Microchimica Acta最新文献

A Mn-doped Fe₃O₄ (Mn-Fe₃O₄) nanozyme was synthesized using a one-step solvothermal method. Compared to pristine Fe₃O₄, Mn-Fe₃O₄ exhibits unique oxidase (OXD)-like activity and enhanced peroxidase (POD)-like activity. The superior catalytic performance arises from the incorporated Mn species and the associated oxygen vacancies facilitate oxygen adsorption and activation, establishing an efficient self-cascade catalytic system. In this system, hydrogen peroxide (H₂O₂) generated in-situ through OXD-like catalysis can trigger mimic-POD reactions. A dual-mode antioxidant detection platform was subsequently constructed using melatonin (MT) as a proof of concept, with 3,3',5,5'-tetramethylbenzidine (TMB) serving as the substrate for the Mn-Fe₃O₄ nanozyme. The colorimetric mode enables rapid visual screening by monitoring the oxidation of TMB to a blue-colored product, achieving a detection limit of 0.13 µM. The electrochemical mode features the novel utilization of mesoporous silica nanochannels for the selective enrichment of oxidized TMB (oxTMB), enabling highly sensitive quantification of MT with a detection limit as low as 0.6 nM. The assay applied to commercial tablets shows excellent recovery and reproducibility. This work combines engineered nanozymes with nanofilm-modified electrodes, offering an innovative approach for constructing advanced multimodal sensing systems.

Early cancer diagnosis is vital for improving patient survival. The present work uses a novel and label-free baseline calibrated electrochemical immunosensor for the sensitive detection of carcinoembryonic antigen (CEA). The sensor platform was constructed on a glassy carbon electrode (GCE) modified with electro-synthesized silver nanoparticles (e-AgNPs) and carboxyl-functionalized NiFe₂O₄ nanoparticles (cit-NFO-COOH). This nanocomposite enhanced the electrode surface area, conductivity, and antibody immobilization stability. Comprehensive material characterization was performed using Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM), energy dispersive X-ray (EDX), X-Ray diffraction analysis (XRD), and dynamic light scattering (DLS), and zeta potential analysis, while electrochemical performance was evaluated via cyclic and differential pulse voltammetry. Optimization studies disclosed that the optimal concentrations for AgNO₃, cit-NFO-COOH, and antibody were 0.05 mM, 1000 mg/L, and 20 µg/mL, respectively. The fabricated immunosensor exhibited a wide linear detection range (0.1 pg/mL to 10 ng/mL) with a linear regression equation of y = 0.2306ln [CEA] + 3.0227 (R² = 0.999) and an exceptionally low detection limit of 0.09 pg/mL. The precision and accuracy of the probe for intraday and interday tests were assessed as mean relative standard deviation (RSD%) and relative error (RE%) with values of 4.1%, 3.0%, 10.2%, and 10.9%, respectively. Also, specificity was tested in the presence of various biologically available biomarkers and biomolecules with absolute mean change of 8.2%. The validation results were confirmed following the Food and Drug Administration (FDA) guidelines for developing sensing platforms in biological media. The high sensitivity and stability of this biosensor highlight its significant potential as a powerful tool for clinical application in cancer biomarker monitoring.

We developed a dual-functional fluorescent probe based on cerium-doped carbon dots (Ce-CDs). The Ce-CDs were synthesized via a facile hydrothermal route using trimesic acid, L-lysine, and cerium nitrate as precursors, serving to quantify both tetracycline (TET) and carmine (CM). The Ce-CDs show excellent excitation-independent fluorescence, with optimal excitation at 340 nm, emission at 410 nm, and quantum yield of 17.4%. Due to the inner filter effect and static quenching, their fluorescence intensity decreased linearly with increasing TET/CM concentration, enabling a new fluorescent probe. The developed sensing platform exhibited a wide linear response (0.125-50.0 µM) and high sensitivity, with limits of detection of 0.037 µM for TET and 0.035 µM for CM. The method's accuracy and precision were rigorously evaluated in complex food samples. Recoveries for TET in a variety of meats (pork, pork liver, beef, chicken) fell between 94.4% and 113%, and for CM in foodstuffs (dried strawberries, bayberry juice, red bull drink) fell between 92.0% and 115%, with relative standard deviations ≤ 5.8%. Thus, Ce-CDs are excellent probes for food TET and CM detection.

Hepatocellular carcinoma (HCC) is one of the most lethal malignancies worldwide, and early diagnosis is crucial. Golgi protein 73 (GP73) has emerged as a promising serum biomarker for HCC. However, current detection methods often fail to meet routine screening requirements due to limitations in sensitivity and operational simplicity. To address these challenges, we have developed a novel fluorescent aptamer-based sensor for highly sensitive GP73 detection based on the fluorescence resonance energy transfer (FRET) mechanism between graphitic carbon nitride quantum dots (g-CNQDs) and a copper-based metal-organic framework (Cu-TCPP). g-CNQDs were covalently conjugated with a GP73-specific aptamer to serve as the fluorescent donor, while two-dimensional Cu-TCPP nanosheets acted as the efficient acceptors. Fluorescence was quenched upon donor-acceptor interaction via FRET. In the presence of GP73, aptamer-target binding disrupted FRET interaction, separating the donor from the acceptor and restoring fluorescence in a concentration-dependent manner. Under optimal conditions, the sensor exhibited excellent linearity over a concentration range 1.0-225.0 ng mL⁻¹, with a detection limit as low as 0.907 ng mL⁻¹. Recoveries for spiked human serum samples ranged from 95.96% to 103.85%, with relative standard deviations (RSDs) of 0.38%-5.48%. The developed aptamer sensor demonstrated excellent sensitivity, selectivity, and stability, providing a powerful tool for early HCC diagnosis and offering strong potential for real-time analytical applications.