Microchimica Acta最新文献

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.

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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