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

In this paper, bimetallic CuFe Prussian blue analogue (CuFe PBA) was discovered to have oxidase-like activity. Luminol can be oxidized under alkaline conditions without adding other oxidants. The chemiluminescence (CL) intensity produced is more than 1000 times that of the original luminol-NaOH system. Thus, a novel luminol-NaOH-CuFe PBA CL sensor was constructed. The CL intensity of the system would drastically decrease with the addition of uric acid (UA), it served as the foundation for the creation of an enzyme-free CL sensor for the determination of UA. The CL signal intensity of the system showed a linear connection with the square of the UA concentration in the range of 0.25 to 0.45 mmol·L^-1, and the limits of detection was 0.10 mmol·L^-1. This system could be used to construct an efficient CL sensor for the detection of UA in human serum.

Histamine plays a crucial role in regulating various physiological functions and is significantly involved in the development of allergic rhinitis. Accurately measuring histamine levels in nasal secretions can serve as a specific indicator for studying mast cell activation and diagnosing allergic reactions. However, the controversy surrounding histamine levels in nasal secretions during allergenic stimulation suggests potential inaccuracies and imprecision in the analytical methods used, as well as the presence of substances that may interfere with the determination of histamine. In this study, a sensitive and selective spectrofluorometric method was developed using carbon quantum dots (CQDs) derived from beetroot slices, which are non-toxic and eco-friendly materials. These CQDs were functionalized with histamine tetra phenyl borate to determine histamine levels in nasal secretions. Various characterization techniques were employed to confirm the successful synthesis and functionalization of the CQDs. The functionalized CQDs demonstrated enhanced fluorescence and selective interaction with histamine, leading to concentration-dependent fluorescence quenching. The developed method was successfully utilized to compare histamine levels in nasal secretions of healthy individuals and patients with allergic rhinitis. The results showed that the histamine level was significantly higher in patients with allergic rhinitis than in healthy individuals, suggesting a potential association between allergic rhinitis and histamine, (normal vs. patient: 350 ± 20 ng/mL vs. 2520 ± 37 ng/mL, p < 0.05). Furthermore, the proposed spectrofluorometric method exhibited improved linearity range, dynamic range, and detection limit compared to a previously reported spectrophotometric method.

In this study, the ditriphenylamine Indole-BODIPY photosensitizer T₂BDP-lyso was synthesized for near-infrared photodynamic therapy and two-photon fluorescence imaging. The photosensitizer T₂BDP-lyso exhibits absorption above 700 nm and emission above 800 nm, respectively. Theoretical calculations show the energy gap from the excited state S₁ to the excited state T₂ is 0.14 eV, which indicated that the photosensitizer T₂BDP-lyso could reach the triplet state by intersystem crossing from the singlet state. Under NIR light, the singlet oxygen yield of photosensitizer T₂BDP-lyso was calculated to be 0.64 in CH₂Cl₂. The photosensitizer T₂BDP-lyso can effectively produce reactive oxygen species in A549 cells and zebrafish under 660 nm light for 5 min. The photosensitizer T₂BDP-lyso exhibited lower dark toxicity and higher phototoxicity (IC₅₀ = 1.49 μM), as well as lysosomal targeting ability (Pearson coefficient = 0.89). In the AO/EB double staining assay simulating photodynamic therapy at the cellular level, 3 μM of T₂BDP-lyso light for 10 min was effective in killing cancer cells. Moreover, the photosensitizer T₂BDP-lyso has a large two-photon absorption cross section at 1050 nm, which was calculated to be 138.7 GM in THF by Z-scan method, and two-photon fluorescence imaging was performed in zebrafish. The above results indicate the potential application of the photosensitizer T₂BDP-lyso in near-infrared photodynamic therapy and two-photon fluorescence imaging.

Through this contribution, we aim to highlight the structural stability of low dimensional YN structures ranging from the 3D bulk to the 2D square and hexagonal monolayers and their corresponding 1D zigzag single walled nanotubes. For all arrangements, geometry optimization is achieved at the DFT/B3LYP level of theory using a Gaussian basis set. Then, the coupled perturbed Kohn-Sham and Hartree-Fock (CPKS/HF) computational approach is used to simulate Raman and IR spectrum. Rolling, cohesive and relaxation energies, electronic and vibrational contributions to the polarizability and equilibrium lattice parameters are also reported. Insights into their structural stability are provided by combining optimized parameters and vibrational phonon spectra. For the optimized 3D bulks, 2D monolayers and 1D square nanotubes, no imaginary frequency has been recorded in their vibrational spectra which reveals a dynamic stability. Likewise, imaginary frequencies appeared only for relatively large YN (n,0) single walled hexagonal nanotubes (n > 6) indicating that the optimized structures are not a real global minimum and implying a dynamic instability. A scaning mode procedure along the largest imaginary vibrational mode has been adopted to obtain the equilibrium geometry of (22,0) YN hexagonal nanotube. Therefore, it must be emphasized that the obtained potential energy surface presents two minima between a saddle point. These minima corresponds to a stable structures slightly distorted compared to the initial one. The absence of imaginary phonon frequencies in the Raman and IR spectra of the optimized (22,0) YN hexagonal nanotube confirms its structural stability.

Oxytetracycline hydrochloride (OTC) is a commonly used over-the-counter antibiotic, valued for its potent antibacterial properties. However, the inappropriate and excessive use of OTC can result in the accumulation of the drug in both the environment and human body, causing significant harm to ecosystems and human health. Therefore, the development of a fast and sensitive method for detecting OTC is of great significance. Lanthanide metal-organic frameworks (LnMOFs) can effectively excite lanthanide metals to emit long-lifetime, narrow and stable fluorescence based on the antenna effect, but their application in fluorescence sensing is rarely reported. In this work, a strongly fluorescent material Tb-MOF was synthesized by a facile solvothermal method using 1,2,4,5-phenylenetetracarboxylic acid (H₄btec) and 1,10-phenanthroline (1,10-phen) as organic ligands and lanthanide metal Tb as the luminescent center. Tb-MOF is a stable material in water and shows excellent linearity with OTC in the concentration range of 0 ∼ 70 μM, with low detection limit (0.12 μM) and luminescence color transition from bright green to dark green during the detection process. X-ray diffraction, UV-vis absorption and fluorescence lifetime analyses revealed that the fluorescence quenching of Tb-MOF by OTC is caused by the inner filter effect in static quenching. Test strips for OTC detection were successfully prepared using Tb-MOF. These strips are not only low cost and easy to prepare but can also be used as portable sensing devices that can be easily distinguished by the naked eye during OTC testing. This study not only presents a fluorescent probe for the detection of OTC in water but also offers a practical method for converting fluorescent luminescent materials into functional devices for OTC detection.

Carbon dots have demonstrated a great potential as luminescent nanoparticles in energy, drug delivery, sensors, and various biomedical applications as well as environmental pollutants and water analysis. Although, such nanoparticles appear to exhibit low toxicity compared to other semiconductor and metal based luminescent nanomaterials. Today, we know that toxicity of carbon dots (CDs) strongly depends on the protocol of fabrication. The various dopants or heteroatoms have been used to enhance the optical and physicochemical properties. In this work, zinc doped aqueous fluorescent Zn-Cn-CDs have been synthesized from cinnamon by hydrothermal synthesis method. The synthesized Zn-Cn-CDs were confirmed for their physicochemical properties by using various characterization techniques viz. UV-Vis. and spectrofluorometer for optical properties, Fourier transform infrared spectroscopy (FTIR) and XRD, as well as TEM and XPS, was done for morphological and chemical analysis. The successfully synthesized Zn-Cn-CDs showed outstanding optical performance for metal ion sensing applications. The developed heteroatom doped Zn-Cn-CDs as a fluorescent probe exhibited higher selectivity and sensitivity for Cr⁶⁺ and Mn⁷⁺ metal ions. The obtained results showed a better linear range with excellent limit of detection (LOD) 3.97 µg/mL and 2.05 µg/mL for Cr⁶⁺ and Mn⁷⁺ metal ions respectively. The low cost, simple and highly fluorescent probe can be effectively applicable for development of environmental pollutants sensing purposes.

Cadmium is a representative carcinogenic heavy metal. Because of the long biological half-life of cadmium, it is critical to prevent and detect cadmium inflow into the body. In this study, we developed the biomimetic magneto-gold nano-urchin (MGNU)-based surface-enhanced Raman scattering (SERS) chip for ultrasensitive detection of cadmium. The MGNU SERS chip was facilely fabricated using three-dimensional (3D) printed magnetic molds. The 3D printed magnetic molds were designed for contributing to (1) making hydrophobic/hydrophilic areas and (2) magnetic SERS enhancement by attracting the MGNUs. To validate the performance of the MGNU SERS chip, we conducted electromagnetic simulations and measurements of SERS efficiencies. Consequently, we detected cadmium ions up to 1.33 pM in distilled water. Moreover, we succeeded to detect cadmium ions in the real environmental samples up to 2.76 pM in the tap water and 14.21 pM in the human blood plasma, respectively. The MGNU SERS chip is a powerful SERS substrate that can be used in various spectrometer-based sensing platforms.

Soluble solids content (SSC) is one of the most important internal quality attributes of fruit and could be predicted using near-infrared (NIR) spectra and optical properties. Partial least squares regression (PLSR) is a conventional regression method in SSC prediction. In recent years, deep learning methods represented by convolutional neural network (CNN) was suggested to be implied in spectral analysis. However, researchers are inevitably facing problems with regard to the selection of spectral pretreatment methods and the evaluation of the performance of the chosen regression. This study employed PLSR and CNN regression to predict SSC of apple based on the collected diffuse reflectance spectra of intact apple, total reflectance and total transmittance spectra of apple pulp, and the calculated optical property spectra, i.e., absorption coefficient and reduced scattering coefficient spectra of apple pulp. Five different spectral pretreatment methods were exerted on these spectra. Results showed that at a given regression (PLSR or CNN), the built models based on the diffuse reflectance spectra of intact apple had the best SSC prediction, and the built models based on pulp's reduced scattering coefficient spectra had the poorest prediction performance. The best prediction performance was achieved by PLSR models using Savitzky-Golay with multiple scattering correction (R_p = 0.96, RMSEP = 0.54 %) and CNN regressions using Savitzky-Golay with standard normal variational transformation (R_p = 0.95, RMSEP = 0.59 %), respectively. Additionally, when the unknown original spectra were used for modeling, CNN had a better performance compared to PLSR, indicating the outstanding preponderance of CNN in spectral analysis. This study provides an effective reference for the selection of chemometric method based on NIR spectra.

This work studied suspicious and authentic artworks by Brazilian painters Ivan Serpa, Ismael Nery, and Iberê Camargo by XRF, FTIR, OM, and MA-XRF techniques. The studies made it possible to verify that all suspicious artworks are counterfeit artifacts. The analyses were conducted in situ, and different approaches were applied for data treatment. For example, principal component analysis and spectral deconvolution were performed on the XRF data. From these methods, it was possible to verify that the suspect artworks by Ivan Serpa and Iberê Camargo have different materiality than the authentic paintings. Additionally, MA-XRF images did not reveal the presence of a polychrome preparation layer in the suspicious paintings by Ivan Serpa. The suspect artworks from Ismael Nery exhibited a Ca-K/Ti-K ratio that indicates they were created on a low-quality paper support, which is not suitable for paintings. The differences in materials used in the suspicious and authentic artworks are further supported by the FTIR and OM results. In addition to the physicochemical analysis, the paintings were studies graphotechnical examinations, financial evaluations, and artistic analyses that demonstrated they were counterfeit artifacts. The results of the analysis demonstrate how physicochemical techniques can contribute to the forensic investigation of paintings. However, this work highlights the importance of applying distinct treatments to the XRF data in order to accentuate the differences between the suspect and authentic artworks.

In this work, an accurate potential energy curve (PEC) for the ground electronic state of phosphorus mononitride (PN) molecule has been determined from a variationally improved Hulburt-Hirschfelder (VIHH) oscillator model in conjunction with the experimental spectral constants (D_e,ω_e,ω_ex_e,B_e,α_e,r_e). We have numerically solved the Schrödinger equation for the VIHH potential using the LEVEL program, obtaining the pure vibrational spectrum that converges to the dissociation limit. In addition, the partition functions of PN molecule are calculated using the full rovibrational energies. Ultimately, thermodynamic properties like molar heat capacity, entropy, enthalpy, and Gibbs free energy were calculated for the PN molecule and show good agreement with those data from the NIST (National Institute of Standards and Technology) database.