Analytical and Bioanalytical Chemistry最新文献

Interest in bile acids (BAs) is growing due to their emerging role as signaling molecules and their association with various diseases such as colon cancer and metabolic syndrome. Analyzing BAs requires chromatographic separation of isomers, often with long run times, which hinders BA analysis in large studies. Here, we present a high-throughput method based on liquid chromatography-tandem mass spectrometry to quantify BAs in mouse samples. After acidic protein precipitation in the presence of a comprehensive mixture of stable isotope-labeled internal standards (SIL-ISs), BAs are separated on a biphenyl column by gradient elution at basic pH. Quantification is performed using a six-point calibration curve. Except for the separation of β- and ω-muricholic acid (MCA) species, a rapid separation of 27 BA species was achieved in a run time of 6.5 min. Plasma quality controls (QCs) were used to evaluate intra- and inter-day precision. The CV was less than 10% for most BA species and exceeded 20% only for glycohyodeoxycholic (GHDCA) and taurohyodeoxycholic acid (THDCA) due to the lack of a corresponding SIL-IS. The limit of quantification (LoQ) was tested using diluted QCs and was found to be compromised for some BA species as a result of insufficient isotopic purity of the SIL-IS, leading to significant interference with the respective analyte. Finally, we tested the mouse sample material requirements for plasma, bile, and liver samples and determined BA concentrations in C57/BL6N wild-type mice. In conclusion, the LC-MS/MS method presented here permits a rapid and reproducible quantification of the major murine BAs.

After recovering from COVID-19, many patients experience "long COVID" symptoms. Existing research has predominantly focused on moderate to severe cases, with limited studies examining mild cases and recurrent infections. The circulating low-molecular-weight (LMW) peptidome, involving lipid metabolism, coagulation, and immune pathways, is crucial for understanding COVID-19's long-term effects. We developed a peptidomics workflow utilizing solid-phase extraction with highly wrinkled GO-Fe₃O₄ composite materials (HWGO-F) and nanoLC-MS/MS detection. By altering the pH, HWGO-F enhances plasma peptide adsorption and purification. Compared to traditional methods, our workflow offers improved detection depth and reproducibility for over 70% of peptide signals with CV < 20%. We investigated plasma peptide profiles in mild COVID-19 patients post-recovery from single or second infections. The findings indicate persistent abnormalities in initial COVID-19 infections' plasma peptide profiles, gradually diminishing over time. Secondary infections prolong recovery. Disrupted functions include lipid metabolism, coagulation and complement cascades, and infection-related pathways. Lipid metabolism may normalize within 3 months, while coagulation and immune abnormalities can last 3-6 months. After secondary infections, lipid metabolism irregularities may last at least 1 month, with extended coagulation and immune imbalances. These results provide a theoretical foundation for understanding the widespread occurrence of long COVID and guide recovery care for mild cases.

This work presents the development and optimisation of an amperometric biosensor for determining aspartate aminotransferase (AST) activity in blood serum, using glutamate oxidase and platinum disc electrodes. AST is a key biomarker for diagnosing cardiovascular and liver diseases. The biosensor's bioselective membrane composition and formation protocol and the working solution (aspartate 8 mM, α-ketoglutarate 2 mM, pyridoxal-5-phosphate 100 µM) were optimised. The sensor demonstrated high selectivity, stability (70% retention over 2 months at - 18 °C), and sensitivity (2.37 nA min⁻¹ per 10 U L⁻¹), with a dynamic range of 0-500 U L⁻¹ and a limit of detection of 1 U L⁻¹. Comparative analysis showed the calibration curve method outperforms the standard addition method for AST measurement in serum samples. Additionally, a reference spectrophotometric technique was adapted for AST level determination, showing a strong correlation (r = 0.989) with the biosensor results. This research offers a fast, affordable, and accurate tool for early check-ups of liver and heart conditions. The biosensor's flexibility and ease of use make it suitable for further development into point-of-care testing and personalised healthcare techniques.

A fully automated dual-column purification procedure for Zn from biological samples, designed for subsequent Zn isotopic analysis, is presented that utilizes the prepFAST MC™ system (Elemental Scientific), DGA resin (TrisKem International), and TK201 resin (TrisKem International). The procedure developed enables the unattended processing of 20 samples per day and is characterized by low and reproduceable blanks (< 1.5 ng), no carry-over or memory effect, high reusability (> 50 times), high Zn yields 100.1% ± 5.3% (2 SD, N = 22), and strong robustness to matrix variations across biological samples (bone, liver, hair, blood). Additionally, Zn isotopic analysis using MC-ICP-MS showed no significant on-column fractionation. The measured δ⁶⁶Zn/⁶⁴Zn_IRMM values for NIST SRM 1400 (0.67‰ ± 0.07‰, U, k = 2), NIST SRM 1486 (0.91‰ ± 0.06‰, U, k = 2), NIST SRM 1577c (- 0.45‰ ± 0.05‰, U, k = 2), ERM-DB001 (- 0.35‰ ± 0.05‰, U, k = 2), GBW09101 (- 0.32‰ ± 0.08‰, U, k = 2), and SeroNorm whole blood L-3 (-0.15 ‰ ± 0.05 ‰, U, k = 2) are consistent with published values. The procedure developed makes Zn, an analytically challenging isotope system, more accessible, feasible, and reliable for a broader range of users while enabling high sample throughput.

Oxylipins are diverse bioactive signaling molecules, which occur in very low concentrations in complex matrices, posing challenges in achieving consistent and sensitive analysis. UHPLC-MS/MS is the preferred technique to separate and quantify these molecules, often optimized using a time-consuming trial-and-error approach. In this study, we applied the design of experiments (DoE) approach to systematically investigate the ionization properties of multiple oxylipin species. Fractional factorial and central composite designs were employed to detect relevant instrument parameters and optimize signal intensity in ESI-MS/MS analysis. Response surface modeling revealed distinct ionization and fragmentation behaviors between polar and apolar oxylipins, driven by their responses to interface temperature and collision-induced dissociation (CID) gas pressure. Particularly, prostaglandins and lipoxins benefit from higher CID gas pressure and lower temperatures compared to the lipophilic HODEs and HETEs to achieve optimal intensity in multiple reaction monitoring analysis. While global source parameters were optimized, analyte-specific entrance/exit potentials and collision energies required individual adjustments. The final method was applied to analyze seven oxylipin classes including leukotrienes, prostaglandins, lipoxins, resolvins, HETEs, HODE_S, and HoTrEs. Although improvements in lower limits of quantification were modest (< 1 pg on-column), signal-to-noise ratios increased two-fold for lipoxins and resolvins and three- to four-fold for leukotrienes and HETEs, enhancing detection at trace levels. This DoE-guided strategy provides a powerful tool to improve UHPLC-MS/MS analysis of oxylipins across various instrument vendors, guiding the way towards inter-laboratory comparability.

Thrombin overexpression in serum serves as a critical biomarker and is implicated in several diseases associated with significant morbidity and mortality. Existing techniques for thrombin detection are time-consuming and require sophisticated equipment and extensive sample preparation procedures, which further delay the detection and increase the cost of the procedure. Early and accessible diagnosis at the point of care, especially in limited-resource countries, represents the first step of clinical interventions. To overcome these limitations, we have proposed an innovative, sustainable paper-based electrochemical detection platform for thrombin. In this work, a sustainable paper-based aptasensor was rationally designed, characterized, evaluated against conventional gold standard plastic-based substrates, and applied to human serum, yielding a detection limit of ~ 60 pM. The present method provides an efficient and user-friendly way for the detection of thrombin and potentially leading to better management and treatment outcomes for patients.

The site-specific antibody-drug conjugates (ADCs), particularly those utilizing the engineered cysteine in Fc fragments of mAbs (THIOMAB™ antibodies), have emerged as a novel class of biotherapeutics for cancer treatment. The engineered cysteine residues in these antibodies are capped by cysteine or glutathione through a disulfide bond. Prior to conjugation with linker-payloads, these caps need to be removed through a reduction process. However, monitoring the efficiency of the decapping process has been challenging due to the lack of effective analytical methods. Intact reversed-phase liquid chromatography-mass spectrometry and hydrophobic interaction chromatography methods failed to separate decapped and capped intact THIOMAB™ mAbs in our study. Instead the fragmentation of mAbs provided a novel strategy to analyze the decapping effiency. After cleavage using a hinge specific enzyme, the generated Fc fragments with and without cysteine and/or glutathione caps displayed different hydrophobicity and were well separated by RPLC, allowing quantitative determination of the decapping efficiency. Enzymes that cleave both above and below the hinge disulfide bonds were tested. The use of FabALATICA can determine percentages of molecules with 0, 1, and 2 cysteine and/or glutathione caps, respectively, regardless of whether the antibody contains the hinge LALA mutations. On the other hand, FabRICATOR enzyme can only be utilized for antibodies without LALA mutations for the overall decapping percentage and cannot be used to estimate intact antibody each with 0, 1, and 2 caps. Therefore, FabALACTICA cleavage followed by RPLC provides a wider application of monitoring the decapping efficiency of all antibodies with the engineered cysteine in Fc.

Recently in the USA, kratom consumers increasingly report use of the plant for self-treatment of mood ailments, the lack of energy, chronic pain, and opioid withdrawal and dependence. Several alkaloids are present in kratom leaves, but limited data are available on their pharmacokinetics/pharmacodynamics, except for mitragynine. To support clinical studies, a high-performance liquid chromatography-tandem mass spectrometry assay for the simultaneous quantification of 11 kratom alkaloids in human plasma was developed and validated. For calibration standards and quality control samples, human plasma was fortified with alkaloids at varying concentrations, and 200 µL were extracted employing a simple one-step protein precipitation procedure. The extracts were analyzed using LC-MS/MS including electrospray ionization (ESI) in positive multiple reaction monitoring (MRM) mode. The lower limit of quantification was 0.5 ng/mL, and the upper limit of quantification was 400 ng/mL for all analytes. Inter-day analytical accuracy and imprecision ranged from 98.4 to 113% of nominal and from 3.9 to 14.7% (coefficient of variance), respectively. The analysis of plasma samples collected during a clinical trial administering capsules containing kratom leaf extract showed that most samples had quantifiable concentrations of mitragynine, 7-OH-mitragynine, speciogynine, speciociliatine, and paynantheine and that mitragynine, speciogynine, and speciociliatine accumulated in human plasma after daily administration over 15 days. An LC-MS/MS assay for the specific quantification of kratom alkaloids including mitragynine and its main metabolites was developed and successfully validated in human plasma. Human plasma samples collected following multiple oral administrations of a controlled Kratom extract documented accumulation of kratom alkaloids over 15 days.

Point-of-care testing methods are essential for the large-scale diagnosis and monitoring of bacterial infections. This study introduces an integrated platform designed for the simultaneous detection of pathogenic bacteria. Users can simply inject samples into the system, which then conducts the entire procedure in a fully automated manner, eliminating the need for external power sources, all within 60 min or less. The innovative paper-based microfluidic system is capable of lysing bacteria and integrating loop-mediated isothermal amplification (LAMP) with the CRISPR/Cas12a system, achieving this with minimal reagent usage on a single piece of paper. The reaction reagents are pre-fabricated as freeze-dried powder on the paper, allowing for long-term storage. A portable and cost-effective detection device has been designed to provide stable temperature control and analyze fluorescent signals, complementing the paper-based microfluidic system. This compact device measures 150 × 150 × 100 mm, weighs less than 1.8 kg, has an average power consumption of under 15 W, and supports external power supply. The device utilizes non-contact QR codes for information transmission, ensuring functionality even in areas without Internet connectivity. This platform is capable of simultaneously detecting five typical pathogenic microorganisms, with a detection limit of 1 copy/μL. It boasts several advantages, including miniaturization, lightweight design, low power consumption, portability, affordability, rapid detection, and ease of operation, making it highly suitable for on-site detection.