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

To achieve rapid, non-destructive detection of food quality indicators, this study introduces a novel method that combines near-infrared (NIR) spectroscopy with the Extreme learning machine (ELM) model. Eight spectral preprocessing methods and three wavelength selection algorithms were evaluated for predicting total ginsenoside content (TGC) and protein content (PC), along with a comparative analysis of the ELM model's performance against support vector regression and random forest. Results showed that Savitzky-Golay smoothing with standard normal variate was the best preprocessing method, K-means clustering provided the optimal wavelength selection algorithm, and the ELM model demonstrated the best performance. Specifically, the ELM based on K-means method achieved optimal results: R² of 0.9431, RMSE of 0.2933 mg/g, rRMSE of 0.0824, RPD of 4.2386, and P-time of 4 × 10^-7 s for TGC; and R² of 0.9764, RMSE of 4.1361 mg/g, rRMSE of 0.0337, RPD of 6.1295, and P-time of 2 × 10^-7 s for PC. In summary, combining NIR spectroscopy with the ELM model and clustering-based wavelength selection algorithm offers a reliable and practical solution for rapid, non-destructive, and accurate detection of food quality indicators.

Rationale: Procaine HCl (PrHCl), a protic ionic liquid (PIL), exhibits intricate relaxation due to ionic and neutral species interactions. However, its glass-forming ability is limited. To overcome these limitations, this study explores the synthesis of a novel PIL, PrHIb, by replacing Cl^- with the bulky, asymmetric ibuprofen anion. This modification is expected to introduce steric hindrance, restrict molecular mobility, and decouple relaxation processes, thereby enhancing thermal stability, glass-forming ability, and pharmaceutical functionality.

Aim: To synthesize and characterize a novel protic ionic liquid, PrHIb, with a focus on relaxation dynamics, glass-forming ability, and dual therapeutic potential.

Method: PrHIb synthesis was validated by density functional theory (DFT), Fourier Transform Infrared Spectrscopy (FTIR), and Fourier Transform Raman Spectroscopy (FT-RS). The antibacterial and anti-inflammatory properties of PrHIb were evaluated. Thermal and molecular dynamics were studied by differential scanning calorimetry (DSC) and broadband dielectric spectroscopy (BDS). Molecular mobility was assessed to decipher the decoupling of ionic and neutral molecules. The polymer matrices were explored to enhance performance and applicability by restricting molecular mobility.

Results and discussion: DFT confirmed PrHIb formation as endothermic and non-spontaneous under standard conditions with positive enthalpy (∆H = -3.88× 10⁵ kcal/mol) and Gibbs free energy (∆G = -3.88× 10⁵ kcal/mol), while negative entropy (∆S = -56.43 cal/molK) reflects reduced system disorder. FTIR and FT-RS validated the incorporation of functional groups from procaine and ibuprofen. PrHIb exhibited enhanced antimicrobial efficacy against E. coli (62 %) and Pseudomonas (80 %) compared to PrHCl and retained strong anti-inflammatory activity (95 %). DSC and BDS studies confirmed glass-forming behavior, with a T_g of 266 K. Replacement of Cl^- with Ibu^- led to decoupled relaxation and the lack of secondary relaxation. Two distinct relaxations in M″(ω) were attributed to ionic conductivity and structural relaxation. All data were fit the Havriliak-Negami equation. Vogel-Fulcher-Tammann (VFT) showed high fragility (m = 102), indicating sharp viscosity changes near T_g. polyvinylpyrrolidone (PVP) confinement reduced fragility (m = 36), suppressed ionic hopping, and improved stability with a T_g of ∼269 K.

Conclusion: Replacing Cl^- with bulky, asymmetric Ib^- in PrHIb restricts molecular mobility, leading to decoupled relaxation processes and enhanced dynamic heterogeneity. Confinement in a PVP matrix further stabilizes PrHIb by reducing fragility and improving its glass-forming ability. These features, along with dual antimicrobial and anti-inflammatory activity, h

Kaempferol (3,4',5,7-tetrahydroxyflavone, KMP) and curcumin (diferuloylmethane, CUR) are naturally occurring polyphenolic compounds with broad therapeutic potential, including anticancer, antioxidant, and anti-inflammatory properties. Among their molecular targets, DNA plays a central role, particularly through interactions with non-canonical DNA structures such as G-quadruplexes (G₄) and i-motifs (C₄), which form in guanine- and cytosine-rich genomic regions, respectively. These structures regulate telomere maintenance, gene expression, and genomic stability, making them attractive drug targets. In this study, we investigate the binding behavior of KMP and CUR with G₄, C₄, and duplex calf thymus DNA (calf thymus (CT)-DNA) using an integrated spectroscopic and computational approach. Circular dichroism, UV-visible absorption, and fluorescence spectroscopy were used to monitor ligand-induced structural and photophysical changes. CUR exhibited pronounced solvatochromism, with emission maxima shifting according to solvent polarity and DNA topology and showed the strongest fluorescence enhancement in G₄ DNA. KMP displayed excited state intramolecular proton transfer (ESIPT), with the highest tautomeric emission observed in G₄ structures. However, G₄ also facilitated ground-state anion formation at the 3-OH group of KMP, which suppressed ESIPT by interfering with intramolecular hydrogen bonding between C(4) = O and 3-OH. ESIPT was least prominent in C₄, and moderate in duplex DNA, where anion formation was less favored. Displacement assays using ethidium bromide (EtBr) provided functional insight into the competitive binding dynamics, confirming groove and loop binding for both ligands in G₄ and C₄ DNA, while KMP also exhibited intercalative binding in duplex DNA. Molecular docking and molecular dynamics simulations corroborated these findings, revealing stable ligand-DNA complexes and specific interaction modes. This comprehensive approach highlights CUR as a polarity-sensitive reporter and KMP as a thermally and structurally responsive ESIPT fluorophore. Together, they represent promising tools for probing DNA topology and developing targeted molecular diagnostics or therapeutic strategies centered on nucleic acid structure recognition.

Traumatic brain injury (TBI) is a serious clinical and social problem. Millions of TBI cases, that require hospitalization and consequently burden social security systems, are reported each year. Analysis of the time course of changes that occur in the brain after primary injury may help indicate therapeutic goals and treatment directions that will minimize severe secondary effects of TBI. Existing animal models simulating the development of TBI in human are divided into two main groups, namely into diffuse and local models. Diffuse injury models are ideal for studying concussions and long-term effects of TBI, as they replicate global changes occurring in brain. Local injury models excel in examining focal brain damage and testing region-specific therapies, they also offer greater control and reproducibility. In our study local induction of TBI enabled better control of the extent of the damage and thus reduced the number of animals needed for the experiment. As part of the work, Fourier transform infrared microspectroscopy and complementary Raman microscopy were used to track the time course of biochemical changes that occur in the rat cerebral cortex as a result of its local mechanical damage. Comparative studies, carried out for the injury site and microscopically unaffected area of the cerebral cortex, indicated some anomalies in the accumulation and structure of organic compounds, including a reduction of the level of cholesterol/cholesterol esters (approx. 30 % in first two examined periods after TBI) and the compounds containing phosphate groups (approx. 25 %), as well as the conformational changes of proteins and lipids in the injury site comparing to unchanged cortex tissue. The comparison of the glial scar development in male and female rats showed only a very subtle differences between sexes. Among them it is necessary to mention the diminished unsaturation degree of lipids within the scar in case of female rats that was not found in males. The obtained results substantiated that vibrational microspectroscopy methods represent powerful, non-destructive tool of high-resolution biomolecular analysis of brain tissue. These techniques enable the identification of biochemical alterations linked to glial scarring following TBI, allow for the monitoring of the dynamics of this process, and provide insights into the sex-dependence of the recorded anomalies. This knowledge could prove instrumental in identifying potential diagnostic and prognostic biomarkers of TBI, as well as in the development of new therapeutic strategies for managing this condition.

Carbonized polymer dots (CPDs), a new nanofluorescent materials inheriting the advantages of CDs, have been widely studied for their excellent physicochemical stability and tunable fluorescence properties, and have extensive application in the fields of optoelectronic devices and environmental monitoring. In this study, nitrogen-doped CPDs (CMC-M-CPDs) were synthesized via hydrothermal reaction using carboxymethyl cellulose (CMC) and melamine (M), which allowed N doping to improve the luminescence of CPDs through cross-linking and reduction of the energy gap. Due to the excitation-dependent, the luminescence wavelength of CPDs can be tuned, so these CPDs exhibit two optimal emission centers in the fluorescence spectra, which originate from the carbon core and the surface, respectively. A significant quenching effect on the luminescence of CMC-M-CPDs at 457 nm and 515 nm was exhibited due to static quenching of Cr(VI). Therefore, dual-channel fluorescence detection of Cr(VI) can be achieved, allowing detection using both excitation wavelengths to be carried out concurrently and mutually verified in complex environments. This improves the accuracy of detection, with limits of detection (LOD) of 60.15 nM and 93.95 nM, respectively. The CMC-M-CPDs demonstrate excellent selectivity and anti-interference in the detection of Cr(VI), with a quenching response occurring within 1 s. This dual-channel fluorescent probe can also be applied for sensitive detection in tap water and Songhua River water. Furthermore, the fluorescence of quenched CPDs can be restored by adding ascorbic acid (AA), achieving a maximum recovery efficiency of 96.6 %.

Polarity, viscosity and peroxynitrite (ONOO^-) are key factors in determining mitochondrial function and activity, and real-time monitoring of these parameters is important for gaining insight into the physiological mechanisms involved. In this study, we developed a new multifunctional fluorescent probe CNB-2 for monitoring mitochondrial polarity, viscosity, and ONOO^- level fluctuations. CNB-2 demonstrated robust responses to polarity and viscosity, with its fluorescence intensity exhibiting a strong linear correlation to the logarithm of polarity parameters and viscosity, increasing significantly as these parameters rise. Notably, for ONOO^- detection, CNB-2 is characterized by rapid response, high selectivity, a low detection limit (51.3 nM), and a large Stokes shift (130 nm). Moreover, CNB-2 can be used for live cell imaging of mitochondrial polarity, viscosity, and ONOO^-, as well as monitoring of changes in ONOO^- concentration in real-time during ferroptosis. Therefore, the prepared probe CNB-2 provides a reliable tool for better understanding the mitochondrial microenvironment and a new way for diagnosing ferroptosis-related diseases.

Methylene blue (MB), as a phenothiazine dye, causes a harmful damage to health and receives increasingly more environmental concern. Herein, the batch experiments for MB biosorption and biotransformation by Haematococcus pluvialis were carried out to evaluate the optimal parameters of MB removal. In this work, we found that the maximum removal efficiency was attained when MB was at the initial concentration of 5 mg/L. Meanwhile, the cellular numbers and pigments decreased dramatically with the rising content of MB. Furthermore, synchrotron-FTIR microscopic imaging is employed here to investigate the interaction between MB dye and algal cells by the measurement of the various vital changes of cellular components involving in the bioremediation of the hazardous dye, which indicated that MB dye as a photosensitizer can trigger the algal transformation from vegetative cells into red cysts by introducing oxidative stress. Accordingly, the dye removal efficiency can be sharply enhanced by the transformed algal cells for the accumulation of astaxanthin or carotenoids. In addition, the FTIR spectroscopy combined with PCA algorithm was further utilized to discriminate various algal status based on their spectral features. As a result, it demonstrates that microscopic imaging and FTIR spectroscopy is a powerful and useful tool to elucidate underlying mechanisms of dye removal by algal cells at high spatial resolution and to evaluate cellular physiological characteristics through multivariate statistical analysis, and it even provides a novel and effective strategy to rapidly screen the potential microalgae for the removal of recalcitrant dyes from wastewater.

Phosphate pollution leads to the deterioration of water quality, posing a serious threat to human health. Tetracycline hydrochloride (TC), a class of broad-spectrum bacteriostatic agents, has garnered attention due to its extensive use and potential toxicity. Therefore, developing a highly selective and sensitive fluorescent probe for the detection of phosphates and TC is of significant importance. Herein, to enhance the conversion and utilization of high-value biomass waste, biomass-derived carbon dots (LZ-NCDs) emitting green fluorescence with a quantum yield of 44 % were synthesized in a one-step hydrothermal process using chestnut shell biomass waste as a carbon source and nitrogen doping technology. Based on the dynamic quenching mechanism, a highly sensitive method for effectively identifying PO₄^3- using LZ-NCDs fluorescence probe was constructed, with a linear range of 0.1-10 µmol/L and a detection limit of 43.0 nmol/L. A quenched fluorescent probe, LZ-NCDs for the determination of TC, was fabricated through the synergistic effects of inner filter effect and static quenching, exhibiting a linear range from 0.05 to 10 µmol/L with a detection limit of 16.8 nmol/L. The successful determination of PO₄^3- and TC in actual samples was achieved. The two different quenching mechanisms indicate that LZ-NCDs are expected to become potential sensing materials for the real-time monitoring of PO₄^3- and TC in organisms and food, which is very important for our health.

The research aimed to develop of a thiabendazole-derived dual metal sensing probe (TBZT) for the selective detection of metal ions and to explore its metal complexes in reducing environmental pollutants like nitro-phenol and dyes. Absorption and emission based studies predicted the selectivity and sensitivity of TBZT towards Ni(II) and Co(II) ions which was further validated by ¹HNMR, Mass, FT-IR, DFT, Docking, electrochemical, TGA studies and vibrating sample magnetometer analysis techniques. Limit of detection (LOD) values were calculated as 2 × 10^-10 M and 4.17 × 10^-8 M for Ni(II) metal ion in emission and absorption based techniques respectively and 2.8 × 10^-9 M and 4.5 × 10^-6 M for Co(II). EDTA based Reversible binding behaviour suggested its potential for constructing molecular logic gates. Catalytic studies of metal complexes of TBZT with these metals demonstrated TBZT-Co(II) superior activity in reducing nitro-phenol, rhodamine B and methyl red. Real sample analysis validated its capability for the environmental monitoring of these metal ions. This emphasized its potential application in metal ion detection and catalysis.

The analysis of Raman and Infrared (IR) phonons in monolayered tetragonal (Sr, Ba)₂HfO₄ compounds, which exhibit D₁₇^4h symmetry and belong to the I4/mmm phase of space group 139 with Z = 2, has been conducted using normal coordinates. The Sr₂HfO₄ and Ba₂HfO₄ compounds are the first members of the Ruddlesden-Popper (RP) series denoted as (Sr, Ba)_n+1HfO_3n+1 with n = 1. Nine Short-Range Force Constants (SRFC) have been included in theoretical calculations to analyze the optical phonons of Sr₂HfO₄ and Ba₂HfO₄ compounds within the I4/mmm phase. The assignments of optical vibrational modes in (Sr, Ba)₂HfO₄ compounds have been determined using Wilson's GF-Matrix Method and cross-referenced with data obtained from compounds sharing similar structural characteristics. The analysis also involved studying how the exchange of cation-A (A = Sr, Ba) impacts the lattice dynamics of the isostructural compounds A₂HfO₄ (A = Sr, Ba) in monolayered tetragonal structures. In this analysis, a comparison has been made between the vibrational modes at the Zone Center, the force constants, and bond lengths to assess the influence of the cation exchange. Furthermore, for each normal mode in the Ruddlesden-Popper phase (Sr, Ba)₂HfO₄, the examination of Potential Energy Distribution (PED) sheds light on the significant impact exerted by Short-Range Force Constants on the calculated vibrational modes, providing a deeper understanding of their behavior and interactions.