Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy最新文献

The sensitive and accurate detection of FEN1 and T4 PNK activities is of vital significance for the early diagnosis and therapeutic monitoring of cancer. Herein, we constructed a DNA tetrahedron-radiated nanonetwork (DTRN) based on multi-stage rolling circle amplifications (RCAs) for sensitive and dual-mode detection of FEN1 and T4 PNK activities. Specifically, the design included a DNA tetrahedron nanoprobe with four first-stage trigger sequences for first-stage RCAs, recognition elements and circular substrates serving as RCA templates, as well as a hairpin probe with multi-stage trigger sequence for multi-stage RCAs. Initially, FEN1 or T4 PNK-specific recognition events initiated ligation reactions, which induced the first-stage trigger sequences to activate first-stage RCAs, synthesizing long single-stranded DNAs with repetitive sequences. By recognizing these repetitive sequences, the hairpin probes initiated multi-site second-stage RCAs and further activated multi-stage RCAs. Eventually, numerous multi-stage trigger sequences extended simultaneously from different sites, generating a nanonetwork centered on the DNA tetrahedron, while concomitantly producing fluorescent and UV-vis absorption signals for quantification. The DTRN system achieved exponential enhancement in amplification efficiency through multi-stage RCAs on the DNA tetrahedron, improving detection sensitivity. The detection limit were as low as 4.58 × 10^-3 U mL^-1 of FEN1 and 5.76 × 10^-4 U mL^-1 of T4 PNK in fluorescent mode, 2.45 × 10^-2 U mL^-1 of FEN1 and 3.75 × 10^-3 U mL^-1 of T4 PNK in colorimetric mode. Moreover, the dual-mode detection facilitated mutual verification and complementation, enhancing detection accuracy. Furthermore, the successful detection of dual enzyme activities in cellular extracts confirmed that the DTRN system is a highly potent detection tool.

This investigation elucidates the crystal structure, thermal behavior, and vibrational dynamics of L-tyrosine hydroiodide (LTHI), comparing it with its chloride (LTHCl) and bromide (LTHBr) analogue. Single-crystal X-ray diffraction analysis confirmed the monoclinic (P2₁) symmetry of LTHI, featuring asymmetric units interconnected via OH⋯O hydrogen bonds and NH⋯I contact. Differential scanning calorimetry (DSC) demonstrated enhanced thermal stability for LTHI (decomposition at 591 K), attributed to the large ionic radius of I^-, which elongates NH⋯I bonds (3.54 Å) and facilitates stabilizing CH⋯π contacts. Raman spectroscopy data revealed systematic low-frequency shifts (102 cm^-1 for LTHI) with increasing halide size, indicating reduced lattice rigidity due to iodide's polarizability. Hirshfeld surface analysis enabled quantification of the intermolecular interactions, highlighting the key contributions from H⋯I/H⋯I (26.3%) and H⋯C/C⋯H (13.6%) contacts. Electronic structure calculations correlated iodide's polarizability with reduced chemical hardness (η = 2.83 eV) and reversible vibrational responses during heating cycles. These insights highlight halogen-dependent stability mechanisms in amino acid salts for biomaterial design.

The optical vibrational modes of natural monoclinic ludlamite crystal, [Formula: see text] , were investigated by polarized Raman and infrared-reflectivity spectroscopies. High-quality single crystals from a granitic pegmatite at the Boa Vista Mine (Brazil) were selected for this study. Backscattering polarized micro-Raman spectra were acquired on the main {001} cleavage face of the crystal using four different scattering geometries, with parallel and crossed polarizations relative to the crystallographic a and b axes. Near-normal infrared-reflectivity spectra were collected using a Cassegrain microscope on the {001} and {100} cleavage faces, with polarizers aligned along the crystallographic a, b, or c axes. The infrared spectra were analyzed within the Lorentz oscillator model, allowing the determination of the infrared dielectric function projections along specific crystallographic directions. In summary, all 36 Raman-active modes predicted by group theory for the anhydrous framework of ludlamite (18A_g and 18B_g) and 35 infrared-active phonons (18A_u + 17B_u) were identified and assigned (2A_u and 2B_u modes were missing). Additional bands were identified in Raman and infrared spectra, a two-mode behavior of cation lattice modes, attributed to the partial substitution of Fe²⁺ by Mg²⁺ in the natural crystal, as well as some bands associated with hydrogenated phosphate species. The calculated infrared dielectric functions, along with the static and high frequency (background) dielectric constants, were analyzed and found to be consistent with the expected values for ludlamite.

SO₂ derivatives (SO₃^2-/HSO₃^-) are essential intermediates in plant sulfur metabolism and are extensively used as preservatives and antioxidants in the food industry, highlighting the urgent need for efficient, on-spot methods for their accurate quantification. Herein, we present GL, a rationally designed dual-mode probe that combines colorimetric and ratiometric near-infrared (NIR) fluorescence responses for SO₃^2- detection. GL exhibits strong intrinsic NIR fluorescence and, upon reaction with SO₃^2- via a specific nucleophilic addition mechanism, produces both a visible color change and a ratiometric fluorescence shift. This dual-signal strategy enhances specificity, reduces background interference, and enables reliable cross-validation. The versatility of GL was demonstrated through diverse applications, including bioimaging SO₃^2- in living cells and zebrafish, monitoring SO₃^2- accumulation in Brassica chinensis leaves and stems under varying sulfur conditions, and, when integrated with a self-made portable sensing system, achieving on-spot quantitative detection of SO₃^2- in real food samples.

Detecting abnormal lipid levels and timely intervention have great potential for diagnosis and treatment of non-alcoholic fatty liver disease (NAFLD). Herein, a novel molecular electron density engineering strategy for synergistically strengthened lipid droplets (LDs) fluorescence probes based on the chalcone skeleton is presented for simultaneous fluorescence diagnosis and drug evaluation of NAFLD. Specifically, a series of novel chalcone derivatives (C1-C7) with controlled intrinsic electron density distribution are rationally fabricated via introducing various push-pull electronic groups into triphenylamine-fused chalcones. Notably, the optical properties including polarity sensibility, Stokes shift, fluorescence emission, photostability, and aggregation-induced emission (AIE) characteristics are all synergistically boosted upon transforming from D-π-A-π-D to D-π-A-π-A architectures. C2 is identified as the optimal probe for LDs-targeted dynamic high-fidelity fluorescence monitoring in live cells, revealing a novel LDs motion pattern termed "Sequential Separation". Further, C2 permits multiscale fluorescence imaging diagnosis of NAFLD in vitro/vivo. Moreover, two LDs-based drug evaluation protocols utilizing C2 for NAFLD intervention are first established, and sesamol is identified as a potential NAFLD therapeutic agent through these assays. Overall, this work not only provides a rational design strategy and novel probe toolbox for the early diagnosis of NAFLD, but also develops pioneering drug screening methodologies for exploiting potential NAFLD therapeutic drugs.

The deposition of heavy metal ions and pesticides has presented a significant threat to ecological systems and human health. Consequently, the development of rapid and highly efficient detection technologies is of critical importance. In this work, a novel fluorescent probe, N'-(2-butyl-1,3-dioxo-2,3-dihydro-1H-benzo[de]isoquinolin-6-yl)benzo[b]thiophene-2-carbohydrazide (NDBC), was successfully designed and synthesized by incorporating naphthimide and acylhydrazine. The synthesized NDBC enables continuous detection of Hg²⁺ and nitenpyram based on a "turn-off-on" fluorescence signal response. When Hg²⁺ was added to the NDBC solution, the system showed a pronounced quenching phenomenon, with a detection limit of 0.12 μM. The NDBC was effectively employed for detecting environmental samples, including tap water, Songhua River water, and Nejiang River water, achieving recovery rates ranging from 98.15% to 102.13% and a relative standard deviation (RSD) between 1.03% and 4.47%. Upon introducing nitenpyram to the NDBC-Hg²⁺ complex, the fluorescence returned to its original level, achieving a detection limit of 0.31 μM. The system was effectively employed for detecting environmental samples, including tap water, Songhua River water, and Nejiang River water, achieving recovery rates ranging from 95.58% to 101.15% and a relative standard deviation (RSD) between 0.83% and 4.59%. Additionally, fluorescence biological imaging of Hg²⁺ and nitenpyram in living cells and zebrafish was successfully achieved. This work develops a new approach for the rapid detection of Hg²⁺ and nitenpyram, offering promise for application in both environmental and biological sample analysis.

Simple and effective monitoring of intracellular reactive oxygen species (ROS) variations caused by external oxidative stresses is very important in the biomedical field. However, there are many challenges in monitoring the ROS variations. It should consider both the entire cell population and individual cell, and whether it has the ability to monitor dynamically for a long time. In addition, a very important consideration is the generation of additional ROS caused by the monitoring process. Around these perspectives, in this study, an alloy-type probe displaying both circular dichroism (CD) and Raman signals is precisely designed and prepared. When cells are subjected to oxidative stress, the silver-element helical stripes on the surface of the intracellular alloy-type probe are etched by the generated ROS, resulting in a simultaneous decrease in the CD and Raman signals from the probe. The variation of ROS in macroscopic cell populations and individual cell can be monitored by CD and Raman, respectively. It is noteworthy that the monitoring process based on the present probe completely avoids the generation of additional ROS, which may be caused by the excitation light. The strategy proposed in this research improves the methods for monitoring intracellular ROS variation and provides a guiding framework for the design of probe materials in the future.

Nanozymes have been widely applied in the field of biosensing due to their enzyme-like catalytic activity and unique properties of nanomaterials. The activity of nanozymes is a key factor influencing sensor performance including detection sensitivity and analysis time. Therefore, developing new strategies to effectively improve the catalytic performance of the nanozyme is highly anticipated. This study takes Co₃O₄ nanozyme as an example, using low-cost and enzyme-free ovalbumin (OVA) as the template, generates additional pore structures within metal-organic frameworks, thereby increasing surface area and accelerating mass transfer rates. Meanwhile, OVA serves as both the nitrogen and carbon sources to promote electron transfer and further regulate the activity of nanozyme. Based on the above strategies, a N/C-Co₃O₄ nanozyme with efficient oxidase-like activity was successfully synthesized and applied in colorimetric detection of magnesium ascorbyl phosphate. The developed sensing system exhibited linear response across concentrations ranging from 0.50 to 70 μM, with calculated detection limit of 0.36 μM. These results demonstrate an innovative approach for regulating nanozyme activity through the integration of multiple methodological strategies.

Raman spectroscopy is limited by weak scattering and inefficient photon collection, especially for rough and heterogeneous samples. Here, a multi-probe detection strategy is proposed to simultaneously acquire Raman signals from multiple angles, thereby enhancing the Raman signal and suppressing signal fluctuations. Compared with conventional single-probe detection, the multi-probe configuration exhibits higher signal intensity and improved stability, with a more pronounced enhancement observed for powder samples. Electromagnetic simulations reveal that multi-directional detection effectively collects Raman photons that are otherwise lost in the single-probe detection geometries. As a practical demonstration, a signal enhancement of up to 63% is observed for melamine powder samples. The multi-probe scheme extends the SERS detection limit of 4-aminothiophenol (ATP) on rough substrates to 10^-7 mol/L. At this concentration, the relative standard deviation (RSD) reduction is over 57%. This work provides a simple and effective approach for improving sensitivity and reliability in Raman spectroscopy.

Accurate and timely identification of potentially necrotic intestinal segments during surgery is critical for surgical decision-making. However, existing classification methods heavily rely on labeled data or struggle to capture early subtle abnormal features, thereby limiting their accuracy and generalizability in clinical applications. This study aims to achieve sensitive detection of potentially necrotic intestinal segments through an unsupervised one-class classification method based on autoencoder (AE) residuals. The AE was trained using readily available multispectral data from the normal small intestine to construct residuals that amplify abnormal spectral differences. The residual features were used as input for three unsupervised one-class classification algorithms, namely Local Outlier Factor, Isolation Forest and Minimum Covariance Determinant (MCD) for detection. Validation data were collected from rabbit models under different occlusion durations. The construction of residuals significantly improved the performance of all classifiers. In the potentially necrotic phase at 10 min of occlusion, the overall accuracy of the algorithms was steadily improved at about 80%, especially the sensitivity of MCD jumped from 26.5% to 80.7%, ensuring high detection rates from the outset. When the occlusion duration was extended, the sensitivity of all algorithms showed a positive correlation, consistent with the object physiological patterns. Final visualization results confirmed that residual features improved classification performance and preserved spatial continuity. This approach shows promise for early anomaly detection in other medical imaging applications.