Microchimica Acta最新文献

The direct determination of glycopeptides and phosphopeptides in type 2 diabetes (T2D) samples is challenging due to their low abundance and the complexity of the sample matrix. To address this, we present a novel strategy by weaving organic linkers into a hydrogen-bonded organic framework (HOF), which is subsequently transformed into a metal-organic framework (MOF) via lanthanide ions (Ln³⁺). The resulting porous composite exhibits bifunctional properties, combining hydrophilic interaction liquid chromatography (HILIC) and immobilized metal ion affinity chromatography (IMAC), which enables the highly efficient simultaneous enrichment of glycopeptides and phosphopeptides directly from serum without extra pretreatment. The enrichment mechanism and possible binding modes were investigated by theoretical calculations. Based on this approach, 142 glycopeptides and 27 phosphopeptides were identified in serum from early-stage T2D patients and controls, respectively. This work successfully overcomes the hurdle of detecting low-abundance post-translational modification (PTMs) in complex clinical samples and opens new avenues for biomarker discovery in T2D through liquid biopsy.

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Carcinoembryonic antigen (CEA), a crucial non-specific tumor biomarker, exhibited a normal serum level of 2.5-5.0 ng/mL in healthy individuals. Elevations beyond this range signify increased tumor risk, underscoring the critical need for early biomarker detection. This study developed an inhibited electrochemiluminescence (ECL) aptasensor for ultrasensitive CEA detection, leveraging an Au-LDH-C₃N₄ composite as both the luminophore and sensing platform. The synthesis of Au-LDH- C₃N₄ involved the initial preparation of C₃N₄ by thermal pyrolysis of melamine, the subsequent in-situ growth of cobalt-iron layered double hydroxide (LDH) to form LDH-C₃N₄, and the final in-situ deposition of Au NPs. The resulting Au-LDH-C₃N₄ nanocomposite integrated the advantages of its components: the LDH-C₃N₄ heterojunction enhanced ECL stability and charge separation, oxygen vacancies promoted the generation of sulfate radicals (SO₄·⁻), and Au NPs improved electron transfer. Leveraging these synergistic effects, a label-free ECL sensing platform was constructed. The design of the nucleic acid probes using a complementary single-stranded DNA as a stable anchor and a specific aptamer for target recognition-ensured effective surface immobilization and high recognition specificity. The fabricated aptasensor achieved remarkable performance for CEA detection, featuring an extensive linear range (0.001 to 20 ng/mL) and an exceptionally low detection limit (0.3 pg/mL based on 3σ/S). In addition, the prepared aptasensor was successfully applied to serum analysis resulting in satisfactory results. This work presented the development of Au-LDH-C₃N₄-based ECL aptasensors and established an effective strategy for early detection of CEA.

Staphylococcus aureus (S. aureus) is a foodborne pathogen threatening public health due to the lack of rapid and sensitive detection methods for timely identification of its contamination. Surface-enhanced Raman scattering (SERS) shows great potential in quick bio-detection, but its pathogen detection analysis is challenged by limited size-matched substrates for both pathogen separation and SERS enhancement. Here, we designed an MXene-incorporated interconnected porous heterostructure (MIIPH) for effective capture and SERS detection of S. aureus. The MIIPH is fabricated through a one-pot hybridization process that incorporates single Ti₃C₂T_x MXene layers during the construction of the interconnected porous hydrogel. It enables S. aureus capture through both Ti-phosphate coordination and the boronic acid-diol binding interactions. Notably, owing to its highly uniform interconnected porous nanoarchitecture, MIIPH enhances the retention of S. aureus via a spatial confinement effect. Combined with a SERS-active silver probe (Ag-Apt), S. aureus is encapsulated within MIIPH and coated with Ag-Apt, enabling stable encapsulation of S. aureus within the interconnected porous network, while also providing synergistic SERS enhancement from both the embedded MXene component in MIIPH and silver plasma. This platform achieves S. aureus capture and determination with good sensitivity (a detection limit of 151 CFU/mL) and high specificity across a wide linear range (1.51 × 10³1.51 × 10⁸ CFU/mL). Furthermore, the method was successfully applied to the analysis of rice samples. Our approach not only provides a determination tool for S. aureus in complex matrices but also offers a versatile guideline for designing pathogen-specific SERS substrates.

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The limited sensitivity of conventional lateral flow assay (LFA) restricts its application in detecting trace targets. Although nanozyme-based LFAs could enhance detection performance significantly, they typically introduce additional steps, including the mixing and addition of the substrate for incubation, complicating the assay procedure. To circumvents this, we developed a hydrogel-integrated LFA platform (HG-LFA) by incorporating a sodium alginate (NaAlg) hydrogel network on a glass fiber membrane for encapsulating the chromogenic substrate 3,3’-diaminobenzidine (DAB). This three-dimensional network enables controllable release of DAB, automatically enhancing signal amplification with low background interference. Using SARS-CoV-2 E nucleic acid as a model target, the assay achieved a LOD of 0.146 nM, representing a 25-fold improvement over conventional Au@PtNPs-based LFA without signal amplification. After DAB catalysis, the signal enhancement of the HG-LFA that automatically releases the chromogenic substrate was comparable to that achieved by manual addition. In addition, the HG-LFA platform demonstrated high accuracy and stability in the detection of the target compound in biological matrix, offering a facile strategy well-suited for point-of-care testing (POCT) with high performance.

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Novel fluorescence-based molecularly imprinted polymer nanoparticles (MIP NPs) were prepared by incorporating fluorescent thionine within the polymer matrix. Thionine functioned both as a functional monomer and as an internal signaling probe, enabling a direct fluorescence readout without the need for external fluorescent labels. MIP NPs served as the selective recognition element for vancomycin (VA) assessment. VA bound to the selective cavities of the MIP NPs and quenched the fluorescence via static quenching mechanism. The fluorescence intensity decreased with increasing concentrations of VA. For MIP NPs-based fluorescence spectrometry development, 1 mg/mL MIP NPs dispersed in DI water completely interacted with the VA-containing sample. The assay exhibited a linear response ranging from 1.55 to 100 mg/L (LOD = 0.46 mg/L), enabling highly sensitive measurement of low VA levels in serum. The recovery was 97–115%, with within-run precision of 2.7–6.2%. Furthermore, the developed assay shows relatively high selectivity toward VA over other antibiotics/medications, including gentamicin, ampicillin, and acetaminophen. Spiked VA in the serum sample analyzed by MIP NP-based fluorescence spectrometry compared to the particle-enhanced turbidimetric inhibition immunoassay gave less than 12% relative error for all samples, suggesting acceptable accuracy of the proposed method. This assay achieved rapid results within 10 min in a one-shot approach, compared to the multi-step nanoMIP-based ELISA at 90 min. The high binding ability and selectivity of the thionine-based MIP NPs showed promise as a selective material against VA for other applications.

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In this study, N-CDs were combined with Eu³⁺ to construct a ratiometric fluorescence sensor (N-CDs@Eu³⁺) for the determination of tetracycline (TC). The nitrogen-doped carbon dots (N-CDs) with good water solubility, excellent fluorescence performance, and high stability successfully prepared by using the leaves of Mahonia fortunei leaf as the carbon source and ethylenediamine as the nitrogen source through a one-step thermal solvent method. In the presence of TC, the fluorescence intensity of N-CDs at 510 nm was quenched due to fluorescence resonance energy transfer (FRET), while the fluorescence intensity of Eu³⁺ at 616 nm was significantly enhanced through the antenna effect (AE). This ratiometric fluorescence sensor enables rapid, sensitive and highly selective detection of TC, with a detection limit as low as 7.5 nM. Moreover, a distinct color change from green to red can be observed under a 365 nm UV lamp. With the assistance of a smartphone sensing platform, visual semi-quantitative monitoring of TC was achieved. This method was successfully applied to the detection of TC in milk, pork, and honey, with recoveries ranging from 90.6% to 105.0%. This research demonstrates that this sensor holds potential application value in the field of real-time visualization detection and semi-quantitative determination of TC in biomedical and food safety sensing fields.

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A novel covalent organic polymer based on proflavine (COP-PF) is designed, synthetized and characterized to be used as a redox indicator in the biosensing field. COP-PF is introduced as an intrinsic redox indicator, ensuring reliable signal transduction without the need for external mediators. The platform was further reinforced with few-layer bismuthene, which is employed to structure gold screen-printed electrodes (AuSPE), improving electron transfer and DNA immobilization. Lastly, DNA nanoengineering is proposed in the shape of tetrahedral DNA nanostructures (TDNs) whose thiol-functionalized basal vertices enabled robust anchoring to FLB, while their apex carried a complementary probe to the analyte. The synergy of these materials yielded a highly robust biosensing system with exceptional sensitivity and selectivity. Biologically, the platform was applied to the detection of miRNA-27a, a clinically relevant biomarker of autism spectrum disorder (ASD), whose diagnosis has attracted the attention of the scientific community and society at large. The device achieved an ultralow detection limit of 10.3 aM, maintained high specificity in the presence of potential interferents, and demonstrated successful performance in spiked human serum samples. These results underscore the value of integrating emerging 2D nanomaterials, DNA nanotechnology, and functional organic polymers to advance medical diagnostics, offering a versatile route for nucleic acid biomarker detection in complex biological environments. Clinical trial number: not applicable.

An accurate method is presented for quantifying recombinant neuron-specific enolase (NSE) using isotope dilution liquid chromatography–mass spectrometry (IDMS) based on amino acid analysis. Traceable to the International System of Units − moles, the NSE concentration was determined as (0.0924 ± 0.0074) mg∙mL^− 1. The quantified NSE was then applied as a calibrator in a magnetic nanoparticle-based immunochromatographic assay (MNP-ICA) for point-of-care detection of NSE in human serum. Under the optimized parameters, the MNP-ICA exhibited a linear range from 2.5 ng∙mL^− 1 to 80.0 ng∙mL^− 1, with a detection limit of 2.09 ng∙mL^− 1. Intra- and inter-assay precision showed relative standard deviations below 4.5% and 11.6%, respectively, and recoveries ranged between 88.8% and 107.3%. Results from 16 actual human serum samples correlated well with a commercial ELISA kit. This agreement between the two immunoassays underscores the reliability of the MNP-ICA and confirms the immunoreactivity of the quantified NSE in clinical samples.

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A colorimetric/luminescent detection nanoprobe based on polyacrylic acid (PAA)-modified lanthanide-doped upconversion nanoparticles (PAA-UCNPs) and gold nanoparticles (AuNPs) is prepared for cysteamine detection. PAA-UCNPs (NaYF₄:Yb,Er@NaYF₄) exhibit green and red emission under near-infrared laser excitation. In the presence of cysteamine, citrate-stabilized AuNPs aggregate, causing a significant red shift in their absorption peak and weakening the red luminescence of PAA-UCNPs based on the inner filter effect (IFE). This nanoprobe enables rapid (5 min) and precise determination of cysteamine, with a wide linear range (0.1–1.0 µM in colorimetric mode and 0.25–1.25 µM in luminescence mode) and a low detection limit (44.4 nM in colorimetric mode and 23.3 nM in luminescence mode). Moreover, this dual-mode method is used for cysteamine detection in calf serum, demonstrating high sensitivity and reproducibility.

The successful low-temperature synthesis of Bi₂S₃ nanostructures via an in-situ solvothermal route employing the single-source precursor [Bi{S₂P(OC₃H₇)₂}₃] is reported. Harnessing this synthesis strategy, we engineered a pristine Bi₂S₃-based sensor platform that enables the simultaneous, multiplexed colorimetric detection of Co²⁺, Hg²⁺, and Cr³⁺ ions on unmodified hydrophobic substrates. This uniquely integrated sensor streamlines analytical workflows by eliminating extensive sample pre-treatment and specialized probes, simplifying field operation. The device exhibits remarkable detection limits,1 nM for Co²⁺, 10 nM for Hg²⁺, and 1000 nM for Cr³⁺ alongside high selectivity, operational stability, and repeatability. A regression-based machine learning algorithm was employed to process the optical response, enhancing the accuracy of heavy metal ion classification and quantification. The IoT-enabled architecture supports real-time, remote monitoring and validation studies in diverse water samples from Hyderabad, India, confirming platform robustness. This study positions single-source precursor-derived Bi₂S₃ nanostructures as a transformative solution for smart, decentralized water quality analysis, advancing progress toward universal access to safe water.