Microchimica Acta最新文献

Azvudine, a nucleoside analog antiviral agent approved for COVID-19 and HIV treatment, requires precise analytical methods for therapeutic drug monitoring and pharmacokinetic studies. This study presents the first strain-promoted azide-alkyne cycloaddition (SPAAC)-based fluorometric method for azvudine determination. The innovative methodology exploits the unique structural feature of azvudine containing an azide functional group, enabling highly selective covalent binding with dibenzocyclooctyne (DBCO)-functionalized carbon dots through copper-free click chemistry, resulting in concentration-dependent aggregation-induced fluorescence quenching. The method demonstrates excellent analytical performance with linear response in the range 2.0-150.0 ng/mL (R² = 0.9987), and achieves a limit of detection of 0.87 ng/mL. The bioorthogonal SPAAC reaction ensures exceptional selectivity, with no significant interference observed from endogenous plasma components, co-administered medications, or structurally related compounds. The method’s successful validation in complex biological matrices demonstrates robust extraction recoveries of 96.50-99.25% across clinically relevant concentrations, with relative standard deviations below 4%. Comprehensive application to real plasma samples from drug-treated human volunteers confirms the method’s practical utility for pharmacokinetic studies. This SPAAC-based fluorometric approach offers significant advantages over existing LC-MS/MS methods, including simplified sample preparation, reduced instrumentation costs, enhanced accessibility, and suitability for high-throughput therapeutic drug monitoring applications while maintaining comparable analytical performance.

Burkholderia gladioli pv. cocovenenans (B. gladioli C.) poses a threat to consumer health, making strengthen supervision of B. gladioli C. essential. A dual-readout lateral flow biosensor was described based on the combined colorimetric and magnetic properties of polydopamine-coated Fe₃O₄ magnetic nanospheres (Fe₃O₄@PDA MNSs). The biosensor utilized a pair of monoclonal antibodies (mAb) as specific recognition module for point-of-care detection of B. gladioli C. The mAbs demonstrated a limit of detection (LOD) of 4.17 × 10⁴ CFU mL^− 1 for B. gladioli C. via sandwich ELISA. The developed Fe₃O₄@PDA-based lateral flow assay (LFA) utilized immunomagnetic separation and enrichment capabilities of Fe₃O₄@PDA-mAb probe for sample pretreatment. This assay facilitated both colorimetric and magnetic analysis modes, allowing for a visual LOD of 1.0 × 10⁴ CFU mL^− 1 and a quantitative LOD of 2.32 × 10³ CFU mL^− 1. Compared with the gold nanoparticles-based LFA, this method achieved an approximately ninefold increase in detection sensitivity. Moreover, the assay exhibited reliable performance with recoveries ranging from 81.0% to 103.5% in rice noodle and milk samples. The validation with a panel of 20 milk samples further confirmed its potential for application to complex matrix. These results indicated that the proposed Fe₃O₄@PDA-based LFA offered a practical and rapid solution for screening B. gladioli C. contaminants in food safety application.

A portable, sensitive and low-cost immuno-detection microfluidic device for on-site application has been developed. The microfluidic device comprised a mask stereolithography (MSL)-based 3D-printed microfluidic chip and a handheld chemiluminescence reader. The MSL-fabricated microfluidic chip is characterized by its fast and economical prototype production process. Furthermore, the naturally generated micro-pits and micro-wavy structures during the printing process offered abundant surface area for antibody binding, which was beneficial for the assay sensitivity. The matched compact and lightweight chemiluminescence reader was designed for handheld use without compromising performance in signal intensity measurements, which were as sensitive as the commercial microplate reader. Employing this device, we developed a fast and simple detection workflow for the vital inflammation-related biomarker interleukin-6 (IL-6). Under suitable conditions, the device achieved a low limit of detection (LOD) of 0.5 pg/mL and a wide quantitative range from 0 to 800 pg/mL, covering the physiological levels of IL-6 in the human body. Moreover, validation studies involving 35 real samples and recovery analysis of IL-6-spiked serum samples confirmed the reliability and feasibility of the device for real-world applications. Capitalizing on its advantages, the microfluidic device demonstrates significant potential for on-site immunodetection applications in resource-limited settings.

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Convenient synthesis of functionalized CuS quantum dots (CuS QDs) with good biocompatibility in aqueous solution remains a significant obstacle. To overcome these limitations, a microwave-assisted one-pot method was developed to synthesize ultrasmall, cysteine-capped CuS QDs in aqueous phase. These CuS QDs exhibit outstanding optical properties, as well as excellent water dispersibility and stability. Based on these advantages, CuS QDs can be employed as a simple, rapid, and efficient fluorescent nanosensing platform for the selective detection of Ag⁺ across a wide concentration range (1–250 µM). Notably, the sensing system features a rapid response time (60 s) and a large Stokes shift (115 nm), which contribute to improved detection efficiency and sensitivity. Moreover, the system exhibits exceptional selectivity for Ag⁺ against a range of common metal ions via a fluorescence quenching mechanism. The underlying detection mechanism involves an Ag⁺-induced cation exchange process, resulting in the release of Cu²⁺ from the CuS QDs. Importantly, this sensing strategy has been successfully applied to the detection of Ag⁺ in real water samples, demonstrating high recovery rates. Additionally, the low toxicity and superior biocompatibility of the CuS QDs enable their further application in Ag⁺ detection within living cells. In summary, the CuS QD-based fluorescent probe offers a promising platform for environmental monitoring and biological diagnostics.

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A dual-functional fluorescence sensor and adsorbent, BH@SNP, was engineered by grafting a designed Schiff base ligand — (E)-4-((5-bromo-2-hydroxybenzylidene)amino)-3-hydroxynaphthalene-1-sulfonic acid — onto mesoporous silica nanoparticles synthesized from rice husk biowaste. Detailed SEM/TEM, XRD, BET, and DFT analyses confirm the formation of an amorphous, high‐surface‐area (412 m²/g) network with uniform pores and electronic characteristics optimized to suppress photoinduced electron transfer. Under mildly acidic conditions (pH 4.5), BH@SNP exhibits rapid fluorescence “turn-off” toward Cr(VI) oxyanions, achieving a 9.83 ng/mL detection limit and equilibrium response within 180 s. The sensor maintains ≥ 80% of its initial fluorescence output after one year of storage and retains > 80% activity over seven regeneration cycles using mild EDTA treatment. Concurrent adsorption studies reveal 75% Cr(VI) uptake within 30 min and a maximum capacity of 45.9 mg/g, following Langmuir and pseudo–second‐order kinetics. In both spiked laboratory solutions and real electroplating wastewater, BH@SNP achieves > 94.8% removal efficiency. Combining agricultural‐waste valorization with integrated trace‐level detection and remediation using BH@SNP establishes a scalable, circular-economy platform for sustainable water treatment and heavy‐metal monitoring.

A dual-mode sensor with a wide concentration range for NH₄⁺ detection was presented based on the confined effect of zeolitic imidazole framework-8 (ZIF-8) combined with o-phthalaldehyde (OPA). OPA@ZIF-8 was ingeniously designed by the ternary phase diagram to obtain the best detection performance. Benefiting from the confined effect of ZIF-8, OPA actively collided and reacted with NH₄⁺. This sensor can realize the wide concentration ranging over four orders of magnitudes for NH₄⁺ determination. The low concentrations of NH₄⁺ triggered a significant fluorescent response with a detection limit as low as 0.054 µM, while the high concentrations can produce a colorimetric signal from colorless to blue. The mechanism study showed that the confined effect of ZIF-8 effectively accelerates the reaction to reach equilibrium, addressing the issue of poor stability of reaction between OPA and NH₄⁺ reaction product. In the actual sample detection, the recovery reached 91.1%-97.9%, verifying the reliability of this method. This study not only provides a feasible method for detecting NH₄⁺ in various environments, but also offers insights into the research of sensing systems under the confinement effect regulation of nanomaterials.

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Volatile sulfur compounds (VSCs) in human exhaled breath (EB) are considered as biomarkers of halitosis. Convenient and reliable detection of VSCs has significance for confirming oral health. Herein, copper-based metal-organic framework (Cu-TPPE) was synthesized by utilizing aggregation-induced emission (AIE) phenomenon of tetrakis(4-pyridylphenyl)ethylene (TPPE) ligand on paper. Due to electron transfer between Cu²⁺ and TPPE, the aggregation-induced emission of TPPE was quenched. In the presence of VSCs, the affinity between S and Cu led to delocalization of Cu in Cu-TPPE, thus recovering the aggregation-induced chemiluminescence emission between TPPE and bis(2,4,6-trichlorophenyl)oxalate (TCPO)-H₂O₂. Based on this principle, selective and sensitive determination of VSCs in human EB was achieved. The linear range of quantification of H₂S was 0.07-8.0 ppm, and the detection limit was 0.03 ppm. This paper-based chemiluminescence platform has been applied to the detection of VSCs in real breath samples.

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A novel strategy is presented for constructing ratiometric fluorescent detection platform based on terbium(Ⅲ) ion as a single luminescence center, enabling sensing of permanganate ions (MnO₄^‒) in water. The approach leverages the differential quenching mechanisms of MnO₄^‒ on distinct emission bands of terbium-based metal-organic frameworks (Tb-MOFs), using the intensity ratio of specific emission wavelengths (I₅₄₈/I₆₂₂) as the detection signal for MnO₄^‒ quantification. A ratiometric probe [Tb(BCB)(DMF)]·(DMF)_1.5(H₂O)₂ (H₃BCB: 4,4’,4’’-benzenetricarbonyltribenzoic acid) (1) was developed, demonstrating high selectivity, sensitivity, and anti-interference capability toward MnO₄^‒. The study of quenching mechanism reveals that the 622 nm emission is quenched solely by the inner filter effect (IFE), whereas the 548 nm emission undergoes synergistic quenching by IFE and Förster resonance energy transfer (FRET). This differential quenching leads to a distinct decrease in I₅₄₈/I₆₂₂, forming a robust ratiometric sensing platform. Notably, the method eliminates interference from dichromate ions (Cr₂O₇^2‒). The strategy’s generality is validated by a second Tb-MOF ([Tb(cpia)(H₂O)₂]_n·nH₂O (H₃cpia: 5-(4-carboxyphenoxy) isophthalic acid) (2)), which also functions as a ratiometric probe for MnO₄^‒. These findings establish a universal design principle for constructing single-luminescence-center ratiometric fluorescence platforms.

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A magnetic graphene oxide assisted-DNAzyme aptasensor is presented designed and fabricated for simple colorimetric detection of Salmonella Typhimurium in contaminated water. Superparamagnetic Fe₃O₄ nanoparticles were directly synthesized on graphene oxide sheets and then a DNAzyme-probe (G5Zyme) immobilized on sheets. The catalytic core of G5Zyme consists of an exposed guanine-rich loop, which becomes active only upon forming a duplex with the Salmonella aptamer. In this activated state, it catalyzes the oxidation of TMB in the presence of hydrogen peroxide, producing a distinct colorimetric signal. In negative samples (healthy water without Salmonella), free aptamers detach the G5Zyme from graphene oxide sheets and hybridize with it, thereby activating the enzyme leads to produce a color. In contrast, in positive samples containing Salmonella, the aptamers preferentially bind to the bacteria, and following magnetic separation, the G5Zyme is removed from the reaction system, resulting in the suppression of color development. The nanobiosensor enabled highly sensitive detection of Salmonella (1 CFU/mL in water), demonstrating excellent specificity and robust reproducibility within 3 h. Its performance surpassed conventional culture methods and was comparable to PCR assays without requiring DNA extraction.