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A cDNA sensor based on gold nanoparticles (Au) supported on nickel metal-organic framework nanosheets (MOF-NS) modified fluorine-tin oxide (FTO) glass electrode for the ultrasensitive and selective detection of miRNA-128 biomarker associated with the progression of Alzheimer's disease (AD) has been reported. The MOF-NS and Au nanoparticles were electrodeposited onto FTO electrode using chronoamperometry to immobilize 5'-biotinylated DNA (btn-cDNA) complementary to miRNA-128 by streptavidin-biotin interaction, generating the modified electrode (btn-cDNA/SV/Au/MOF-NS/FTO). The fabricated electrode was characterized using various surface characterization techniques, including FESEM, XPS, FTIR, and electrochemical methods. The fabricated electrode was then utilized for the selective detection of miRNA-128 using electrochemical impedance spectroscopy. The results indicated a linear response range of 1.0 × 10^-1 fM-1.0 × 10² nM with limit of detection of 0.017 fM, and sensitivity of 180.11 Ω fM^-1cm^-2. Moreover, the cDNA sensor showed satisfactory performance with real serum samples from AD patients and healthy individuals, as validated by real time-PCR technique with area under curve of 0.93 and a sensitivity of 90%, respectively, demonstrating the potential of present cDNA sensing approach in the biomedical field.

Triacylglycerols (TGs) represent one of the most abundant lipid classes in biological and food matrices; however, their structural characterization by mass spectrometry remains challenging because conventional workflows often provide only sum composition information. In the present study, an aza-Paternò-Büchi (aPB) derivatization strategy based on 6-azauracil was optimized and applied for negative-ion-mode, isomer-resolved analysis of TGs by high-resolution mass spectrometry. Reaction conditions were systematically investigated through solvent optimization, mixture design modeling, and kinetic studies. Moreover, the ionization and fragmentation behavior of aPB-derivatized TGs was comprehensively investigated, revealing distinct fragmentation pathways associated with charge localization effects in neutral lipids. Application to complex matrices demonstrated the feasibility of the approach, providing direct access to TG regioisomer distributions in human plasma and vegetable seed oils. Overall, the proposed strategy enables untargeted and double-bond-resolved annotation of TGs in complex matrices while maintaining straightforward sample preparation and compatibility with routine lipidomics workflows. For the first time, negative-ion mode was employed for TG annotation, expanding the molecular information accessible in TG lipidomics and food analysis.

This study introduces a novel rapid and efficient analytical approach for the determination of PGEs, excluding Os, in rock samples by ICP-MS. This approach combines effective matrix removal in silicate rock samples through the formation of insoluble fluorides during microwave-assisted digestion and the volatilization of silicon as SiF₄ with the capability of ICP-MS to quantify target isotopes at very low signal intensities (10-100 cps) using optimized acquisition parameters. Moreover, the ability to perform ICP-MS measurements at such low signal intensities also enables matrix reduction in other sample types, such as ores, through simple dilution while maintaining sufficient analytical sensitivity. Since proposed strategy employs fast microwave dissolution of PGEs together with their reliable and accurate determination, without the need for complex and time-consuming matrix-separation procedures such as ion-exchange chromatography or tellurium co-precipitation, the analytical workflow is significantly simplified, and the overall analysis time is reduced several-fold compared with conventional methods. At the same time, detection and quantitation limits are below 0.1 and 0.5 ng/g, respectively, for all analytes except Pd, for which the corresponding limits are 0.18 and 0.9 ng/g, enabling the determination of PGEs in variety rock types. The new method was verified using six rocks certified reference materials (CRMs) MUH-1 (harzburgite), NCS-DC73354/GBW07290 (peridotite), OKUM (komatiite), and UMT-1 (ultramafic ore tailings), WMS-1a (massive sulfide) and NCS-DC73356/GBW07292 (chromitite). The results obtained showed excellent agreement with both certified values and previously published data, with the vast majority of measurements falling within stated uncertainties or within ±10% of certified values.

Elucidating the effects of pollutants at the level of primary single cells is of great significance for an in-depth understanding of their health risks and toxicological mechanisms. N,N'-bis (1,4-dimethylpentyl)-p-phenylenediamine quinone (77PDQ) is an emerging environmental contaminant with multiple biological toxicities; however, its toxic effects at the primary single-cell level remain unexplored. In this study, we established a high-throughput single-cell metabolomics platform based on label-free CyESI-MS and applied it to the analysis of freshly isolated primary mouse liver cells for toxicological assessment of 77PDQ exposure at single-cell resolution. This strategy enabled us to capture cell-to-cell metabolic heterogeneity that was lost in conventional bulk measurements. Analysis of primary mouse liver cells revealed 181 significantly altered metabolites (|Log₂FC|>1, p < 0.05) following 77PDQ exposure. Pathway analysis demonstrated substantial disruptions in glycerophospholipid, arginine-proline, and beta-alanine metabolism. Eight lipid biomarkers (PC (41:6), PS (31:4), Cer (d41:1), TAG (53:2), LPG (18:1), SM (d42:3), FA (23:0), PA (36:2)) showed excellent diagnostic capacity (AUC>0.9). Our study provides the single-cell metabolomics evidence of 77PDQ hepatotoxicity and offers new mechanistic insights into this emerging environmental contaminant.

In this work, a high-performance, room-temperature-operated acetone gas sensor is developed based on cladding-modified optical fiber functionalized with hierarchical flower-like ZnO@Ag₂O nanostructures. Unlike conventional metal-oxide gas sensors operating at elevated temperatures, the formation of a p-n heterojunction between p-type Ag₂O and n-type ZnO facilitates efficient charge separation and significantly lowers the activation energy for acetone oxidation, enabling enhanced sensing at ambient conditions. The structural and morphological properties were characterized by X-ray diffraction, FESEM, XPS, and FTIR. The sensing performance was achieved by coating the modified fiber cladding with ZnO@Ag₂O, where evanescent-field interaction and adsorption-induced optical property changes govern the sensing mechanism, as validated by COMSOL Multiphysics simulations. The flower-like morphology provides a larger surface area and abundant active sites, resulting in superior sensing performance compared to pristine ZnO nps. The performance parameters of the developed sensor include a sensitivity of 11.37/ppm, a limit of detection of 0.85 ppm, and response and recovery times of 14 s and 60 s, respectively, compared to pristine ZnO nps. Additionally, the sensor exhibits good selectivity for acetone over different interfering VOC species. Owing to its spark-free operation, low power consumption, and immunity to electromagnetic interference, the proposed sensing platform presents a promising solution for real-time acetone detection in industrial process monitoring and non-invasive biomedical diagnostics.

The widespread use of glyphosate in agriculture has raised concerns about environmental contamination and associated health risks, creating an urgent need for rapid, sensitive, and field-deployable analytical tools. In this work, Zr/Eu-metal-organic framework (Zr/Eu-MOFs) as an integrated bimetallic ratiometric fluorescent hydrogel sensor for fast and highly sensitive visual detection of glyphosate has been developed. By doping Eu³⁺ into a robust Zr-based MOF framework, Zr/Eu-MOFs exhibit dual-emission bands at 445 and 618 nm, enabling an intrinsic self-referenced signal without multicomponent assembly. Upon glyphosate addition, the sensor responds within 10 s. Zr/Eu-MOFs display a reliable ratiometric response over 0.05 - 10.0 mg/L with a low detection limit of 0.03 mg/L (0.2 μmol/L), which is far below the permissible maximum residue limit (MRL) for drinking water by the US EPA and China (4.1 μmol/L). Mechanistic evidence indicates that glyphosate forms P-O-Zr coordination linkages and interfacial interactions which modulate the ligand-to-metal charge transfer (LMCT) process, resulting in an enhanced ratiometric fluorescence response at 445 nm, while the Eu³⁺ emission at 618 nm remains essentially unchanged. Moreover, an agarose hydrogel format coupled with smartphone image analysis enables rapid visual detection. A spraying-enabled fluorescence imaging strategy further allows rapid screening of glyphosate contamination on leaves, apple surfaces, and soil-water matrices under UV illumination. Overall, this work provides a facile, integrated, and visually readable ratiometric platform for on-site glyphosate monitoring.

Accurate detection of microRNAs is of great significance for the clinical diagnosis and therapeutic guidance of cancer. Herein, we have established an isothermal self-catalytic DNA circuit that can combine an autocatalytic hairpin assembly (ACHA) converter with autocatalytic hybridization chain reaction (AHCR) amplification for the sensitive detection of miRNA-21. HCR is initiated by the recognition of the target analyte, generating new trigger strands that subsequently activate the CHA amplifier. One terminus of the CHA amplifier is engineered to expose the identical HCR initiator sequence, thereby enabling sustained HCR propagation. The DNAzyme moiety at the opposite terminus functions as a fluorescent signal reporter, efficiently cleaving the fluorogenic reporter probe. Therefore, the self-catalytic feedback loop between the HCR and CHA systems allows trace targets to produce fluorescence signals with exponential amplification. This circuit conducted a sensitive, reliable and universal analysis of miRNA-21, with a detection limit of 33.4 fM. Self-feedback cascade circuits provide a promising tool for molecular sensing in complex biological environments, this cascaded circuit can be used for the analysis of miRNA-21 in human serum samples. It has broad application prospects in low-abundance biomolecular sensing and early diagnosis of diseases.

Copper ions (Cu²⁺) are essential micronutrients but become hazardous when accumulated in excess, necessitating reliable, sensitive, and field-deployable detection methods. Herein, we report a fluorescent Mn-based MOF nanozyme (Mn-TCPP) that exhibits intrinsic oxidase-like activity, capable of catalyzing the oxidation of non-fluorescent o-phenylenediamine (OPD) to fluorescent 2,3-diaminophenazine (DAP) with an emission peak at 560 nm, while the Mn-TCPP itself displays characteristic fluorescence at 655 nm. Upon exposure to Cu²⁺, the stronger affinity of Cu²⁺ toward the porphyrinic TCPP ligand displaces Mn²⁺ from the framework, forming Cu-TCPP. This metal-exchange process simultaneously quenches the 655 nm fluorescence of the MOF and attenuates its oxidase-mimicking activity, whereas free Cu²⁺ in solution independently catalyzes OPD oxidation, further enhancing the 560 nm emission. Leveraging this dual-response mechanism, we develop a ratiometric fluorescence sensing strategy for Cu²⁺ detection based on the intensity ratio F₅₆₀/F₆₅₅. The calibration curve follows a linear equation: F₅₆₀/F₆₅₅ = 0.201x-0.001 (0.2-10 μM, R² = 0.985) and y = 0.002x+2.061 (10-100 μM, R² = 0.994) with the limit of detection (LOD) of 81 nM (S/N = 3). The sensor exhibits excellent selectivity over competing metal ions, and the method reliability is validated by standard addition recovery experiments in real water and rice samples. Furthermore, the Mn-TCPP nanozyme is embedded into an agarose hydrogel matrix, enabling visual, instrument-free monitoring of Cu²⁺ contamination: increasing Cu²⁺ concentrations induce a discernible fluorescence color transition from orange to yellow under 365 nm illumination. This work presents a tunable MOF platform that exploits competitive targets synchronous modulation of fluorescence and enzyme-mimicking activity, providing a robust, selective, and field-deployable ratiometric sensor for Cu²⁺.

Antibiotic-resistant bacterial infections pose a global health crisis, driving the need for innovative diagnostic approaches. Conventional methods for detecting resistant strains and antibiotic susceptibility testing (AST) are often limited by long assay times, low sensitivity, and operational complexity. Herein, a novel gelatinase-responsive cascade microfluidic chemiluminescence (CL) biosensor was developed for ultrasensitive detection of gelatinase-producing bacteria, with phenotypic AST validated using Staphylococcus aureus (S. aureus) as the model pathogen. Peptide-DNA probes were designed to respond to gelatinase secreted by bacteria remain metabolically active following antibiotic exposure. Bacterial gelatinase cleaves peptides to release initiator single-stranded DNA (ssDNA), triggering hybridization chain reaction (HCR) amplification in micropillar-structured microchannels. Through streptavidin-biotin interaction, poly-horseradish peroxidase (poly-HRP) is anchored in the channel to catalyze luminol based CL. This biosensor achieves high specificity and sensitivity, with a detection limit of 15 CFU/mL, which is better or comparable to previously reported biosensors. Moreover, the potential clinical applicability of this platform is further verified by testing four clinical S. aureus strains against five antibiotics, yielding 95% categorical agreement rate with standard AST methods. The area under the receiver operating characteristic ROC curve (AUC) was 0.944, close to the ideal value of 1, indicating excellent diagnostic performance for AST. The assay time from isolated colonies to AST result takes approximately 4-5 h. Featuring portability and low cost, the platform enables universal bacterial AST, providing a reliable tool for precise antimicrobial therapy and antimicrobial resistance control.