Quantitative analysis of cyclosporine A in whole blood samples of liver transplant recipients using a stir bar-assisted magnetic dispersive solid phase extraction combined with HPLC-MS/MS.

This study developed a novel streptomycin immunodetection method based on the Amplified Luminescence Proximity Homogeneous Assay (AlphaLICA), termed STR-AlphaLICA, for the highly sensitive and rapid detection of streptomycin residues in infant formula. The method was established by conjugating streptomycin-bovine serum albumin (STR-BSA) to receptor microspheres and goat anti-mouse IgG antibody to donor microspheres, leveraging the principle of competitive binding between free streptomycin and the immobilized STR-BSA for specific monoclonal antibodies. In the homogeneous system, fluorescence signals are generated through singlet oxygen energy transfer upon 680 nm laser excitation, allowing direct detection without washing steps. The established standard curve demonstrated excellent linearity (r = 0.99977) within the range of 0.1-312.5 ng mL-1, with a detection limit (LOD) of 0.169 ng mL-1 and a quantification limit (LOQ) of 0.776 ng mL-1. Validation results showed excellent intra- and inter-batch precision (CV < 5.02%) and spiked recovery rates ranging from 91.21% to 106.64%. Cross-reactivity with the structural analog dihydrostreptomycin was 69.87%, while responses to other common antibiotics remained below 0.05%, indicating high specificity. Furthermore, validation results in five complex matrices-including honey and shrimp meat-further demonstrate the method's excellent universality and reliability. In actual sample testing, the results showed significant correlation (r2 = 0.9414) when compared with commercial ELISA kits, confirming the method's suitability for high-throughput screening and precise quantification of streptomycin residues in complex matrices such as infant formula. This provides new technical support for food safety monitoring.

Benvitimod is a non-steroidal tyrosine protein kinase inhibitor commonly used to treat psoriasis. However, it can cause adverse reactions such as contact dermatitis and itching, which can seriously impact consumer health. This study involved designing and synthesising a novel fluorescent labeling reagent, 2-((7-nitrobenzo[c][1,2,5]oxadiazol-4-yl)oxy)benzoic acid (NBD-SA). This reagent is used to detect benvidimod in cosmetics using high-performance liquid chromatography with fluorescence. With the help of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride/4-dimethylaminopyridine catalysts, NBD-SA can react at 45 °C within an hour, thus providing a quick and effective labeling method for benvitimod. The resulting derivative exhibits remarkable stability and fluorescence properties. The maximum excitation wavelength is 461.96 nm, and the emission wavelength is 578.97 nm. Four cosmetic formulations were completely separated by using a CAPCELL PAK C18 column and gradient elution. Under the optimum conditions, the standard curve shows a good linearity with a determination coefficient of r2 = 0.9999. The LOD and LOQ were 0.04 ng mL-1 and 0.11 ng mL-1, respectively. Thus, NBD-SA was successfully used to detect benvitimod that had been illegally added to cosmetics.

The early diagnosis and postoperative monitoring of ovarian cancer rely significantly on the sensitive detection of antigen CA12-5. In this work, a photoelectrochemical immunosensor was developed for the detection of CA12-5, utilizing a CdS/SrTiO3 heterojunction as the photoactive matrix and NiCo2O4 as a quencher probe. The Z-type heterojunction promotes the separation of photogenerated electrons and holes, suppresses the recombination of charge carriers, and thereby significantly enhances the initial photocurrent response. Furthermore, the introduced NiCo2O4 quencher generates steric hindrance and competes effectively with the photosensitive material for light absorption, leading to a reduction in the photocurrent signal. This quenching effect greatly enhances the detection sensitivity for CA12-5. The fabricated immunosensor exhibited excellent selectivity and stability under optimal conditions, achieving a wide linear detection range from 5 pg mL-1 to 50 ng mL-1 and a low detection limit of 1.3 pg mL-1.

Photochemical vapor generation (PVG) is an attractive yet under-exploited sample-introduction strategy for atomic spectrometry. There remain challenges in improving the efficiency of PVG of elements and expanding the range of PVG applications. Here, these issues have been tackled by introducing a metal-free porphyrinic covalent organic framework (SU-3), cross-linked by robust polyimide bonds and exhibiting strong ultraviolet light absorption and photocatalytic activity. Liquid-phase exfoliation converts the bulk framework into ultrathin SU-3 nanosheets (SU-3 CONs), further amplifying its photocatalytic capacity. Both SU-3 COF and SU-3 CONs were harnessed as photocatalysts to boost PVG of rhenium (Re) prior to inductively coupled plasma mass spectrometry (ICP-MS), yielding 27-fold and 71-fold signal enhancements, respectively. Compared to bulk COF, the superior performance of nanosheets stems from their more exposed catalytic sites and amplified photocatalytic activity. The method minimizes low-molecular-weight acid consumption, precludes extraneous transition-metal sensitizers, and affords linearity from 0.05 to 100 ng mL-1 with a 0.7 ng L-1 limit of detection─superior to that of traditional PVG methods sensitized by transition metal ions. Accurate Re quantification in river, lake, and tap water samples confirms the robustness and practicality of the method. This work thus establishes metal-free COF nanosheets as a versatile platform for advancing photochemical vapor generation, opening new avenues for ultrasensitive elemental analysis.

Carbendazim (CBZ) poses significant health risks, necessitating its selective and sensitive detection. Herein, we report a complementary strand (cDNA)-free ratiometric aptasensor based on persistent luminescence nanoparticles (PLNP) that operates without in-situ excitation for the accurate quantification of trace CBZ in complex matrices. The sensor integrates an aptamer to enhance affinity and specificity, yet eliminates the conventional quencher-labelled cDNA. Methylene blue (MB) is innovatively introduced as a multifunctional substitute: it self-adsorbs onto the aptamer-modified PLNP through π-π stacking, electrostatic attraction, and hydrogen bonding, serving simultaneously as the resonance-energy-transfer acceptor and the second signaling channel. MB quenches the PLNP phosphorescence at 542 nm while generating its own 700 nm emission. Upon CBZ addition, CBZ-aptamer binding releases MB, disrupts the energy-transfer pathway and switches the 542 nm signal "on" while turning the 700 nm signal "off". This anti-directional dual-channel read-out efficiently eliminates background fluorescence and external interference, enhancing sensitivity. The sensor exhibits a wide linear range of 2.27-500 ng mL-1, a detection limit of 0.682 ng mL-1, and quantitative recovery (90.1-107.4%). The proposed strategy offers superior selectivity, sensitivity, and accuracy. The developed sensor was validated by analyzing a certified reference materials and comparing with an HPLC method and successfully applied to the determination of CBZ in real food samples (cherry tomatoes, oranges, lettuce, green peppers, strawberries, cucumbers, apples, and Chinese chives).

Metal-organic framework MIL-101(Cr) functionalized β-cyclodextrin-modified magnetic multi-walled carbon nanotubes for efficient extraction of amphenicol antibiotics.

In this work, a fluorescent aptasensor was constructed for enrofloxacin (ENR) detection by combining the polyvalent aptamer (PA) structure, apurinic/apyrimidinic endonuclease 1 (APE1)-mediated signal amplification and mesoporous silica-encapsulated perovskite quantum dot (CsPbBr3@MSN) nanocomposites. With their multiple recognition sites, polyvalent aptamers bonded to ENR and released the trigger for the strand displacement reaction. Meanwhile, a highly sensitive FRET-based sensor was constructed using the CsPbBr3@MSN probe and gold nanoparticles (Au NPs). In the presence of the trigger and APE1, the fluorescence was recovered by separating the CsPbBr3@MSN probe and Au NPs via a cyclic strand displacement reaction. Coupled with the signal amplification strategy, this system achieved the linear detection of ENR in the range of 0.1 pg mL-1 to 50 ng mL-1 with a detection limit of 0.073 pg mL-1. This sensor offers a novel analytical strategy for detecting antibiotic residues and holds significant potential for applications in food safety monitoring and environmental analysis.

Hormone residues, especially in aquatic products, have become a serious threat to food safety. The development of sensitive, affordable, on-site, and quick detection methods for hormone residues still faces great challenges. Herein, taking methyltestosterone (MT) as a representative analyte, a competitive lateral flow immunoassay (LFIA) platform was constructed using ultrabright lanthanide-doped luminescent nanoparticles, i.e. YVO4:Eu, as the label probe. The YVO4:Eu NPs were obtained by a facile hydrothermal method using lanthanide ions and sodium orthovanadate as the precursors and polyacrylic acid as the surface modifier. Owing to the advantages of high fluorescence quantum yield, abundant surface functional groups, good dispersity and good water solubility, the harvested YVO4:Eu NPs are a competitive and promising label probe in LFIA. The YVO4:Eu LFIA test strips showed a detection limit, i.e. 0.1 ng mL-1, which was about 1 to 2 orders of magnitude lower than that of most reported methods. Furthermore, the proposed test strips were successfully applied for the quantitative, accurate, and quick screening of MT in fish samples. This work reports a competitive luminescent label probe for food safety and quality control.

Zearalenone (ZEA), an environmental mycotoxin produced by Fusarium fungi, is widely present in grains and grain products. Due to its potent carcinogenicity and toxicity, it poses a serious threat to human and animal health, necessitating the development of simple, sensitive, and reliable ZEA detection methods. This study constructed a novel electrochemiluminescence (ECL) probe based on Cu2O@Au. This probe synergistically interacts with luminol, utilizing enzyme-catalyzed glucose decomposition to generate H2O2, which is further catalyzed to hydroxyl radicals (OH˙), thereby significantly amplifying the ECL signal. To enhance catalytic efficiency, a Tb-Cu metal-organic framework (Tb-Cu MOF) with horseradish peroxidase-mimetic activity was integrated onto the sensor interface to accelerate hydrogen peroxide decomposition. This integrated sensing platform achieves highly sensitive detection of ZEA, with a detection limit as low as 0.017 pg mL-1 and a linear range spanning 0.10 pg mL-1 to 100 ng mL-1. This strategy provides a powerful analytical tool for detecting trace toxins in complex biological matrices, demonstrating broad application prospects in fields such as food safety and environmental analysis.

The sour cherry (Prunus cerasus L.) is an important fruit species in Eastern Europe due to its multiple uses. The aim of this study was to evaluate the ripening-stage-dependent compositional changes in some Hungarian-bred sour cherry varieties ("amarelle" type 'Korai pipacs', "morello" types 'Érdi bőtermő' and 'Újfehértói fürtös'), with a special view on biologically active compounds (anthocyanins, polyphenols, vitamin C, melatonin), organic acids, sugars, and antioxidant characteristics. The measured soluble solid content varied within a narrower range than reported in the literature, whereas the total acid content and soluble solid content were consistent with previous data. As the analyses were based on samples from a single year (2022), potential year-to-year variability should be considered when interpreting the results. The "morello" type varieties reached a higher amount of different sugar compounds than the "amarelle" type variety. Among the examined organic acid compounds, malic acid was detected in the highest quantity (176.75 to 669.44 mg 100 mL-1). The vitamin C data (5.74 to 13.46 mg 100 mL-1) had similarity to the literature data. The "amarelle" type 'Korai pipacs' reached the highest antioxidant content (131.11 mM AS L-1) in the third picking time. Among the naturally occurring pigments the "morello" type, straining sour cherries reached a higher amount (113.71 µg mL-1 in 'Érdi bőtermő' and 59.4 µg mL-1 in 'Újfehértói fürtös' of cyanidin glucosides), than the observed "amarelle" type (23.42 µg mL-1 in 'Korai pipacs' of cyanidin glucosides). Melatonin was detected in all examined varieties (1.56 to 13.25 ng mL-1).

The therapeutic bioanalytical challenge activity of tyrosine kinase inhibitors (TKIs) can be assessed by measuring them in biological samples such as plasma and serum. Determining these compounds requires an efficient sample before the analysis to minimize matrix effects and enhance preconcentration. This study presents the use of a composite of layered double hydroxide (LDH) and metal organic framework (MOF) composite for extracting and preconcentrating of sunitinib, imatinib, and dasatinib. The proposed composite was synthesized through the in-situ growth of MIL-101(Cr)-NO2 MOF on the MgFe-LDH surface. The extraction process involves adding 5 mg of LDH/MIL-101(Cr)-NO2 to the plasma solution containing the analytes, under nitrogen blowing. Centrifugation separated the analyte-loaded sorbent, which was then eluted with 125 μL of mobile phase. The organic phase was used subsequent high performance liquid chromatography (HPLC) - photo diode array detector (PDA) analysis. Under optimum conditions, the developed method demonstrates favorable extraction recoveries (66-74%), low limits of detection (LOD) and quantification (LOQ) (0.46-0.69 ng mL-1 and 1.5-2.2 ng mL-1, respectively), wide linear ranges (LRs) (1.5-200 ng mL-1) with high coefficients of determination (0.997-0.999) and proper repeatability (RSD ≤ 6.6%). Notably, the method provides the use of minimal amounts of sorbent and solvents, short extraction time, no need for complicated instruments, and high performance in monitoring anti-cancer drugs in biological samples.

This study successfully synthesized Fe3O4@Au, Fe3O4@Se, and Fe3O4@MnO2 nanostructures with inherent oxidation properties of Fe3O4 nanoparticles. These nanostructures exhibited plasmonic properties, facilitating visible light absorption and spectral overlap with quantum dots fluorescent microspheres (QD-FMs) for quenching QD-FMs via an inner filter effect. Based on the composite nanostructures, we developed dual-mode (colorimetric, CM, "turn off" mode; fluorescence quenching, FQ, "turn on" model) LFIA platforms. Among them, the Fe3O4@Au-based FQ-LFIA demonstrated superior sensitivity for albendazole (ABZ) which is a veterinary with a detection limit of 0.072 ng mL-1, 69.4-fold lower than Fe3O4@Au-CM-LFIA (5 ng mL-1). The result is attributed to the high molar extinction coefficient (8.877 × 1011 M-1 cm-1), strong quenching efficiency (η = 92.2%), and high quenching constants (Kn = 67.236) of Fe3O4@Au. The assay also demonstrated satisfactory recovery (80.4-108.6%) and precision (CV < 13%) for the detection of ABZ in actual samples. The developed Fe3O4@Au-FQ-LFIA is effective for detecting ABZ in agri-food products.

A simple, rapid, sensitive, and reliable spectrofluorimetric approach has been developed for the analysis of delafloxacin (DEL) in human plasma. The proposed method is based on the formation of a micellar fluorescent complex through the interaction of DEL with 2% sodium dodecyl sulfate (SDS) using a phosphate buffer (pH 4.2), producing a pronounced emission at 470nm upon excitation at 380nm. The experimental conditions that affected the one-pot synthesis were investigated and optimized. The calibration curve exhibited a linear relationship over a concentration range of 2.0-120.0 ng mL-1, with detection (LOD) and quantitation limits (LOQ) 0.6 and 1.9 ng mL-1, respectively. The designed approach was validated following the ICH and FDA guidelines, producing a precise analysis of DEL in its tablets and plasma samples with high recovery percentage. The results provide that the method possesses excellent eco-friendly properties, highlighting its strong compatibility with the principles of green chemistry.

Frugivorous animals routinely ingest fruit sugars and the associated products of microbial fermentation. Yeast-derived ethanol within fruit is a recently described chronic feature (approx. 14 g d-1) of the chimpanzee diet, but physiological evidence of exposure has not yet been demonstrated. We assayed urine collected from 19 wild chimpanzees for the presence of ethyl glucuronide (EtG), a direct metabolite of ethanol. Urine samples were obtained from study individuals feeding almost exclusively in the canopy of mast-fruiting Gambeya albida (=Chrysophyllum albidum), freshly fallen fruits of which averaged a pulp-ethanol content of 0.09% (±0.01 s.e.; range 0.01-0.40%) across multiple ripe crops. Of 20 individual urine samples (nine from females and 11 from males, aged 10-46 years), 17 tested positive for EtG at an analytical threshold of 300 ng ml-1; out of a subset of 11 of these positive samples, 10 samples further tested positive at a threshold of 500 ng ml-1. These values are high relative to calibrations of the test method for modern humans and are consistent with substantial rates of ethanol consumption via frugivory in the wild.

Tobacco smoke exposure not only increases the risks of lung cancer and cardiovascular disease, but can be a stressor contributing to mental illness. It is important to clarify the relationship between chronic tobacco smoke exposure and mental stress from the perspective of disease prevention. We developed a simple and highly sensitive method for simultaneously analyzing nine biomarkers: nicotine and cotinine (tobacco smoke exposure markers); cortisol, testosterone, and dehydroepiandrosterone (stress-related markers); and serotonin, melatonin, dopamine, and oxytocin (relaxation-related markers). Biomarkers were extracted and concentrated by in-tube solid-phase microextraction with a Supel-Q PLOT capillary, followed by separation and detection within 7 min using liquid chromatography-tandem mass spectrometry on a Discovery HS F5 column. Calibration curves using stable isotope-labeled internal standards showed good linearity (0.005-100 ng mL-1) with detection limits of 0.09-13.5 pg mL-1. Intra-day and inter-day precision had relative standard deviations below 7.2% and 15.5% (n = 6), respectively, with recovery rates of 84.0-108.8%. The automated method requires only ultrafiltration of hair methanol extract, enabling non-invasive pg-level analysis using just a few milligrams of hair. Hair analysis reflects an association between chronic tobacco smoke exposure and stress. This method is effective for analyzing the relationship between long-term tobacco smoke exposure and chronic stress.

This study presents a ZnO/CdIn2S4 (ZnO/CIS) heterojunction-based photoelectrochemical immunosensor for sensitive prostate-specific antigen (PSA) detection. The separation and directional transport of photogenerated charge carriers are enhanced by the built-in electric field at the heterojunction interface, resulting in an increased initial photocurrent. Following immunocomplex formation, alkaline phosphatase-catalyzed ascorbic acid serves as an electron donor to quench photogenerated holes for signal amplification. Density functional theory (DFT) calculations and systematic electrochemical characterizations verify the critical role of the built-in electric field in enhancing charge separation and transfer. The sensor exhibited a wide linear range of 0.02-60 ng mL-1, a low detection limit of 15.80 pg mL-1, and great reproducibility and stability. This study provides mechanistic insights into heterojunction-assisted photoelectrochemical (PEC) sensing, establishing a practical strategy for high-performance clinical biosensors. The approach demonstrates scalability toward multifunctional PEC platforms for broader biomarker detection and comprehensive diagnostics.

Conventional lateral flow immunoassays (LFIAs), which rely on visual interpretation for qualitative analysis, are confronted with limitations such as susceptibility to environmental interference, insufficient sensitivity, and a restricted detection range, thereby hindering its capacity to meet the growing demands of modern point-of-care diagnostics. To address this limitation, the photothermal effect, which converts analyte concentration into quantifiable temperature changes, provides LFIA platforms with enhanced sensitivity and stability. Herein, combining an optical microfiber Mach-Zehnder interferometer (mMZI) with conventional gold nanoparticle (Au NP)-based LFIA strips, a more sensitive photothermal platform (mMZI-LFIA) was engineered for quantitative measurement on LFIA. The proposed mMZI, encapsulated by the high thermo-optical coefficient polymer, exhibits excellent thermal sensitivity, enabling it to capture minute temperature variations due to localized heating generated by the Au NPs via the localized surface plasmon resonance effect. As a proof-of-concept, we employed a sandwich format LFIA for the detection of prostate-specific antigen, used as the model system. The results show high sensitivity with a detection limit (LOD) of 0.347 ng mL-1, which was around 11.5 times more sensitive than traditional colorimetric LFIA based on Au NPs. Meanwhile, the mMZI-LFIA broadened the detection range to 0.5-256 ng mL-1. Furthermore, to further verify the applicability of the proposed biosensor, quantitative analysis of the competitive Cr3+ test strips (0.195-50 ng mL-1) also achieved LOD (0.235 ng mL-1) improvement. In this work, the integration of optical microfibers with commercially available LFIA strips has enabled photothermal quantification in conventional LFIA without requiring additional thermal measurement equipment, significantly enhancing detection sensitivity, accuracy, and reliability, thereby offering a promising new pathway toward the development of portable photothermal LFIA systems.

Increasing environmental pollution and climate change intensify the occurrence of harmful cyanobacterial blooms. These blooms release cyanotoxins, such as cylindrospermopsin (CYN), a hepatotoxic compound that threatens freshwater ecosystems, ecological stability, and human health. Addressing this challenge requires effective monitoring strategies aligned with the United Nations Sustainable Development Goal 6 (Clean Water and Sanitation). In this study, pencil graphite electrode (PGE) and conductive polymer based electrochemical aptasensor systems were developed for the selective and sensitive detection of CYN in both laboratory (deionized water) and environmental (lake water) samples. The proposed sensors provide low-cost, rapid, and reliable analytical platforms for environmental monitoring and sustainable water management. Poly(3,4-ethylenedioxythiophene) (PEDOT), and polypyrrole (PPy) were electropolymerized onto PGEs to enhance conductivity and provide effective CYN-specific aptamer (cynApt) immobilization. The surface morphologies and elemental compositions of bare PGE, PGE/PEDOT, and PGE/PPy were characterized by scanning electron microscopy/energy-dispersive X-ray spectroscopy (SEM/EDX), while their electrochemical properties were systematically evaluated using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Functional groups formed after polymer deposition and subsequent aptamer immobilization were analyzed using Fourier transform infrared (FT-IR) spectroscopy. The first system, PGE/PEDOT/cynApt, achieved detection limits of 0.23 ± 0.005 ng mL-1 (0.55 ± 0.013 nM) and 0.27 ± 0.008 ng mL-1 (0.65 ± 0.018 nM) for CYN in deionized and lake water, respectively, using CV. The second system, PGE/PPy/cynApt, exhibited superior performance, reaching detection limits of 0.18 ± 0.005 ng mL-1 (0.43 ± 0.012 nM) in deionized water and 0.24 ± 0.009 ng mL-1 (0.58 ± 0.022 nM) in lake water, respectively, using EIS. Conductive polymer modifications, with PEDOT and PPy, significantly enhanced the analytical response. Both platforms exhibited high selectivity toward CYN over other environmentally relevant cyanobacterial toxins, including okadaic acid (OA), saxitoxin (STX), and anatoxin-a (ATX-a), which are known to co-occur with CYN in freshwater blooms. In addition, the developed aptasensors retained their functional performance over a 7-day storage period, indicating suitable stability for practical use. This practical approach for the early detection of CYN in aquatic environments contributes to the prevention of water-related health risks and supports sustainable agricultural practices.

A novel electrochemical immunosensor based on MXene-Au and Au-Ce-COF was constructed and applied for the ultra-sensitive detection of methyl parathion (PTM). The MXene-Au nanomaterials were obtained by acid etching the precursor to obtain layered MXene, and then generating gold nanoparticles (Au NPs) in situ on the MXene surface. A Au-Ce-COF was synthesized by first synthesizing a Ce-COF through simple stirring under nitrogen (N2), and then Au NPs were generated by reducing HAuCl4 (chloroauric acid); finally, the material was ultrasonically synthesized to form the final product. The materials were characterized by multiple techniques with their electrochemical properties evaluated via cyclic voltammetry (CV). Electrochemical test results indicate that the fabricated sensor demonstrates outstanding electrocatalytic performance for PTM detection. In addition, the constructed sensor shows an extended linear response range (0.00475-9.5 μg mL-1), lower limit of detection (1.58 ng mL-1), and promising application in practical assays.