and the flow rate was set at 0.95 mL/min. Control Noise Experimentation was used to screen studies, revealing that flow rate, pH, and Methanol concentration significantly affected the analytical attributes. The study identified critical attributes (resolution and asymmetric factor) and developed a quality target method profile. A central composition design was used to optimize the essential parameters. The method developed for the drugs showed peaks at retention times of 6.990 min for Isoniazid, 7.880 min for Pyridoxine, 15.530 min for Sulfamethoxazole, and 26.890 min for Trimethoprim, respectively. The method was validated with linearity in the range of 10–640 ng ml−1, with R2 of 0.9993, 0.9987, 0.9993, and 0.9992 for Sulfamethoxazole, Trimethoprim, Isoniazid, and Pyridoxine, respectively.

Macrophage Membrane-Coated Nanoparticles for the Delivery of Natamycin Exhibit Increased Antifungal and Anti-Inflammatory Activities in Fungal Keratitis.

This study aims to explore the efficacy and safety of macrophage membrane-coated nanoparticles for the delivery of natamycin (NAT) in the therapy of fungal keratitis (FK). Macrophage membranes were isolated and identified by immunofluorescence staining (IFS). NAT was encapsulated into poly(lactic-co-glycolic acid) (PLGA). Fungal stimulated macrophage membranes (M1) or unstimulated membranes (M) were separately mixed and sonicated with PLGA nanoparticles. The biocompatible nanoparticles (PLGA-NAT, PLGA-NAT@M, and PLGA-NAT@M1) were characterized with zeta-sizer analysis, transmission electron microscopy (TEM), and Western blot. Drug encapsulation and loading efficiency and the release of NAT in the nanoparticles were detected by ultraviolet spectrophotometry. The cytotoxicity, ocular surface toxicity and irritability, and systemic safety of nanoparticles with different concentrations were assessed. In vitro, we examined the antifungal properties of the nanoparticles. The eye surface retention time, drug release, and curative effects on FK were evaluated in vitro and in vivo. IFS results showed the separation of the macrophage membrane and nucleus. The prepared nanoparticles had a typical "core-shell" structure and uniform nanometer size, and the membrane proteins were retained on the membrane allowing to exert functional effects of macrophage. The loading efficiencies of PLGA-NAT@M and PLGA-NAT@M1 were 7.6 and 6.7%, respectively. The encapsulation efficiencies of PLGA-NAT@M and PLGA-NAT@M1 were 51.2 and 41.5%, respectively. PLGA-NAT@M and PLGA-NAT@M1 could gradually release NAT and reduce the clearance of the ocular surface. Macrophage membranes enhanced the antifungal activity of PLGA-NAT. Furthermore, the membrane coated with macrophage increased the biocompatibility and decreased the corneal toxicity of nanoparticles. In vivo, PLGA-NAT@M1 significantly alleviated the severity of FK. In vitro, PLGA@M and PLGA@M1 reduced the protein levels of inflammatory cytokines after fungal stimulation. The prepared PLGA-NAT@M1 has good physical properties and biosafety. It could evade ocular surface clearance, release NAT gradually, and achieve high antifungal and anti-inflammatory efficiencies to FK. Macrophage membrane-coated nanoparticles clinically have high application potential to the treatment of FK.

Scalable fabrication of vertically arranged Bi2Se3 crossbar arrays for memristive device applications

Despite the unique advantages of the memristive switching devices based on two-dimensional (2D) transition metal dichalcogenides, scalable growth technologies of such 2D materials and wafer-level fabrication remain challenging. In this work, we present the gold-assisted large-area physical vapor deposition (PVD) growth of Bi2Se3 features for the scalable fabrication of 2D-material-based crossbar arrays of memristor devices. This work indicates that gold layers, prepatterned by photolithography processes, can catalyze PVD growth of few-layer Bi2Se3 with 100-folds larger crystal grain size in comparison with that grown on bare Si/SiO2 substrates. We also present a fluid-guided growth strategy to improve growth selectivity of Bi2Se3 on Au layers. Through the experimental and computational analyses, we identify two key processing parameters, i.e., the distance between Bi2Se3 powder and the target substrate and the distance between the leading edges of the substrate and the substrate holder with a hollow interior, which plays a critical role in realizing large-scale growth. By optimizing these growth parameters, we have successfully demonstrated cm-scale highly-selective Bi2Se3 growth on crossbar-arrayed structures with an in-lab yield of 86%. The whole process is etch- and plasma-free, substantially minimizing the damage to the crystal structure and also preventing the formation of rough 2D-material surfaces. Furthermore, we also preliminarily demonstrated memristive devices, which exhibit reproducible resistance switching characteristics (over 50 cycles) and a retention time of up to 106 s. This work provides a useful guideline for the scalable fabrication of vertically arranged crossbar arrays of 2D-material-based memristive devices, which is critical to the implementation of such devices for practical neuromorphic applications.

Metabolomics of Chinese Hamster Ovary Cells.

Increasing demand of protein biotherapeutics produced using Chinese hamster ovary (CHO) cell lines necessitates improvement in the production yield of the bioprocess. Various cell engineering, improved media formulation and process-designbased approaches utilizing the power of OMICS technologies, specifically, genomics and proteomics, have been employed; however, the potential of metabolomics largely remains unexplored. Metabolomics enables the detection, identification, and/or quantitation of small molecules, commonly known as metabolites, in and around the cells and may help to unlock the cellular molecular mechanism(s) that regulates cell growth and productivity in the bioprocess and improves cellular performance during the bioprocess. Currently, liquid chromatography (LC)/gas chromatography (CG)- coupled with mass-spectrometry (MS) and nuclear magnetic resonance (NMR) spectroscopy are the most commonly used approaches for metabolomics. Therefore, in this chapter, we have discussed the standard procedures of investigating CHO metabolites using LC/GC-MS and/or NMR-based approaches.

Responsive Hydrogel-Based Drug Delivery Platform for Osteoarthritis Treatment

Osteoarthritis (OA) is the most prevalent chronic joint disorder and is a major cause of disability among the elderly population. The degeneration and damage of articular cartilage associated with OA can result in a diminished range of motion in joints, subsequently impacting fundamental activities such as ambulation, standing, and grasping objects. In severe cases, it may culminate in disability. Traditional pharmacological treatments are often accompanied by various side effects, while invasive surgical procedures increase the risk of infection and thrombosis. Consequently, identifying alternative new methods for OA treatment remains a formidable challenge. With advancements in responsive hydrogel drug delivery platforms, an increasing number of strategies have emerged to enhance OA treatment protocols. Injectable response hydrogel drug delivery platforms show many advantages in treating OA, including improved biocompatibility, prolonged drug release duration, elevated drug loading capacity and enhanced sensitivity. This article reviews the recent progress of injectable responsive hydrogel drug delivery platform for OA treatment over the past few years. These innovative methodologies present new strategies and directions for future OA treatment while summarizing a series of challenges faced during the clinical transformation of injectable response hydrogel drug delivery platforms. Overall, injectable responsive hydrogel drug delivery platforms show great potential in treating OA, especially regarding improving drug retention time and stimulus-responsive release at the lesion sites. These innovative methods provide new hope for future OA treatment and point the way for clinical applications.

A New Feasible Opportunity for Recycling Lead and Silver from Zinc Plant Residues by Flotation

Millions of tons of zinc plant leach residues (ZPLR) have been stockpiled in Iranian hydrometallurgical zinc plants during the last few decades. Due to the low grades of zinc, lead, and silver in these residues, these residues have been abandoned without treatment. The authors of this paper studied zinc plant leach residues (ZPLR) to propose a flotation process for separating and producing lead and silver concentrate. A response surface methodology (RSM) was employed to obtain six models for optimizing the best conditions for lead recovery, lead grade, zinc recovery, zinc grade, silver recovery, and silver grade. In these models, the effect of the different main variables, including density, flotation time, pH, sodium sulfide dosage, and potassium amyl xanthate dosage, was investigated to optimize grades and recoveries. The studied ZPLRs were categorized into two types based on the disposal time, including new and old residues. The chemical analysis showed that the grades of lead, zinc, and silver in the new residues are higher than in the old residues. In a previous mineralogical study, it was found that silver forms in lead and zinc minerals as a solid solution within their structures. The resulting 3D graphs showed that the interacting variables have significant effects on responses. The ANOVA analysis exhibited the order of model significance to be lead grade (F-value of 36.46) > silver grade (19.76) > lead recovery (7.88) > zinc grade (5.63) > silver recovery (5.58) > zinc recovery (4.83). Based on these models, under the conditions of 1126.26 g/cm3 density, 20.83 min retention time, 9.9 pH, 6 kg/t sodium sulfide, and 749.66 g/t potassium amyl xanthate dosage for a new residue type, the recoveries of lead, zinc, and silver were determined to be 51.10%, 11.13%, and 72.85%, with grades of 38.87% Pb, 8.46% Zn, and 1209.11 g/t Ag, respectively. According to the feasibility study results, the presented work is reasonable in terms of technical, economic, and investment potential.

Kinetics of dietary fibers in a fat sand rat: importance of the digestive tract isolating structures and food quality

The pass of feed through the digestive tract in a herbivorous rodent with a single-chamber gemiglandular stomach, the fat sand rat Psammomys obesus, was studied by multiple marking of the food with inert plastic markers. The total mean retention time of markers in the digestive tract (DT), as well as in the stomach and caecum separately, was determined. The peculiarities of the digesta kinetics depending on the morphology of the digestive tract, diet and the time of markers intake were clarified. The total time for removing markers from DT in the fat sand rat reaches 36 hours. The mean retention time of markers in DT was determined as a whole (17–18 hours), as well as separately in the forestomach (7–9 hours) and caecum (7–12 hours). The uneven passage of feed has been revealed, which is considered as an important mechanism for maximizing the extraction of nutrients from plants, including microbial fermentation of structural carbohydrates of the food.

Intravenous administration of gold nanoparticles in rats exhibit alterations in sphingomyelins, bile acids, sphingolipids, and cholesterol esters levels

AbstractNanoparticles (NP) have gained significant attention in biomedical research due to their unique properties and potential applications in drug delivery, imaging, and diagnostics. Gold (AuNPs) and silver (AgNPs) NPs are among the important nanoplatforms that received extensive attention recently for various biomedical applications. Understanding the complex interaction of these NP in biological systems is essential to unveil their pharmacological, Pharmacokinetic and toxicological attributes. Metabolomics has proven invaluable in providing detailed insights into NP’s biodistribution, metabolic effects, and potential toxicity. This study aims to investigate the underlying metabolic pathways affected by in vivo exposure to NP using a robust metabolomics approach. In this work, spherical polyethylene glycol (PEG) modified AuNPs (13 nm, diameter) or AgNPs (20 nm, diameter) were synthesized and dosed into rats via intravenous route to study the associated metabolic changes. Rats (n = 14) were divided into three groups: control (n = 2), AuNPs (n = 6) and AgNPs (n = 6), to mimic potential biomedical exposure scenarios. Duplicate serum samples were collected 24 h post-dosing, and comprehensive metabolite profiling was performed using liquid chromatography-mass spectrometry (LC-MS/MS) and flow injection analysis-mass spectrometry (FIA-MS/MS). Metabolite extraction followed the MxP Quant 500 Kit protocol, with chromatographic separation using the Xevo TQS system. Metabolite identification and quantification were conducted with isotopically labelled internal standards and multiple reaction monitoring (MRM), utilizing optimized conditions under mass spectrometry (MS) as provided by Biocrates. Annotation of metabolites was determined by retention times and specific MRMs for each compound. Results indicate that AuNPs treatment significantly impacted several metabolic pathways. Notably, there was an increase in sphingomyelin (SM 34:2) levels (estimate 0.23, p ≤ 0.001), which are critical for cell membrane structure and signalling. Additionally, a decrease in glycochenodeoxycholic acid levels was also triggered by treatment with AuNPs, suggesting modulation of bile acid metabolism with potential effects on lipid homeostasis. Furthermore, treatment with AuNPs caused significant alterations in cholesterol ester levels, essential for lipid storage and transport, indicating disruptions in these mechanisms. These metabolic changes suggest that gold nanoparticles can disrupt fatty acid metabolism, pyrimidine/purine metabolism, and amino acid synthesis. These findings contribute to the growing understanding of nanoparticle toxicity profile and underscore the need for further research to ensure the safe application of nanoparticles in biomedical and other fields.

Development of microflow ultra high performance liquid chromatography-mass spectrometry metabolomic assays for analysis of mammalian biofluids

Introduction and objectivesThe application of untargeted metabolomics assays using ultra high performance liquid chromatography-mass spectrometry (UHPLC-MS) to study metabolism in biological systems including humans is rapidly increasing. In some of these studies there is a requirement to collect and analyse low sample volumes of biofluids (e.g. tear fluid) or low cell and tissue mass samples (e.g. tissue needle biopsies). The application of microflow, capillary or nano liquid chromatography (≤ 1.0 mm column internal diameter (i.d.)) theoretically should accomplish a higher assay sensitivity compared to analytical liquid chromatography (2.1–5.0 mm column internal diameter). To date, there has been limited research into microflow UHPLC-MS assays that can be applied to study samples of low volume or mass.MethodsThis paper presents three complementary UHPLC-MS assays (aqueous C18 reversed-phase, lipidomics C18 reversed-phase and Hydrophilic Interaction Liquid Chromatography (HILIC)) applying 1.0 mm internal diameter columns for untargeted metabolomics. Human plasma and urine samples were applied for the method development, with porcine plasma, urine and tear fluid used for method assessment. Data were collected and compared for columns of the same length, stationary phase and stationary phase particle size but with two different column internal diameters (2.1 mm and 1.0 mm).Results and conclusionsAll three assays showed an increase in peak areas and peak widths when applying the 1.0 mm i.d. assays. HILIC assays provide an advantage at lower sample dilutions whereas for reversed phase (RP) assays there was no benefit added. This can be seen in the validation study where a much higher number of compounds were detected in the HILIC assay. RP assays were still appropriate for small volume samples with hundreds of compounds being detected. In summary, the 1.0 mm i.d. column assays are applicable for small volume samples where dilution is required during sample preparation.

Rapid QC-MS: Interactive Dashboard for Synchronous Mass Spectrometry Data Acquisition Quality Control.

Consistently collecting high-quality liquid chromatography-coupled tandem mass spectrometry (LC-MS/MS) data is a time-consuming hurdle for untargeted workflows. Analytical controls such as internal and biological standards are commonly included in high-throughput workflows, helping researchers recognize low-integrity specimens regardless of their biological source. However, evaluating these standards as data are collected has remained a considerable bottleneck─in both person-hours and accuracy. Here we present Rapid QC-MS, an automated, interactive dashboard for assessing LC-MS/MS data quality. Minutes after a new data file is written, a browser-viewable dashboard is updated with quality control results spanning multiple performance dimensions such as instrument sensitivity, in-run retention time shifts, and mass accuracy drift. Rapid QC-MS provides interactive visualizations that help users recognize acute deviations in these performance metrics, as well as gradual drifts over periods of hours, days, months, or years. Rapid QC-MS is open-source, simple to install, and highly configurable. By integrating open-source Python libraries and widely used MS analysis software, it can adapt to any LC-MS/MS workflow. Rapid QC-MS runs locally and offers optional remote quality control by syncing with Google Drive. Furthermore, Rapid QC-MS can operate in a semiautonomous fashion, alerting users to specimens with potentially poor analytical integrity via frequently used messaging applications. Initially developed for integration with Thermo Orbitrap workflows, Rapid QC-MS offers a fast, straightforward approach to help users collect high-quality untargeted LC-MS/MS data by eliminating many of the most time-consuming steps in manual data curation. Download for free: https://github.com/czbiohub-sf/Rapid-QC-MS.

The Fabrication of Polyimide-Based Tunable Charge Traps Ternary Memristors Doped with Ni-Co Coated Carbon Composite Nanofibers

In the dynamic fields of information science and electronic technology, there is a notable trend towards leveraging carbon materials, favored for their ease of synthesis, biocompatibility, and abundance. This trend is particularly evident in the development of memristors, benefiting from the unique electronic properties of carbon to enhance device performance. This study utilizes sensitized chemical evaporation and spin-coating carbonization techniques to fabricate nickel-cobalt coated carbon composite nanofibers (SC-NCMNTs). Novel polyimide (PI) matrix composite memory devices were fabricated using in situ polymerization technology. Transmission electron microscopy (TEM) and micro-Raman spectroscopy analyses validated the presence of dual interface structures located between the Ni-Co-MWNTs, carbon composite nanofibers, and PI matrix, revealing a significant number of defects within the SC-NCMNTs/PI composite films. Consequently, this results in a tunable charge trap-based ternary resistive switching behavior of the composite memory devices, exhibiting a high ON/OFF current ratio of 104 and a retention time of 2500 s at an operating voltage of less than 3 V. The mechanism of resistive switching is thoroughly elucidated through a comprehensive charge transport model, incorporating molecular orbital energy levels. This study provides valuable insights for the rational design and fabrication of efficient memristors characterized by multilevel resistive switching states.

Chromatographic Determination of Permeability-Relevant Lipophilicity Facilitates Rapid Analysis of Macrocyclic Peptide Scaffolds.

Hydrocarbon-determined shake-flask measurements have demonstrated great utility for optimizing lipophilicity during early drug discovery. Alternatively, chromatographic methods confer reduced experimental error and improved handling of complex mixtures. In this study, we developed a chromatographic approach for estimating hydrocarbon-water shake-flask partition coefficients for a variety of macrocyclic peptides and other bRo5 molecules including PROTACs. The model accurately predicts experimental shake-flask measurements with high reproducibility across a wide range of lipophilicities. The chromatographic retention times revealed subtle conformational effects and correlated with the ability to sequester hydrogen bond donors in low dielectric media. Estimations of shake-flask lipophilicity from our model also accurately predicted trends in MDCK passive cell permeability for a variety of thioether-cyclized decapeptides. This method provides a convenient, high-throughput approach for measuring lipophilic permeability efficiency and predicting passive cell permeability in bRo5 compounds that is suitable for multiplexing pure compounds or investigating the properties of complex library mixtures.

Seasonal Variations in the Thermal Stratification Responses and Water Quality of the Paldang Lake

We evaluated the thermal and chemical stratifications of Paldang Lake using Schmidt’s stability index (SSI) and the chemical stratification index (IC-i) with weekly data from 2013 to 2022. The temporal trends of stratification were analyzed alongside correlations with meteorological, hydrological, and water quality variables. Thermal stratification intensified with rising air temperature and sunshine duration, while hydrological factors like discharge and retention time affected SSI during periods with less than five days of water retention. During summer, fewer occurrences of intense rainfall or early rainfall before August led to stronger stratification. In fall, nutrient influx from external sources during summer stimulated algal growth, increasing Chlorophyll-α (Chl-α) concentrations. Summer rainfall had a significant impact on the strength and duration of stratification in Paldang Lake. Annual rainfall patterns and subsequent changes in discharge were key factors affecting the physical environment of the lake, which in turn determined water quality and the extent of algal blooms. We provide insights into the seasonal stratification and water quality variations in temperate river-type reservoirs like Paldang Lake. SSI and IC-i from this research can be applied to understand stratification and mixing dynamics in other lakes.

Application of Bioelectrochemical System in Nitrogen Removal via Simultaneous Autotrophic Nitrification and Denitrification from Wastewater

AbstractBioelectrochemical systems (BES) is a new and expanding technology that can simultaneously convert chemical energy into electrical energy by removing nutrients. The present study investigated the BES in removing nitrogen compounds and produce electricity. To this end, a BES reactor with two chambers of cathode and anode and nafion 117 membrane was used as a separator between the two chambers. Then, the BES performance at different concentrations of COD and primary ammonium at different retention times was investigated to remove nitrogen compounds and organic matter. Voltage, current and power density were measured. The results showed that the maximum COD removal efficiency was 73.2 % for the substrate concentration of 2000 mg/L, which decreased to 72.6 % when the substrate concentration increased to 10000 mg/L. The maximum removal efficiency of nitrogen compounds was 83.4 % at COD 10000 mg/L and the initial ammonium concentration was 50 mg/L. The maximum voltage, current and power density in this phase were 391 mV, 460 mA/m2, 63/48 mW/m2, respectively. The results of the study showed that BES can be used as a suitable method to remove high amounts of ammonium in wastewater and organic materials and simultaneously produce electricity.

Scientifc Validation and Chromatographic Method Development for the Estimation of Piperine in Herbal Formulation Babbularishta: A Quality Control Strategy for Critical Quality Attributes

Background: Babbularishta is an Ayurvedic medicine in liquid form used for the treatment of phthisis, skin diseases, urinary disorders,, and breathing problems. It is also beneficial in cases of blood disorders, acne, dermatitis, hemoptysis, lung injury, asthma, persistent cough, whooping cough, etc. Objective: The functional role of this study is to develop a simple, novel, precise, accurate, reliable, and selective RP-HPLC method for the estimation of piperine content in herbal drug formulations (Babbularista). Methods: A traditional approach to method development could fail to meet the desired separation. Consideration of the current regulatory requirement for analytical method development and RP-HPLC method for routine analysis of piperine in the herbal formulation has been optimized using an analytical Quality by Design (QbD) approach. Three laboratory formulations and three marketed preparations of Babularishta were investigated for organoleptic parameters, physicochemical parameters, and validation. The mobile phase composition (methanol and water % as A), pH (B), and flow rate (mL/min as C) were selected as independent variable,. In contrast, retention time (min. as Y2), area (AU as Y1) is selected as dependent variables. Results: The fingerprinting method was developed and optimized by using the AQbD approach. Piperine content was found to be in Piper nigrum (Marica) 3.01±0.01527 % w/w and in Piper longum (Pipali) 2.74±0.01154% w/w in Babbularista. Conclusion: An attempt has been made to develop quality control parameters of Babbularista by developing a suitable and sensitive HPLC methods for the quantitation of piperine in herbal drug formulations (Babbularista). The developed method was found to be simple, accurate, precise,, and economical for the estimation of piperine in herbal formulations.

Measurement Uncertainty and Validation for Quantification of Marijuana Metabolite: (−)-11-nor-9-Carboxy-Δ9-THC in Human Urine by GC-MS/MS

Background: Since the International Olympic Committee (IOC) was established, sports doping control analyses have revealed a high rate of positive cases for cannabinoids. Cannabinoids were banned in all sports where they were used in competition as per the Prohibited List published annually. Further, it was also included in the threshold drug category. Consequently, developing a reliable method for urine Cannabinoids metabolite quantification plays a pivotal role in sports dope testing. Objective: This work aimed to develop and validate a reliable, cost-effective, robust gas chromatography-tandem mass spectrometry method for detecting (−)-11-nor-9-Carboxy-Δ9- THC component in human urine samples, in compliance with ICH and WADA guidelines. Method: The sample preparation was done by enzymatic hydrolysis for deconjugation, further proceeded with solid phase extraction (SPE), liquid-liquid extraction (LLE), and using an XAD2 column, and N-methyl trimethylsilyl trifluoroacetamide (MSTFA) for derivatization. Results: The linearity was obtained in a range of 50–300 ng/mL, and the correlation coefficient was found to be higher than 0.99. Throughout the entire validation study, the difference in Retention Time (RT) for the analyte, including the Internal Standard (IS), was shown to be less than 1.0%. The quantification limit (LOQ) was calculated at a level of 50 ng/mL in human urine samples for the 3 most abundant ion transitions. The detection limit (LOD) was established at 4 ng/mL. Conclusion: The accuracy, precision, linearity, recovery, quantification limit, and selectivity by GC-MS/MS technique were found acceptable and well satisfactory while following the ICH guidelines. The developed method has been proven to be fit for purpose in accordance with the enforced Guidelines of WADA.

Leveraging the potential of 1.0-mm i.d. columns in UHPLC-HRMS-based untargeted metabolomics.

Untargeted metabolomics UHPLC-HRMS workflows typically employ narrowbore 2.1-mm inner diameter (i.d.) columns. However, the wide concentration range of the metabolome and the need to often analyze small sample amounts poses challenges to these approaches. Reducing the column diameter could be a potential solution. Herein, we evaluated the performance of a microbore 1.0-mm i.d. setup compared to the 2.1-mm i.d. benchmark for untargeted metabolomics. The 1.0-mm i.d. setup was implemented on a micro-UHPLC system, while the 2.1-mm i.d. on a standard UHPLC, both coupled to quadrupole-orbitrap HRMS. On polar standard metabolites, a sensitivity gain with an average 3.8-fold increase over the 2.1-mm i.d., along with lower LOD (LODavg 1.48ng/mL vs. 6.18ng/mL) and LOQ (LOQavg 4.94ng/mL vs. 20.60ng/mL), was observed. The microbore method detected and quantified all metabolites at LLOQ with respect to 2.1, also demonstrating good repeatability with lower CV% for retention times (0.29% vs. 0.63%) and peak areas (4.65% vs. 7.27%). The analysis of various samples, in both RP and HILIC modes, including different plasma volumes, dried blood spots (DBS), and colorectal cancer (CRC) patient-derived organoids (PDOs), in full scan-data dependent mode (FS-DDA) reported a significant increase in MS1 and MS2 features, as well as MS/MS spectral matches by 38.95%, 39.26%, and 18.23%, respectively. These findings demonstrate that 1.0-mm i.d. columns in UHPLC-HRMS could be a potential strategy to enhance coverage for low-amount samples while maintaining the same analytical throughput and robustness of 2.1-mm i.d. formats, with reduced solvent consumption.

Experimental and theoretical investigation of benzothiazole oxidation by OH in air and the role of O2.

Benzothiazole (BTH) and its derivatives are amongst a group of emerging contaminants that are widely distributed in the environment due to their extensive use in many different consumer products. In air, reaction with the hydroxyl radical (OH) is expected to be a major loss process for BTH in the gas phase, but the kinetics and mechanisms are unknown. Here, we report a combination of experiments and theory to determine both the rate constant and products of the reaction of OH with the smallest member of the series, benzothiazole, in the gas phase. The mechanism first involves an attack by OH on BTH to produce several OHBTH intermediates. This is followed by O2 reactions with OHBTH, leading to several stable products successfully predicted by theory. Relative rate studies at 1 atm in air and 298 K using benzene as a reference gave a rate constant for the BTH + OH reaction of 2.1 ± 0.1 × 10-12 (1σ) cm3 per molecule per s, which translates to a lifetime in air of 5.5 days at 1 × 106 OH cm-3. Four hydroxybenzothiazole products reflecting attack on different carbon atoms of the benzene ring were measured (n-OHBTH, where n = 4, 5, 6, 7), with the relative product yields well predicted by the calculated formation energies of the pre-reaction OH⋯BTH complex. Attack of OH on the -CH of the thiazole ring leads to the formation of 2-OHBTH, representing a smaller fraction of the overall reaction, and is shown to proceed through a more complex mechanism than attack on the benzene ring. A theoretical approach to predicting chromatographic retention times of the products based on solvation free energies (ΔGsolv) was successful for most of the products. These studies illustrate how the powerful combination of experiment and theory can be used to predict products of atmospheric oxidation of emerging contaminants and ultimately used to assess their impacts on the environment.

Unveiling synergistic enhancement mechanism of nitrogen removal in surface flow constructed wetlands: Utilizing iron scraps and elemental sulfur as integrated electron donors

Lacking electron donors generally causes poor denitrification performance in constructed wetlands (CWs). In this study, iron scraps (ISs) and elemental sulfur (S0) were employed as electron donors in different surface flow constructed wetlands (SFCWs): control (C-SF), ISs added (Fe-SF), S0 added (S-SF), and ISs and S0 combined (Fe + S-SF) to investigate the performance and mechanism of nitrogen (N) removal through continuous flow and batch experiments. The impact of hydraulic retention times (HRTs) and temperatures on N removal was explored. The combined use of ISs and S0 significantly improved nitrate (NO3− -N) removal in Fe + S-SF compared to the other SFCWs. During the 3-d HRT at 25 °C, the average NO3− -N removal efficiency in Fe + S-SF reached the highest value of 71.66 ± 12.54%, reducing NO3− -N concentrations from 12.03 mg/L to 3.47 mg/L. The results of the batch experiments revealed an N removal pattern that aligned with the findings of the continuous flow experiment. The microbial community analysis revealed a selective enrichment of key functional genera (e.g., Ferritrophicum and Dechloromonas), contributing to enhanced N removal in Fe + S-SF. These findings suggest that the synergistic use of ISs and S0 can achieve better denitrification efficiency and potentially be utilized for enhanced N removal from low C/N wastewater.

Pitaya-Inspired Metal-Organic Framework Nanozyme for Multimodal Imaging-Guided Synergistic Cuproptosis, Nanocatalytic Therapy, and Photothermal Therapy.

Nature often provides invaluable insights into technological innovation and the construction of nanomaterials. Inspired by the pitaya fruit's strategy of wrapping seeds within its pulp to enhance seed survival, a unique nanocomposite based on metal-organic framework (MOF)-encapsulated CuS nanoparticles (NPs) is developed. This design effectively addresses the challenge of short retention time afforded by CuS NPs for therapeutic and imaging purposes. The MOF acts as the "pitaya pulp" protecting the internal CuS NPs ("pitaya seeds"), thereby increasing their retention time in vivo. This system exhibits triple-enzyme-mimicking activities and is proposed for application in photoacoustic and magnetic resonance imaging-guided therapies, including chemodynamic therapy, photothermal therapy, and cuproptosis-related therapy. The exceptional enzyme-mimicking activities of superoxide dismutase, catalase, and peroxidase not only produce oxygen to alleviate hypoxia but also generate a reactive oxygen species (ROS) storm for effective tumor destruction. By combining these multienzymatic properties, superior photothermal performance, and Cu-induced cuproptosis, nanozyme-treated mice exhibited an 84% inhibition of tumor growth-approximately double the effect observed in mice treated with CuS NPs alone. This study presents a smart strategy for integrating imaging with therapeutic modalities, achieving exceptional outcomes for precise imaging-guided tumor therapy.