Microchimica Acta最新文献

Autoantibodies play a critical role in predicting diseases and monitoring therapeutic outcomes. Limitations of current autoantibody detection techniques include prolonged detection times and operational complexity. This study aims to develop a bidirectional microfluidic platform for the detection of autoantibodies. A “double inlet” and “waste outlet” structure was developed on the bidirectional lateral-flow microfluidic chip (BiLFMC). Using anti-citrullinated peptide antibodies (ACPA) as a model, this study validated the feasibility and performance advantages of the BiLFMC in the diagnosis of autoimmune disease. The BiLFMC was optimized by selecting the optimal distances between the sample inlet and waste outlet, as well as the ideal diameter for the waste outlet. The most suitable absorbent material was chosen for the waste absorbent pad. The detection and anti-interference performance of the unidirectional mode, unidirectional sequential mode, and bidirectional mode were compared, demonstrating that the bidirectional microfluidic chip significantly enhanced anti-interference capabilities. For ACPA detection, a serum sample required only a 1:100 dilution and 10 μL volume, with results available in 8 min. The coefficient of variation (CV) for repeatability ranged from 7.04% to 13.55%, while the CV for intermediate precision ranged from 11.06% to 14.49%. The limit of quantitation was 3.951 RU/mL, and the upper limit of the linear range was 500 RU/mL. When compared to ELISA results, the consistency coefficient was 0.8302. Furthermore, the BiLFMC was able to accurately distinguish samples exceeding the ELISA upper limit (> 196 RU/mL). A bidirectional microfluidic chip has been developed, incorporating indirect detection methods to enhance the anti-interference capability of the microfluidic platform.

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Enzyme biosensors used in continuous monitoring applications rely on amperometry as redout, which continuously draws energy, introduces ohmic drops and requires a reasonably reliable reference electrode. To help address these challenges a new experimental “zero-current” chronopotentiometry readout for wired glucose biosensors is introduced. The method records the transition time needed to chemically reduce the wired redox probe at the electrode by the enzymatically catalyzed turnover of glucose. After an electrochemical oxidation step, the open circuit potential changes over time because the enzymatic turnover continuously reduces the redox probe, thereby altering the ratio of reduced to oxidized form at the electrode. The exhaustion of the oxidized probe is indicated by an inflection of the potential at a specific transition time. The inverse value of the transition time is found to be proportional to glucose concentration, consistent with mass transport-limited kinetics across the diffusion limiting membrane and serves as sensor signal. For this reason, the specific potential value is not important for the measurement, allowing one to employ less accurate reference electrodes. Lower glucose concentrations result in longer transition times, resulting in a method that successfully covers the entire physiological concentration range.

An innovative multiplex molecular detection method is introduced, ingeniously combining solid-phase PCR with liquid-phase PCR through the assistance of magnetic fluorescent-coded microspheres. In the amplification system, the liquid-phase PCR continuously generates target DNA fragments. Using these target DNA fragments as templates, specific primers on corresponding magnetic fluorescent-coded microspheres simultaneously perform solid-phase PCR. To comprehensively assess the performance of this multiplex nucleic acid detection method, we selected the quantitative detection of eight high-risk human papillomavirus (HPV) types (16, 18, 31, 33, 45, 56, 58, and 59) as a specific case for systematic investigation. This method demonstrated exceptional sensitivity, with a broad dynamic detection range from 6 × 10¹ to 6 × 10⁶ copies/µL with R² > 0.99. The limits of detection for this method were lower than 55 copies/µL, with the majority even below 40 copies/µL. Importantly, the developed method exhibited superior selectivity, wherein the amplified signal was detectable exclusively in the presence of the target nucleic acid. The consistency analysis revealed a strong correlation between the solid-liquid biphasic multiplex PCR assay and conventional qPCR, with correlation coefficients exceeding 0.99 in most cases. Additionally, detecting cervical exfoliated cell samples (without DNA extraction) yielded results consistent with hospital reports. In summary, the outstanding performance of the biphasic multiplex PCR assay makes it a promising technology for applications demanding multiple, ultrasensitive, and reliable detections, including clinical diagnostics, environmental monitoring, and food safety.

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A novel electrochemiluminescence (ECL) immunosensor based on the resonance energy transfer (RET) effect between europium-based metal-organic framework (Eu-MOF, ETM) and GO-PEI/Au was developed for detecting neuron-specific enolase (NSE). First, using 4’,5’-Bis(4-carboxyphenyl)-[1,1’:2’,1”-terphenyl]-4,4”-dicarboxylic acid (TCPB) as the ligand, we synthesized an efficient and stable ECL emitter (ETM) as the signaling substrate. Due to efficient spectral overlap between the ECL emission spectrum of ETM and the UV-vis absorption spectrum of GO-PEI/Au, the ECL emission signal of ETM can be expeditiously quenched. Consequently, the ECL varied with the quenching efficiency of the immunosensor, which correlated with the target analyte concentration, enabling quantitative detection of NSE. The developed straightforward and cost-effective immunosensor exhibited outstanding sensitivity and selectivity in identifying NSE within the 10 fg mL^− 1 to 100 ng mL^− 1 range with an impressively low limit of detection (LOD) of 1.26 fg mL^− 1. The immunosensor was successfully applied to quantify NSE in clinical human serum samples. Furthermore, by substituting the quenching probe, this platform can be readily adapted for detecting diverse biomarkers, demonstrating significant potential utility. To sum up, based on the ECL-RET strategy, a highly sensitive ECL immunosensor for NSE detection was constructed. It incorporated a novel ECL emitter (ETM) and established a new energy donor-acceptor pair, which demonstrated effective preliminary analysis of clinical samples.

A novel hydrophilic adsorbent of maltose-functionalized magnetic graphene covalent organic frameworks (denoted as MagGO@COF@Maltose) composites was designed and fabricated for highly selective enrichment of glycopeptides. The COF shell coating on the surface of magnetic graphene could provide highly abundant anchors to introduce large amount of hydrophilic maltose which endowed the composites with superior hydrophilicity. Benefited from this, the MagGO@COF@Maltose composites exhibited exceptional enrichment efficiency including high enrichment sensitivity (0.1 fmol µL^− 1), excelent enrichment selectivity (1:2000, horseradish peroxidase (HRP) tryptic digest to bovine serum albumin (BSA) tryptic digest) and high adsorption capacity (100 µg mg^− 1). In addition, the MagGO@COF@Maltose composites possessed rapid magnetic responses, good reusability and long-term storage stability. Finally, 279 endogenous N-glycopeptides derived from 70 glycoproteins with 78 N-glycosylation sites were enriched by the MagGO@COF@Maltose composites from human saliva sample, demonstrating their great potential in highly selective enrichment of glycopeptides from complex biological samples for comprehensive glycoproteomic determination.

A sensing platform has been developed based on the synergistic combination of gold-platinum nanoparticles (Au-PtNPs) with hydroxylated multiwalled carbon nanotubes (MWCNT-OH) as a conductive material for the sensitive detection of carbaryl in agricultural products. The nanocomposite, consisting of Au-PtNPs/MWCNT-OH, was deposited on a glassy carbon electrode (GCE) via simple drop-casting and further investigated for its electrochemical performance as a sensing platform for detecting carbaryl. Additionally, different instrumentation techniques, including Raman and Fourier-transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), field emission scanning electron microscopy-energy dispersive spectroscopy (FESEM-EDS), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS), were employed to characterise the surface morphology and structural properties of the Au-PtNPs/MWCNT-OH nanocomposite. Based on the electrochemical investigation, the proposed electrode, Au-PtNPs/MWCNT-OH-modified glassy carbon electrode, exhibited a broad linear range for carbaryl (0.4–600 µM), a low limit of detection (0.11 µM), and good stability and reproducibility (RSD < 5%). Moreover, the proposed electrode has been investigated for its selectivity in the presence of 11 different interfering species (paraoxon-ethyl, diazinon, acephate, thiamine, ascorbic acid, glucose, urea, MgSO₄, FeSO₄, Zn(NO₃)₂, and NaNO₃), demonstrating satisfactory selectivity. Further examination of this proposed electrode to determine carbaryl concentration in two different samples (rice and corn) yielded results with acceptable recovery, suggesting the potential for further development as a novel point-of-care platform for the rapid detection of pesticide residues in agricultural samples.

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To metal-organic frameworks (MOFs) composite materials with excellent luminescent properties, MOF-808@ZIF-8 and CDs@ZIF-8, were utilized to design a fluorescence sensor array. The sensor array was applied to the detection of ten heavy metal ions (Ag⁺, Ba²⁺, Cd²⁺, CrO₄²⁻, Cu²⁺, Fe³⁺, Fe²⁺ and Ni²⁺, Pb²⁺, Zn²⁺) in water. The interactions between the heavy metals and the MOF-based composites, as well as inner filter effect (IEF) mediated mechanisms, enables these ions to selectively alter the luminescent properties of MOF-808@ZIF-8 and CDs@ZIF-8, producing unique fluorescence signatures, facilitating precise identification. In particular, it enables the quantitative detection of Fe²⁺, Fe³⁺, and CrO₄²⁻, with detection limits reaching 241, 84 and 178 nM, respectively. These unique optical responses are subsequently analyzed and classified using pattern recognition algorithms. Significantly, the proposed strategy has been successfully applied to the detection of heavy metals in real water samples. This study proposes a rapid analytical method for identifying heavy metals in water, which has a promising application prospect in real-time monitoring of various pollutants in the water environment.

A novel fabric-based, highly sensitive enzymatic glucose biosensor is reported with dual-sensing technique, integrating both colorimetric and electrochemical methods on a 3D origami platform engineered using eco-sustainable & biodegradable starch-based biopolymer as an additional sensing layer. The study also compares the effectiveness of starch as a much more sensitive coating over traditionally used chitosan with improved LOD. Further, the unique origami design and multi-modal sensing, makes it highly suitable for wearable and POC applications. The 3D origami configuration allows compact folding and fluid manipulation through capillary action, obviating the need for external power sources. The dual-mode detection improves reliability and offers complementary outputs for enhanced diagnostic accuracy demonstrating ultra-high sensitivity with LOD of 10 pM and LOQ of ~ 440 pM for glucose within a linear range of 10 mM to 10 pM for electrochemical and 10 mM to 0.1 µM for colorimetric technique along with a device shelf-life of ~ 30 days under normal conditions. Efficacy of the fabricated glucose sensor has also been tested with real-time human sweat samples under fasting as well as 1 h after post breakfast. The major novelty lies in the exploitation of long-chain polymeric groups like starch (polysaccharide) to trap colored iodide complexes formed even at ultra-low glucose concentrations thereby accurately identifying picomolar level of its own monomer viz. glucose (monosaccharide) thereby acting as a potential substitute of chitosan in future devices. Future research will aim to enhance sensor shelf life by improving starch stability against moisture and microbial degradation for prolonged usage. Nevertheless, this innovative approach highlights a promising direction in the development of green, wearable highly sensitive biosensors for continuous and non-invasive health monitoring.

Graphical Abstract

A 3D-printed customizable MagnetoChip platform is introduced featuring Wi-Fi communication with a smartphone-controlled magnetic particle manipulation system integrated with a single-use capillary-driven microfluidic chip. This platform enables the colorimetric detection of luteinizing hormone (LH), a potential marker in sports doping. The system employs a sandwich immunoassay approach, where gold nanoparticles functionalized with horseradish peroxidase (HRP) enzyme and antibodies are used to capture and detect LH. 3,3’,5,5’-tetramethylbenzidine (TMB) dye was also used as a colorimetric substrate. Magnetic particles were employed for analyte enrichment, and their movement inside the microfluidic chip was remotely controlled via Raspberry Pi Pico with a stepper motor. Image processing optimizations were performed using ImageJ. The code was then embedded in Python for automation, and the user interface was created with a graphical user interface (GUI). The colorimetric outputs were analyzed using Red-Green-Blue (RGB) analysis, and the results demonstrated a strong correlation with analyte concentration, with a regression coefficient (R²) of 0.9975. The method was validated through ultraviolet-visible spectroscopy (UV-vis) measurement of the reaction result, while the sandwich immunoassay complex was confirmed with Surface-Enhanced Raman Scattering (SERS). Our developed platform offers a promising, user-friendly tool for rapid and accurate bioanalyte detection, with potential applications in sports doping control, clinical diagnostics, and point-of-care testing.

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