DNA tetrahedron-radiated nanonetwork for the dual-mode detection of FEN1 and T4 PNK activities.

Analysis of weight-loss compounds in health supplements by ultrasonic extraction, dispersive sorbent cleanup, and liquid chromatography tandem mass spectrometry quantification.

Specific electroanalysis of neurotransmitters in the brain, bloodstream, cerebrospinal fluid (CSF), or at the cellular level critically depends on the availability of miniaturized electrodes for aptasensing. Yet, with electrode miniaturization, sensitivity of analysis and limits of detection (LOD) can be compromised. Here, we adapted the RNA-aptamer-based macroelectrode assay for dopamine to the microelectrode format, by using gold-plated carbon fiber microelectrodes (CFE), modified via thiol chemistry with cysteamine and an RNA aptamer, for specific dopamine detection. The sensitivity of analysis with gold-plated cylindrical microelectrodes improved 90-fold, to 9.75μAμM-1cm-2 (at +0.100V) vs. 108nAμM-1cm-2 (at optimal +0.185V) shown with gold disk macroelectrodes, with LOD being 60 and 100nM, in PBS and in artificial CSF, respectively. Yet, epinephrine interfered at 0.1V. At 0.05V, the sensitivity dropped to 4.62μAμM-1cm-2 but the RNA-aptamer/cysteamine-modified CFEs demonstrated excellent selectivity for dopamine over epinephrine, norepinephrine, L-DOPA, DOPAC, and uric and ascorbic acids. These findings suggest a straightforward strategy for constructing biospecific aptamer-based microelectrodes. However, in matrices more complex than CSF, such as serum, dopamine oxidation was inhibited. Therefore, effective monitoring of dopamine levels in blood using aptamer microelectrodes will likely require the use of protective membranes.

A simple and instrument-free colorimetric method for quantitative analysis is reported, in which analyte concentration is determined by measuring the length of a colored adsorption band formed in a packed silica gel column. The proposed method employs a miniature silica gel column that acts as a signal transducer after it adsorbs the colored compound from a solution during its flow in the column. The length of this band increases proportionally with analyte concentration, which enables quantitative detection via simple distance measurement. A theoretical model was developed to describe the relationship between solute concentration, adsorption behavior, and band propagation along the column. The principle was validated via the detection of both iron ions and enzyme-mediated glutamic acid. For Fe2+ analysis, the o-phenanthroline complexation method shows a level of sensitivity comparable to that of conventional spectrophotometry, which enables an almost quantitative recovery of trace iron in tap water. The limit of detection (LOD) and the limit of quantification (LOQ) were estimated to be 0.20μM and 0.60μM for the proposed method and 0.23μM and 0.70μM for spectrophotometry, respectively. The approach was further extended to glutamate detection using a cascade reaction involving glutamate oxidase and horseradish peroxidase with N-benzoyl leucomethylene blue as the chromogenic substrate. The LOD and the LOQ of the proposed method were 0.08 and 0.25μM, and both values are superior to the 0.24μM and 0.73μM obtained using a microplate reader. By integrating preconcentration with a distance-based readout, this method provides a simple yet highly sensitive analytical platform and establishes distance as a quantitative signal for colorimetric detection.

Detection of nucleotides with gas chromatography - mass spectrometry (GC-MS) using trimethylsulfonium hydroxide (TMSH) and tetramethylammonium hydroxide (TMAH) thermochemolysis: Characterization, comparison and application to future experiments onboard space probes.

Novel boronate affinity molecularly imprinted nanomaterials for selective dispersive magnetic solid-phase extraction of catecholamines from equine urine

Development of emergency radio-bioassay method for Th, Pu, Np and U in urine samples using single-column chromatography, automated operation system and ICP-MS/MS.

Cysteine exerts surface polarization effect on BiOCOOH for photoelectrochemical detection of small molecules.

Many bioanalytical methods result in the generation of colorimetric readouts, with color intensity providing information of the concentration of the targeted analyte. However, conventional absorbance readers often saturate at high analyte concentrations, requiring sample serial dilutions when the analyte studied can be present in a wide range of concentrations. Here, we present a portable reader based on a single-photon avalanche diode (SPAD) array performing in-pixel time-resolved photon counting to quantify absorbance over an extended dynamic range. The method relies on a lifetime-based measurement principle, in which absorbance is derived from the photon-arrival decay constant (τ) rather than steady-state intensity, enabling accurate quantification under high-flux conditions. We applied this approach to an influenza B nucleoprotein magnetic particle immunoassay. The SPAD-based reader maintained a monotonic response up to 64ngmL-1 within the useable dynamic range, compared to signal saturation above 12.5ngmL-1 for a commercial photometer, with limits of detection (LoD) and quantification (LoQ) of 0.0034 and 0.0949ngmL-1, respectively, while maintaining coefficients of variation (CV)<10%. A convolutional neural network trained on 16-bin histograms accurately inferred analyte concentration (R2=0.986), yielding results consistent with the τ-based calibration, thus demonstrating that the same time-resolved photon information can be quantitatively interpreted either through physical modeling or data-driven inference. By extending the useable absorbance range while preserving sensitivity, this approach improves key analytical figures of merit compared to commercial benchtop equipment, paving the way for high-performance portable point-of-care (PoC) solutions.

Examination of influence of microfluidic flow and antibody orientation on biosensor performance: A case study with CA125 electrochemical biosensor.

Synergistic effect of Co-MoS₂ and Au-rGO nanomaterials: Layer-by-layer electrochemical immunosensor realizes high selective trace detection of Aβ oligomers.

The persistent threat of foodborne pathogens, despite safety measures, underscores the urgent need for highly sensitive and rapid sensing technologies to prevent outbreaks and mitigate their devastating health and economic impacts. The evolution of sensing technologies, from enzyme-based biosensors to advanced immuno-based methods, highlights a continuous drive to improve sensitivity, speed, and feasibility in pathogen detection. Immuno-based biosensors have revolutionized pathogen detection by advancements in miniaturization, offering swift, sensitive, and cost-effective alternatives to traditional methods. Mainly, two categories of immuno-based biosensors have become largely demanding for POC; signal transduction-based, such as electrochemical, optical, and quartz crystal microbalance technologies, have significantly advanced pathogen detection by offering real-time, hyper-sensitive, and prompt monitoring capabilities, making them promising tools for field-deployable diagnostics. The second category, platform design-based immuno-based biosensors, such as lateral flow assays, microfluidic paper-based devices, and microchip-based devices, offer cost-effective, facile, and precise pathogen detection for use in food safety and outbreak prediction analysis. Nevertheless, numerous other biosensor types exist, but this review will focus on a few selective ones to enhance clarity and readability. The review shall summarize the state-of-the-art advancements in food pathogen sensing by immuno-based biosensors, their effectiveness, progress, and categories. Racing from qualification to quantification, the discussion will cover the challenges encountered and loopholes in the developed immuno-biosensing methodologies, including material-related issues (e.g., batch variability of nanomaterials, single-use paper substrates) and assay design (e.g., complex microfluidic architectures and multi-step protocols) that affect reproducibility, waste generation, and dependence on trained operators. It will reflect on a comparative study between the most recent emerging works based on good linear range, limit of detections (LODs), types of real samples utilized and short detection time for addressing their impact as POC devices. Unlike previous reviews that typically focus on isolated sensing mechanisms, this article provides a comparative analysis of both signal-transduction-based and platform-design-based immuno-biosensors, coupled with emphasis on recent advances relevant to point-of-care food pathogen detection.

Direct quantification of thallium(I) in water by ESI-MS via supramolecular recognition with cryptand[2.2.2

Double-clamp Schiff base ligand engineered Ru (II) complex exhibiting Zn2+-activated fluorescence for selective Zn2+ detection and live-cell imaging.

Enhancement of peroxidase-like activity of FeP-CoP3 via precursor-shell engineering for tannic acid detection in beverages.

Surface enhanced Raman spectroscopy-based biosensor using nano-sculptured thin film to detect glial fibrillary acidic protein (GFAP) in blast-exposed moderately injured rat serum.

Steric hindrance effect synergizing hole-trapping technique: High-Stability and high-accuracy Si/CdS n-n heterojunction photoelectrochemical biosensing of amyloid-β42.

Preparation and application of IgM monoclonal antibodies in half-smooth tongue sole (Cynoglossus semilaevis).

Spatially separated Cu2O/BiOI heterojunction and target-triggered DNA cascade amplification integrated highly sensitive self-powered photoelectrochemical biosensor.

Determination of multiple risk substances in porcine cultured meat biomass and washing solutions using LC-MS/MS: method development, validation, and risk assessment.