Microchimica Acta最新文献

A new type quartz crystal microbalance (QCM) sensor based on nitrogen sulphur co-doped carbon dots incorporated TiO₂ nanoparticles (NSCTi) nanocomposite and molecularly imprinting polymers (MIPs) is presented for acetamiprid (ACE) detection. After the preparation of NSCTi nanocomposite by using microwave irradiation treatment and the hydrothermal method, QCM chip modified NSCTi nanocomposite was developed by using the interaction between gold and sulphur. Then, MIPs based on QCM chip modified NSCTi nanocomposite was designed via the spin coating method providing mono-layered and homogeneous QCM surface in presence of methacryloylamidoglutamic acid (MAGA) as monomer and N, N′-azobisisobutyronitrile (AIBN) as initiator. After the characterization investigations, the linearity in the range 1.0 × 10^− 9 – 2.0 × 10^− 8 M with a detection limit (LOD) of 3.3 × 10^− 10 M was calculated for ACE. Finally, the developed QCM sensor was applied to wastewater samples with high recovery.

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Polyethyleneimine (PEI) modified 5,10,15,20-tetrakis(4-(hydroxyl)phenyl)porphyrin (THPP) assemblies with different morphologies are prepared via an evaporation-induced self-assembly method. The obtained THPP/PEI assemblies have positive surface potentials under physiological conditions. Therefore, THPP/PEI assemblies can capture extracellular vesicles (EVs) from MCF-7 cells via electrostatic interaction. Furthermore, THPP/PEI assemblies can also isolate EVs in size according to their different morphologies. The EV capture efficiency of THPP/PEI assembly is much high than those of inorganic ZnO-based nanowire arrays, although both rely on electrostatic attraction to capture EVs. Using the THPP/PEI assemblies, we demonstrated that the expression level of CD147 of EVs derived from the urine samples of colon cancer patients was 4.3-fold higher than that from the urine samples of healthy donors with a p-value less than 0.01. It is expected that the new THPP/PEI assemblies in this work has potential to be applied to liquid biopsy technology because of their portability and cost effectiveness.

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A dual-mode sensor based on intramolecular catalytic hairpin assembly strategy (intra-CHA) is proposed for Survivin mRNA detection. Intra-CHA, a triplex complex of tetraferrocene-labeled H1/H2, shortens H1-H2 distance and increases their local concentrations, accelerating reaction by 2.8-fold vs. free-CHA. Ruthenium-based covalent organic frameworks (RuCOFs) with Ru(dcbpy)₃²⁺ as luminophore has dual fluorescence-electrochemiluminescence (FL-ECL) properties. EDTA-incorporated RuCOFs@EDTA expands active sites, enhancing ECL efficiency 8-fold. Intra-CHA system is covalently conjugated to RuCOFs@EDTA through amide bond linkages. Target mRNA-triggered strand displacement reactions induce structural reconfiguration of the intra-CHA probes, resulting in controlled spatial segregation of tetraferrocene from the RuCOFs@EDTA interface. This results in the recovery of FL and ECL signals, enabling rapid and highly sensitive detection of Survivin mRNA. Experimental results show that the detection limits reach 0.04 fM (in the FL mode) and 0.009 fM (in the ECL mode) respectively, with excellent selectivity, stability, and reproducibility. The system has been successfully applied to detect Survivin mRNA in actual serum samples, providing a novel strategy for Survivin mRNA detection and paving the way for developing future diagnostic strategies for early cancer screening.

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Biomass-derived nitrogen self-doped carbon quantum dots (N-CQDs) were synthesized by the hydrothermal method using soybean residue as both nitrogen and carbon sources. The N-CQDs were applied to the study of cell multicolor imaging and temperature sensing in living cells. The experimental results show that N-CQDs have strong fluorescence intensity, good biocompatibility, good cell membrane penetration, good cell imaging performance and strong temperature sensitivity. In the temperature range 25 ~ 60℃, the intensity of the N-CQDs decreased with increase of temperature, and showed a good linear relationship. At 60℃, the relative fluorescence intensity was quenched by 65%. The results show that the soybean residue N-CQDs have high application potential and value in the field of fluorescence temperature sensing in living cells, and are of great significance for the development of nondestructive cell measurement nanothermometers. It is expected that the N-CQDs may establish as a temperature-sensitive fluorescence nanoprobe widely used in biomedical fields such as cell research.

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Alzheimer’s disease (AD) is a prevalent neurodegenerative disorder characterized by the pathological aggregation of amyloid-β (Aβ) protein. In this study, a plasmon-enhanced fluorescence (PEF) sensor based on Ag nanocubes (Agcubes) was developed for in situ imaging and tracking of Aβ₁₋₄₂ (Aβ₄₂) aggregation states. By precisely tuning the thickness of the silicon shell of the PEF sensor, the distance between rose bengals (RB) and Agcubes was optimized, leading to a remarkable 7.4-fold enhancement in fluorescence signal compared to RB. This sensor exhibited a significant “turn-on” response towards Aβ₄₂ aggregation, with an approximate 4.5-fold increase in fluorescence. Notably, the sensor could be successfully applied to detect and locate the process of Aβ₄₂ aggregation in living human neuroblastoma (SH-SY5Y) cells. Additionally, its staining sites were nearly identical to those of the commercial dye thioflavin T (ThT). This method enabled real-time in situ monitoring of intracellular Aβ₄₂ aggregation state, demonstrating great potential as a reliable diagnostic tool for AD.

An innovative organic-inorganic heterojunction based on meso-tetra(4-carboxyphenyl)-porphine (TCPP) and CsPbBr₃ perovskite is reported. Additionally, cobalt nitride (Co₄N) was employed as mimetic enzyme of lactic acid oxidase (LOX), thereby enabling sensitive detection of lactic acid in serum through photoelectrochemical (PEC) detection. The stability of CsPbBr₃ was significantly improved in aqueous solutions by substituting some of the long-chain ligands on its surface with TCPP, an organic semiconductor containing π-π bonds and carboxyl groups. Furthermore, the formation of a type-II heterojunction between TCPP and perovskite improved carrier separation and transport capabilities, resulting in more stable and enhanced photocurrent response. The non-enzymatic catalyst, Co₄N nanoparticles, demonstrate efficient catalytic activity toward lactic acid oxidation and enhance electron transfer to the heterojunction interface, thereby increasing the response current. The prepared PEC biosensor exhibits an effective sensing capability for lactic acid, with a working range of 0.2 mM to 10 mM and a detection limit of 0.03 mM. Furthermore, the biosensor features good selectivity and reproducibility, making it ideal for measuring lactic acid levels in human blood samples. This approach of forming heterojunctions by combining organic semiconductor materials with perovskites opens up new possibilities for constructing advanced perovskite-based photoelectric sensors.

Lateral flow assays (LFAs) have emerged as indispensable analytical platforms for rapid, portable, and cost-effective detection in clinical diagnostics, food safety assessment, and environmental monitoring. Despite their broad applicability, conventional LFAs exhibit intrinsic limitations in analytical sensitivity, which restrict their capacity to detect low-abundance biomarkers typically present during early pathological stages. These shortcomings arise from rapid capillary-driven flow, limited analyte–receptor interaction times, suboptimal binding kinetics, and insufficient signal generation, collectively increasing the likelihood of false-negative results. Enhancing sensitivity therefore requires systematic optimization of factors governing LFA performance, including the physicochemical properties, orientation of biorecognition elements, membrane composition with porosity, strip geometry, sample matrix interactions, label characteristics, and operational conditions. This review provides a comprehensive analysis of state-of-the-art strategies aimed at improving LFA sensitivity, encompassing nanoparticle and label engineering, chemical and enzymatic signal-amplification methodologies, advanced membrane and strip design, flow-rate modulation, sample pre-treatment and enrichment procedures, aptamer- and nanobody-based recognition systems, and multiplexing architectures. Additionally, emerging hybrid platforms that integrate microfluidics, engineered materials, or digital quantification demonstrate significant potential for approaching laboratory-level detection limits. While these innovations markedly advance LFA performance, challenges persist regarding cost, manufacturability, module integration, and preservation of user operability. This review delineates the translational pathway toward next-generation high-sensitivity LFAs for robust point-of-care (POC) diagnostics.

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Sensitive, enrichment-free detection of Listeria monocytogenes in food matrices is still challenging. Traditional lateral flow immunoassays (LFIA) come with limited sensitivity and often require lengthy pre-enrichment steps, which is a roadblock for rapid and on-site testing. In this work, a novel LFIA platform was developed that uses surface-modified polystyrene-gold nanoparticle composites (Ps-AuNPs) as enhanced colorimetric labels. The resulting signal enhancement enables the detection of L. monocytogenes without pre-enrichment steps. The assay also uses International Commission on Illumination Lab (CIELAB) color space-based image analysis pipeline to quantify colorimetric signals. CIELAB calculates perceptually uniform color differences (ΔE) and thus reduces subjective bias compared to conventional RGB analysis. The signal enhancement protocol resulted in an assay limit of detection (LOD) of 34 CFU/ml in PBS buffer and 452 CFU/ml in spiked romaine lettuce without any enrichment. The composite nanoparticle labels have excellent stability and retain performance over one month of ambient storage. The reported LFIA assay addresses the sensitivity gap in conventional systems and demonstrates practical applicability for rapid, cost-effective, and field-ready monitoring of L. monocytogenes contamination in real food samples.

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An ultra-sensitive impedimetric paper-based biosensor for the rapid detection of hepatitis C virus (HCV) core antigen in human serum, integrating double-noble Silver–AuNPs onto a carbon ink-patterned paper electrode is presented. The sensing interface is developed by immobilizing anti-HCV core antibodies onto a silver–gold nanoparticle (Ag–AuNP)-modified electrode surface, which serves as the biorecognition layer. This configuration enables label-free detection of antigen–antibody interactions using electrochemical impedance spectroscopy (EIS). Sensor performance was systematically optimized with respect to antigen concentration (0.1 ng/mL–500 µg/mL), incubation temperature, reaction time, and operational stability under repeated measurements. The optimized platform achieved a low limit of detection of 10.21 ng/mL and a limit of quantification of 34.05 ng/mL, with a wide linear dynamic range suitable for clinically relevant HCV core antigen levels. Analytical validation using HCV-positive clinical serum samples demonstrated high diagnostic accuracy and specificity against non-HCV samples. The proposed Silver–AuNPs based impedimetric immunosensor offers a low-cost, portable, and time-efficient alternative to conventional laboratory assays, with strong potential for point-of-care screening and large-scale surveillance of HCV infection, particularly in resource-limited settings.

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