Search Results (216)

Circulating cell-free DNA (cfDNA) is an important biomarker for various cancer types, enabling a non-invasive testing approach. However, pre-analytical variables, including sample collection, tube type, processing conditions, and extraction methods, can significantly impact the yield, integrity, and overall quality of cfDNA. This study presents a comprehensive analytical validation of a magnetic bead-based, high-throughput cfDNA extraction system, with a focus on assessing its efficiency, reproducibility, and compatibility with downstream molecular applications. The validation was performed using a range of sample types: synthetic cfDNA spiked into DNA-free plasma, multi-analyte ctDNA plasma controls, Seraseq ctDNA reference material in a plasma-like matrix, extraction specificity controls, residual clinical specimen from patients, and samples from healthy individuals stored at room temperature or 4 °C for up to 48 h to assess stability. Extracted cfDNA was analyzed for concentration, percentage, and fragment size, using the Agilent TapeStation. Variant detection was evaluated using a next-generation sequencing (NGS) assay on the Seraseq ctDNA reference material. The results demonstrated high cfDNA recovery rates, consistent fragment size distribution (predominantly mononucleosomal and dinucleosomal), minimal genomic DNA (gDNA) contamination, and strong concordance between detected and expected variants in reference materials. The workflow also showed robust performance under different study parameters, variable sample conditions, including sample stability and integrity. Together, these findings confirm the efficiency and reliability of the evaluated cfDNA extraction system and underscore the importance of standardized pre-analytical workflows for the successful implementation of liquid biopsy for early cancer detection, therapeutic monitoring, and improved patient outcomes. Full article

The migration of hindered phenolic antioxidants from food contact materials (FCMs) into foodstuffs poses health risks due to endocrine disruption and organ toxicity. Hence, the development of a high-efficiency analytical method for hindered phenolic antioxidants is of great importance for food safety. This study developed a novel ultrasound-assisted dispersive solid-phase filter extraction (d-SPFE) coupled with green supercritical fluid chromatography (SFC) method for the simultaneous determination of six representative hindered phenolic antioxidants. Under optimized conditions, the method achieved high extraction efficiency, with the complete separation of all analytes within 10 min. A wide linearity range (0.02–2.0 μg/mL) was achieved, with coefficients of determination all greater than 0.9996. The limits of detection (LOD, S/N = 3) and limits of quantification (LOQ, S/N = 10) were 2.4–3.6 ng/mL and 8–12 ng/mL, respectively. Validation tests demonstrated precise spiked recoveries (89.4–101.6%), with intra-day and inter-day relative standard deviations (RSDs) all less than 10%. The d-SPFE-SFC synergy significantly outperforms conventional techniques in terms of analysis speed and eco-efficiency. Successful application to food simulants confirms its reliability in monitoring hindered phenolic antioxidant migration from FCMs. This green and rapid methodology will enable the direct assessment of migration risks. Full article

Fluridone is a pyrrolidone soil-sealing herbicide that has been widely used in cotton fields in Xinjiang in recent years. The purpose of this study was to establish a method for determining fluridone residues in cotton fields and to perform residue digestion tests, final residue analysis, and dietary risk assessment. Samples were extracted with acetonitrile, purified with primary secondary amine (PSA) and multi-walled carbon nanotubes (MWCNTs), and analyzed by high-performance liquid chromatography (HPLC). The results showed that in a certain concentration range, the concentration and peak area of fluridone showed a good linear relationship (R² > 0.99), with limit of detection (LOD) and limit of quantification (LOQ) values of 0.00090–0.00108 mg·kg⁻¹ and 0.0030–0.0033 mg·kg⁻¹, respectively. The relative standard deviation (RSD) values of fluridone were 0.46% to 4.57% at the spiked level of 0.1, 0.5, and 1.0 mg·kg⁻¹, respectively. The average daily recovery rate of fluridone was 85.08% to 95.07%. The residual levels of fluridone in cottonseed oil were below the safety threshold, indicating no significant dietary risk to consumers. Full article

Steatotic liver disease is a global health challenge that requires reliable and noninvasive diagnostic biomarkers. This research aimed to validate the analytical and clinical performance of a fibroblast growth factor 21 (FGF21) enzyme-linked immunosorbent assay (ELISA) kit using an automated immunoassay analyzer. Plasma FGF21 levels were measured using a commercial ELISA kit on an automated immunoassay analyzer. Validation included intra- and inter-assay precision, dilution linearity, spike recovery, lower limit of quantification (LLOQ), interference testing, and sample stability analysis. Clinical evaluation involved 97 patients who underwent abdominal ultrasound-based attenuation imaging for the diagnosis of hepatic steatosis. The assay demonstrated high analytical precision, with intra- and inter-assay coefficients of variation <15% and an LLOQ of 3.260 pg/mL. Dilution linearity, spike recovery, and interference tests confirmed the reliability of the assay, whereas stability tests highlighted the minimal effect of freeze-thaw cycles and storage conditions. Clinically, FGF21 levels correlated with attenuation coefficient (r = 0.44). Diagnostic performance indicated 84% sensitivity and 81% specificity at defined FGF21 thresholds for the diagnosis of hepatic steatosis. This research confirmed the reliable analytical and clinical performance of the FGF21 ELISA kit, reinforcing its potential as a diagnostic biomarker of hepatic steatosis. Full article

Hydrocortisone is a typical glucocorticoid commonly used in livestock production; however, its overuse can result in hormone residues in milk. Long-term consumption of such milk may lead to a series of health issues. Therefore, the timely and rapid detection of hydrocortisone in milk is crucial for protecting human health. In this study, a magnetic particle-based direct chemiluminescence immunoassay (MP-DCLIA) incorporating a streptavidin–biotin signal amplification system was developed for the rapid and high-throughput detection of hydrocortisone in milk. Automated operations reduce human error and enhance the accuracy and repeatability of tests. The assay can be completed in 12 min with a linear detection range of 13.09–261.71 μg/L, a limit of detection (LOD) of 4.94 μg/L, a limit of quantification (LOQ) of 14.84 μg/L, and intra- and inter-batch variations of less than 5%. The method demonstrated stability and exhibited no cross-reactivity with structural analogues. Spiked recoveries of milk samples ranged from 85.85% to 100.30%, with results strongly correlating with those obtained from LC-MS/MS. The MP-DCLIA offers rapidity, high efficiency, stability, and precision, making it a promising tool for practical testing applications. Full article

The rapid and ultrasensitive detection of Salmonella holds strategic significance for food safety surveillance and public health protection systems. This study innovatively developed a label-free biosensing platform based on the synergistic integration of Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)-Cas12a and the fluorescent deoxyribozyme Aurora for the efficient detection of foodborne Salmonella. The detection mechanism operates through a molecular cascade reaction: target-activated Cas12a protein specifically degrades Aurora deoxyribozyme via its trans-cleavage activity, thereby abolishing the enzyme’s catalytic capability to convert 4-methylumbelliferyl phosphate (4-MUP) into the highly fluorescent product 4-methylumbelliferone (4-MU). This cascade ultimately enables quantitative target analysis through fluorescence signal attenuation. Following systematic optimization of critical reaction parameters, the biosensing system demonstrated exceptional analytical performance: a detection limit of 1.29 CFU/mL with excellent linearity (R² = 0.992) spanning six orders of magnitude (1.65 × 10¹–10⁶ CFU/mL), along with high specificity against multiple interfering bacterial strains. Spike-and-recovery tests in complex food matrices (milk, chicken, and lettuce) yielded recoveries of 90.91–99.40% (RSD = 3.55–4.72%), confirming robust practical applicability. Notably, the platform design allows flexible detection of other pathogens through simple replacement of CRISPR guide sequences. Full article

Trifloxystrobin and bupirimate are widely used as fungicides for controlling powdery mildew in cucumber cultivation. Supervised field trials were conducted in 12 representative regions across China, following Good Agricultural Practices (GAP) guidelines, to investigate their residue patterns and potential dietary exposure risks. Cucumber samples were analyzed using a validated method involving extraction with acidified acetonitrile (2% acetic acid, v/v), cleanup with primary secondary amine (PSA) and graphitised carbon black (GCB), and quantification by high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). The method demonstrated excellent recovery rates (85–103%) throughout four spiking levels (0.01, 0.1, 0.3, and 1 mg/kg), with relative standard deviations (RSD) ≤ 4.8%. At 3 days after treatment, the residues of trifloxystrobin (including trifloxystrobin acid), bupirimate, and ethirimol in cucumbers were found to range from <0.01 to 0.013 mg/kg, <0.01 to 0.076 mg/kg, and <0.01 to 0.04 mg/kg, respectively. A chronic dietary risk assessment was conducted using a probabilistic model. The results showed an acceptable chronic risk (RQ_c ≤ 2.476%) for trifloxystrobin, bupirimate, and ethirimol across different sexes and ages, supporting the conclusion that the use of these fungicides in cucumber cultivation under the tested conditions was safe for Chinese consumers. More research was needed on children because they are at higher risk than other groups. Full article

Electrochemical methods show promise for wastewater treatment by removing pollutants, recovering nutrients, and generating hydrogen. To scale this technology, durable and affordable electrode materials are needed. This study evaluates aluminum 6061-T6, titanium grade II, ductile iron, and magnesium to understand their performance in promoting precipitation, gas production, and treating wastewater under several conditions. Electrodes were tested with ammonia-, magnesium-, and phosphate-spiked wastewater samples with induced precipitation at concentrations of 0.033 mol/L and 0.0033 mol/L; the liquid, gas, and precipitation phases were characterized. The results showed up to 35% reduction in ammonia, total phosphate recovery, and up to 70% reduction in magnesium. The cell generates hydrogen with purity levels of 95.6%, 96.1%, 87.9%, and 93.5% when utilizing iron, aluminum, titanium, and magnesium electrodes, respectively. The analyses of precipitants showed formation of vivianite crystals from iron, struvite precipitation from magnesium, and berlinite from aluminum. Overall, these results hold substantial promise for hydrogen generation from wastewater and potential for nutrient recovery and treatment. Full article

Vomitoxin is a member of the monotrichous mycotoxin family with a complex chemical structure and significant biological activity. This toxin has strong immunosuppressive toxic effects and can cause serious damage to human and animal health. In this study, an on-site immune detection method based on an immune SiO₂@QD fluorescent probe was developed, which realized the rapid and quantitative detection of emetic toxins in grains. Polyethyleneimine (PEI) is a polymer containing a large number of amino groups, and the binding of PEI to the surface of quantum dots can serve to regulate growth and provide functionalized groups. A SiO₂@QD nanotag with good dispersibility and a high fluorescence intensity was synthesized by combining a PEI interlayer on the surface of SiO₂ nanospheres. Utilizing the electrostatic adsorption of the amino group in PEI, CdSe/ZnS QDs were self-assembled on the surface of SiO₂ nanospheres. In the stability test, the SiO₂@QDs could maintain basically the same fluorescence intensity for 90 consecutive days in the dark at 4 °C, showing a high fluorescence stability. The fluorescence-enhanced QD immune probe was formed by coupling with anti-DON monoclonal antibodies through carbodiimide chemical synthesis. For the detection of spiked wheat flour samples, the immuno-SiO₂@QD fluorescent probe showed excellent sensitivity and stability, the detection limit reached 0.25 ng/mL, and the average recovery rate was 92.2–101.6%. At the same time, the immuno-SiO₂@QD fluorescent probe is simple to operate, is capable of rapid responses, and has great potential in the rapid detection of vomitoxins in grains. Full article

Due to the characteristics of high salt and high acidity of the electrolyte and the chemical reaction between thiourea (Tu) and metal ions, it is still a problem to quickly and accurately detect Tu concentration in copper electrolyte. An improved spectrophotometric method has been proposed by simplifying the extraction steps of the traditional extraction–spectrophotometry and reducing the dosage of extractant and buffer. The improved method, with a favorable R² of 0.9991, great precision of 1.67% and excellent spiked recovery of 102.19%, was not affected by the presence of gelatin and copper ions. Moreover, based on the spectrophotometry, a colorimetric method for rapid detection of Tu concentration in copper electrolyte was proposed. Using the standard color card produced enabled the expeditious determination of the concentration range of Tu in copper electrolyte. Since the gray value of the standard color card is linearly related to the Tu concentration, it is feasible to determine the Tu concentration by measuring the gray value of the test strip, and its accuracy was verified by spectrophotometry. The colorimetric method has satisfactory results in industrial practice. This study provides a novel approach for the rapid detection of Tu concentration in the copper electrolysis industry. Full article

In this work, a novel molecularly imprinted electrochemical sensor was proposed based on molecular imprinting technology for the detection of sulfamethazine. A glassy carbon electrode was modified with a composite material of carbon nanotubes and graphene quantum dots to effectively improve sensitivity. The molecularly imprinted electrochemical sensor was then prepared by electropolymerization using sulfamethazine as the template and o-phenylenediamine as the functional monomer on the modified electrode. Under optimal measurement conditions, electrochemical tests of different sulfamethazine concentrations (0.5 μM–200 μM) showed excellent linearity and a detection limit of 0.068 μM. In addition, the sensor demonstrated satisfactory selectivity, stability, and reusability. Furthermore, the sensor was applied to the spiked analysis of sulfamethazine in grouper aquaculture water, achieving recovery rates between 95.4% and 104.8%, with a relative standard deviation (RSD) of less than 4.14%. These results indicated that the developed method was effective for the analysis of sulfamethazine in aquaculture seawater, providing a new approach for the detection of antibiotic residues in seawater samples. Full article

Point-of-care (POC) antigen detection plays a crucial role in curbing the spread of viruses. Paper-based fluorescence aptasensors are expected to offer a low-cost tool to meet the needs of decentralized POC diagnosis. Herein, we report on a fluorescent paper-based sensing system for detecting the SARS-CoV-2 spike protein. The sensing system was constructed by loading multi-layer Nb₂C MXene nano-quenchers and carbon-dot-labeled aptamer (G-CDs@Apt) probes onto a mixed cellulose ester (MCE) paper substrate. On the Nb₂C MXene/G-CDs@Apt sensing paper, abundant G-CDs@Apt probes were attached to the multilayer MXene nano-quenchers and kept in a fluorescence-off state, while recognition of the target detached the G-CDs@Apt probes formed the nano--quenchers, resulting in fluorescence recovery of the sensing paper. The developed paper-based sensor performed well in the one-step detection of the SARS-CoV-2 S1 protein with a detection limit of 0.067 ng/mL (0.335 pg/test). The assay exhibited good selectivity and anti-interference in the detection of the SARS-CoV-2 S1 protein in artificial saliva. Moreover, the paper-based aptasensor was successfully used to detect the SARS-CoV-2 S1 protein in actual environmental samples with recoveries of 90.87–100.55% and relative standard deviations of 1.52–3.41%. The proposed technology provides a cost-effective alternative to traditional antibody test strips for a wide range of POC diagnostic applications. Full article

This study establishes and validates a novel ultra-high-performance liquid chromatography (UHPLC) method for the determination of urolithin A content in health products, a bioactive compound with potential anti-aging properties. Given the lack of standardized analytical methods for urolithin A in health products, this research addresses a critical gap in quality control. The method employs a methanol–water mobile phase, optimized gradient elution, and a specialized UPLC column (ACQUITY UPLC CSH Fluoro Phenyl) to achieve high resolution and specificity in the separation of urolithin A from its impurities. A variety of diluents, extraction solvents, and extraction times were tested to maximize analyte recovery and stability, with pure methanol yielding the highest recovery rate (over 95%) in 30 min. The method was validated in terms of linearity, sensitivity, repeatability, specificity, and precision. The calibration curve for urolithin A exhibited excellent linearity (r² = 0.9998) over a concentration range of 0.100–10.000 µg/mL. Detection and quantification limits were found to be 0.051 µg/mL and 0.103 µg/mL, respectively. Precision testing revealed an inter-operator RSD of 1.3%, and recovery rates for spiked samples consistently fell within the 98–102% range. The developed method was successfully applied to analyze the urolithin A content in a commercially available health product, demonstrating its practicality for routine quality control. However, this method may currently be affected by the excipient matrix. This research contributes to the establishment of robust, reliable, and high-sensitivity analytical methods for the bioactive compounds found in health products, with significant implications for regulatory compliance and consumer safety. Full article

A novel material composed of Au@SiO₂-(3-Aminopropyl Triethoxysilane) (Au@SiO₂-APTES) was successfully synthesised using the sol–gel method, and was used to modify glassy carbon electrodes. Its effectiveness as a molecular recognition element is evaluated in the design of an electrochemical sensor for the precise detection of dopamine. The Au@SiO₂-APTES composite was analysed using Fourier transform infrared spectroscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray diffraction. Elemental analysis verified the presence of oxygen, silicon, and gold, with atomic percentages of around 77.19%, 21.12%, and 1.65%, respectively. The corresponding elemental mapping for Au@SiO₂-APTES composite showed that the spatial distribution of all the elements was fairly homogeneous throughout the composite, indicating that the Au NPs are embedded in the silica structures. Traces of dopamine were detected by differential pulse voltammetry with a low limit of detection (S/N = 3) and quantification (S/N = 10) of 1.4 × 10⁻⁸ molL⁻¹ and 4.7 × 10⁻⁸ molL⁻¹, respectively. The Au@SiO₂-APTES composite had two linear ranges: from 4.7 × 10⁻⁸ to 1 × 10⁻⁷ molL⁻¹ and 1.25 × 10⁻⁷ to 8.75 × 10⁻⁷ molL⁻¹. Moreover, the sensor showed outstanding selectivity even in the presence of various potential interfering species. It also demonstrated good reusability and signal recovery when tested in human urine and plasma samples spiked with different dopamine concentrations. The electrochemical sensor, constructed using this novel composite material, shows great promise in the selective and sensitive detection of dopamine in the biological matrix. These results underscore the sensor’s capability for practical application in analysing real-world samples. Full article

Nitrite is a health and environmental hazard and pollutes water sources globally, but sensitive, rapid, and facile quantification methods are lacking. Herein, we report a method for extracting and quantifying low-concentration nitrite in surface water using minimal sample and solvent volumes. The nitrite reacted with sulfanilamide and N-1-naphthylethylenediammonium dichloride (NED), yielding an azo dye for extraction into an organic ion-associate liquid phase (IALP) formed in situ using ethylhexyloxypropylammonium and dodecyl sulfate ions. The addition of sodium acetate increased the pH, decreasing the cation charge from +2 to +1, improving extraction efficiency. Further, adding NaCl doubled the IALP volume, reduced the required standing time, and minimally affected absorbance, and adding concentrated HCl to the IALP enhanced the absorbance intensity via dye protonation. Crucially, the method achieved a 30-fold concentration factor compared to traditional pre-treatment methods, even without centrifugation, as well as a limit of detection of 0.09 µg NO₂-N/L. Spiked recovery tests with river and seawater samples (93–103%) matched those of established methods. Digital imaging of IALP-extracted lake water yielded a limit of detection of 0.4 µg NO₂-N/L. The method is a sensitive, efficient approach for nitrite detection, enabling rapid environmental monitoring via spectrophotometry and digital imaging. Full article