Microchimica Acta最新文献

An activatable photoacoustic probe based on metal-organic frameworks (MOFs) (denoted as MOFs@HRP&ABTS) was designed for highly sensitive detection and precise imaging of H₂O₂ in tumor microenvironment. The probe utilizes ZIF-8 as a pH-responsive carrier that undergoes selective degradation under acidic tumor conditions, enabling the controlled release of encapsulated horseradish peroxidase (HRP) and its substrate ABTS with tumor-specific precision. Upon release, HRP catalyzes the H₂O₂-dependent oxidation of ABTS to generate ABTS·⁺, a near-infrared-absorbing radical that elicits a significantly enhanced photoacoustic response. The system demonstrates a detection limit as low as 2.5 µM. Comprehensive experimental assessments confirm the probe’s high selectivity toward H₂O₂ and excellent biocompatibility. In vivo studies using MCF-7 tumor-bearing mouse models enabled high-contrast, noninvasive visualization of tumor regions via photoacoustic imaging. By integrating the confined catalytic environment provided by the MOFs architecture with effective enzymatic stabilization, this work establishes a ternary “carrier-enzyme-substrate” cooperative system that surmounts the limited tissue penetration depth inherent in conventional optical probes. The resulting nanoplatform combines deep-tissue penetration, ultrahigh sensitivity, and noninvasive readout capabilities, offering a promising strategy for the precise detection of tumor biomarkers.

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Meropenem (MEM), a broad-spectrum carbapenem antibiotic, has a narrow therapeutic window and high interindividual variability. Existing detection methods are often limited by complex operations, long turnaround times, and inadequate sensitivity. To overcome these challenges, this study developed a novel lateral flow immunochromatographic assay (LFIA) platform with synchronous triple-signal output for rapid and accurate MEM detection. A fluorescent membrane sensor was fabricated by integrating Rhodamine 6G (R6G) as a fluorescence donor into a nitrocellulose membrane. Isoniazid (INH, code 064) was selected as the optimal Raman reporter, enabling the synthesis of Raman nanospheres (R-Sphere⁰⁶⁴) capable of delivering colorimetric, surface-enhanced Raman scattering (SERS), and background fluorescence-quenched immunochromatographic assay (bFQICA) signals simultaneously. Density functional theory (DFT) calculations indicated that the adsorption of INH on the nanosphere surface involves an electron injection effect that promotes charge transfer, with an adsorption energy of -0.19 eV and a charge transfer amount of 0.14 e. The characteristic SERS peak at 1006 cm⁻¹ was attributed to the breathing vibration of the pyridine ring in INH. With a 15 min detection time, the platform offers LODs of 0.8 ng mL^− 1 (SERS) and 0.8 ng mL^− 1 (bFQICA), a shared LoQ of 1 ng mL^− 1, and a linear range of 1–10 ng mL^− 1. It demonstrated high stability, reproducibility, and specificity. Validation using 22 clinical samples showed strong correlation with standard clinical methods. The platform can be easily adapted to monitor other therapeutic drugs by replacing the specific antibody, offering a universal solution for clinical therapeutic drug monitoring (TDM).

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A post-synthetic modification strategy is presented to induce a chirality in red-emissive carbon dots (CDs) by covalent bonding with chiral isocyanates. The resulting chiral CDs exhibit circular dichroism signals in the 300–500 nm range with a dissymmetry factor of 8 × 10^− 5 at 345 nm, distinct from their chiral precursors. These chiral CDs maintain photoluminescence in the red spectral range (615–640 nm) and reasonably high quantum yield of 12–13%. Cytotoxicity assays reveal differential biocompatibility, with the R-enantiomer showing higher toxicity across multiple cell lines (H9c2, 4T1, HeLa, B16) compared to the S-enantiomer. The enantioselective interactions are modeled on example of dynamic system of CDs and tryptophan enantiomers, monitored by changes in CD spectra and molecular dynamics simulations. These findings highlight the potential of chiral CDs for applications in biosensing, chiral separation, and targeted therapy, providing a scalable and controllable synthesis route for red-emissive chiral nanomaterials.

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As the most active antioxidant in the flavonol family, quercetin (QR) exhibits favorable biochemical and pharmacological properties. Therefore, rapid and accurate determination of QR is of great importance. In this study, a π-conjugated molecule, 2,3,6,7,10,11-hexahydroxytriphenylene (HHTP) was employed to in-situ grow a conductive metal-organic framework (MOF) on CuCo-zeolitic imidazolate framework (CuCo-ZIF) by a simple one-step solvothermal coating method. This design enhances electron transfer, ultimately yielding a bimetallic MOF-on-MOF hybrid material (CuCo-ZIF@HHTP). The introduction of Cu improves the conductivity of the ZIF framework, while the π-π conjugation characteristic of HHTP further boosts the electrocatalytic performance of CuCo-ZIF. As an electroctalytic eletrode, an electrochemical sensor for sensitive detection of QR was developed, which exhibited excellent linear responses in two concentration ranges (0.25–35 µM and 35–155 µM) with an extremely low limit of detection (LOD) of 7.5 nM (S/N = 3). The sensor also demonstrated high selectivity and reproducibility, with successful application in the quantification of QR in food samples.

Graphical Abstract

A π-conjugated HHTP was coated on CuCo-ZIF via one-step solvothermal method to form CuCo-ZIF@HHTP with Cu enhancing conductivity and HHTP's π-π conjugation boosting electrocatalysis for sensitive QR detection in food samples.

In consideration of the severe hazards of perfluorooctane sulfonate (PFOS) pollution, this study presents a bifunctional luminescent ionic covalent organic framework (iCOF), N⁺-DT-COF, engineered for the simultaneous ultrasensitive detection and highly efficient removal of PFOS in water. The material was synthesized via post-functional modification by grafting quaternary ammonium cationic chains onto a parent spherical DT-COF framework, which was comprehensively confirmed through SEM, XPS, FT-IR, and PXRD analyses. This strategic modification induced a critical photophysical transition that converted the non-emissive DT-COF into a highly fluorescent material by disrupting its inherent π–π stacking. The resulting N⁺-DT-COF functioned as a superior sensor, achieving an ultra-low detection limit of 0.079 ng/L for PFOS via a fluorescence quenching mechanism, with a rapid response within 5 min and exceptional selectivity. Concurrently, it served as a powerful adsorbent, exhibiting a remarkable maximum adsorption capacity of 561.8 mg/g, following pseudo-second-order kinetics. Validation using real Pearl River water samples demonstrated not only high analytical accuracy (102.9–107.4% recovery) and precision (RSDs < 2.5% intra-day, < 3.1% inter-day), but N⁺-DT-COF also achieved complete PFOS removal, underscoring its dual-function capability. This work establishes a promising strategy for the integrated monitoring and remediation of PFOS contamination.

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Long-wavelength ratiometric fluorescent carbon dots for the detection of ciprofloxacin (CIP) and cobalt ion (Co²⁺) are reported. The carbon dots (D-CDs), which exhibit outstanding dual emission at 445 nm and 662 nm, are synthesized via a one-pot hydrothermal method using methylene blue as the sole precursor. The particle size of as-prepared D-CDs is approximately 2.28 nm. Interestingly, due to the aggregation between D-CDs and CIP through hydrogen bonding, efficient charge transfer is achieved in the aggregated state, which collectively induces an enhancement of blue fluorescence while the emission at 662 nm remains unchanged. This yields a ratiometric fluorescence response (F_445nm/F_662nm) across a concentration range 0.048 to 3.58 nM with a detection limit of 16.7 pM. Additionally, fluorescence of the D-CDs/CIP system can be effectively restored in a ratiometric manner due to the specific reaction between Co²⁺ and CIP, enabling the ratiometric quantitative assay of Co²⁺ with a detection limit of 14.7 nM. Notably, a smartphone-integrated colorimetric test strip enables on-site monitoring of CIP and Co²⁺, expanding environmental applications, which has been demonstrated by effective detection of CIP in milk and river water. Furthermore, a logic gate sensor is developed by harnessing this activated cascade effect to function as an intelligent probe for monitoring trace levels of CIP and Co²⁺. The D-CDs are successfully applied in cellular imaging, demonstrating their potential in sensing, bioimaging, and environmental analysis.

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Four lanthanide metal-organic frameworks (Ln-MOFs) with the same planar structure were successfully synthesized via the hydrothermal method：{DyL (H₂O)₃·5H₂O}ₙ (1), {HoL(H₂O)₃·5H₂O}ₙ (2),{ErL(H₂O)₃·5H₂O}ₙ (3), and {TmL (H₂O)₃·6H₂O}ₙ (4), where H₃L = 2,4,6-biphenyl tricarboxylic acid. All four Ln-MOFs crystallize in the triclinic P_-1 space group, exhibiting high phase purity, excellent thermal stability, and favorable luminescence properties. The Ln-MOFs powders were subsequently shaped into composite fluorescent films using a polymer embedding method for the sensing and detection of Fe³⁺, Cr₂O₇²⁻, aspartic acid (Asp), and tetracycline (Tcn) in aqueous solutions. It was found that 1@PMMA, 2@PMMA, and 4@PMMA exhibited significant recognition ability for Asp, with no notable differences among them. All three films could serve as fluorescence sensing probes for Asp. In contrast, 3@PMMA showed no distinct recognition ability for Asp. For the detection of Tcn, Fe³⁺, and Cr₂O₇²⁻, all four films performed comparably and can serve as specific fluorescent sensors for these analytes. Compared with powdered MOFs, these films are not only highly efficient, stable and recyclable but also portable and easy to operate. This device fabrication strategy lays the fundament for the application of the reported metal-organic frameworks in diverse areas such as environmental protection, pollution control, material innovation, and public health.

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A portable electrochemical sensor was developed using a screen-printed electrode modified by graphdiyne carbon dots and black phosphorene (GCDs@BP) nanocomposite, with the EmStat3 Blue potentiostat enabling real-time data acquisition and Bluetooth transmission to a smartphone for 7-hydroxycoumarin (7-HC) detection. The GCDs@BP nanocomposite was synthesized via a green self-assembly approach using aqueous-phase processing. Electrochemical determination of 7-HC using the GCDs@BP/SPE sensor demonstrated high sensitivity, a broad linear detection range (0.2–1000 µM), and a low detection limit of 51.3 nM. The synergistic enhancements in sensing performance are attributed to: (1) the formation of interfacial P–C and P–O–C bonds, as confirmed by XPS, which facilitates efficient charge transfer and enhance electrocatalytic activity, (2) the uniform dispersion of GCDs within the BP matrix, revealed by HRTEM and Q-t curves, which increases the effective surface area and provides abundant adsorption sites for 7-HC; and (3) the suppression of phosphorus atomic vibrations, evidenced by Raman peak redshift, indicating strong interfacial coupling that improves structural stability. The proposed sensor was successfully applied to the determination of 7-HC in traditional Chinese medicines, including Zu Shi Ma and Shu Gan He Wei pills, with satisfactory recovery and reproducibility.

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Traditional colorimetric pH strips rely on subjective visual interpretation, while camera specifications and lighting variability often influence smartphone-based systems. We developed a compact, machine learning (ML)-enhanced pH sensing platform combining a custom ESP32-S3 device with controlled LED illumination and a mobile application. The system utilizes a 787-sample dataset spanning pH 0-14, extracting 45 statistical features from the red-green-blue (RGB) channels, hue-saturation-value (HSV) channels, and CIELAB color spaces. An AutoML pipeline was used to select an ExtraTreesRegressor model, achieving an (R^2) value of 0.967 and outperforming traditional RGB-based methods ((R^2) = 0.618). The integrated Android application enables real-time, offline pH prediction via Wi-Fi communication. This fully embedded, end-to-end platform eliminates dependency on smartphone cameras and illumination while maintaining high accuracy across the full pH range, making it well-suited for portable pH monitoring in resource-limited settings.