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

Hollow polymer microspheres (HPMs) were synthesized, which were then hydrolyzed in aqueous ammonia to produce carboxyl (-COOH) groups on their surface. L-phenylalanine (L-Phe) was grafted to the hydrolyzed HPMs (H-HPMs) through amidation reactions, endowing the H-HPMs with chirality. The resultant chiral HPMs (C-HPMs) were used for the chiral discrimination of tryptophan (Trp) isomers. Due to the same rotatorydirection of L-Phe and L-Trp, the C-HPMs showed greatly higher selectivity toward L-Trp than its isomer. After being adsorbed by the C-HPMs, the absorbance of the residual L-Trp is significantly lower than that of the residual D-Trp, and thus spectroscopic chiral discrimination of the Trp isomers was successfully achieved. The Trp isomers were also discriminated by the chiral solid polymer microspheres (C-SPMs), while the difference in the absorbance of the residual L-Trp and D-Trp is remarkably smaller than that obtained by the C-HPMs. The outstanding discrimination capability of the C-HPMs might be ascribed to their high surface permeability resulted from their unique hollow structure.

This study explores a novel method for detecting neonicotinoid insecticides, imidacloprid (IMD) and dinotefuran (DNT), in water using terbium (Tb³⁺) ions photo probe. The optimal excitation and emission wavelengths for Tb³⁺ luminescence were identified at 310 nm and 545 nm, respectively. The influence of pH and solvent on Tb-complex fluorescence was investigated. Results indicate a significant enhancement of luminescence intensity at pH 6 for IMD in DMF and pH 7.0 for DNT in DMSO. The fluorescence intensity exhibited a linear relationship with IMD and DNT concentrations ranging from 0.1 to 20 µg/mL (R² > 0.99). Limits of quantitation (LOQ) were determined as 0.1 µg/mL for IMD and 0.05 µg/mL for DNT. This newly developed photo probe demonstrates the potential for monitoring photolysis and photocatalytic degradation of these neonicotinoids using TiO₂ as a catalyst under controlled photoreactor conditions. The method offers a promising alternative for rapidly and sensitively detecting these prevalent insecticides in water samples.

The design of novel polymer donors for organic solar cells has been a major research focus for decades, but discovering unique materials remains challenging due to the high cost of experimentation. In this study, machine learning models are employed to predict power conversion efficiency (PCE), Mordred descriptors are used for model training. Among the four machine learning models evaluated, the gradient boosting regressor emerged as the best-performing model. Additionally, a chemical library of polymer donors was generated and analyzed using various measures. 30 donors with highest PCE are selected and their synthetic accessibility is evaluated. Similarity analysis has indicated much resemblance in selected polymer donors.

Metal-organic frameworks (MOFs) have risen to prominence due to their unique structural features, including high porosity and tunable surface chemistry. As nanozymes, the MOFs replicate the catalytic activity of natural enzymes, thereby offering stability under diverse conditions and heightened efficiency. Glutathione (GSH) is a vital intracellular antioxidant and disease biomarker for cancer and neurodegenerative disorders. In this study, the intrinsic-oxidase activity of MIL-88A(Fe) was explored to develop a naked-eye-based colorimetric sensor for the detection of GSH. The 3,3',5,5',-tetramethyl benzidine (TMB) substrate was oxidized by MIL-88A(Fe), leading to the formation ofblue-colored oxidized TMB. The addition of GSH resultsin the reduction of oxidized TMB, causing the blue color to fade and a decrease in absorbance at 652 nm. Under optimal conditions, the developed sensor has a good linear relationship with GSH concentrations ranging from 0-40 μM with a detection limit of 150 nM. The developed methodwas successfully used to determine GSH accurately in real food and pharmaceutical samples. Further, the sensor demonstrated satisfactory performance for smartphone-based GSH detection on a paper-based assay. This work demonstrates the rapid, inexpensive, and ultrasensitive detection of GSH, opening new avenues for additional food quality and pharmaceuticalmonitoring.

Carbon dots were synthesized from fenugreek seeds through a single step hydrothermal method. The method is simple, fast, pleasant to the environment and cheaper. The CDs were characterized by Fourier Transform Infrared (FTIR), UV-visible spectrophotometer, X-ray diffraction (XRD), High Resolution Transmission electron microscopy (HR-TEM), and fluorescence. The CDs obtained were extremely fluorescent. The fluorescent carbon dots exhibited excitation-dependent behavior with the maximum excitation at 372 nm. The interaction of CDs was studied with different selected cations Al³⁺, Ca²⁺, Cd²⁺, Cr³⁺, Co²⁺, Cu²⁺, Cu⁺, Fe²⁺, Fe³⁺, K⁺, Sn⁴⁺, Na⁺, Ni²⁺, Pb²⁺, Mn²⁺, Zn²⁺, Sr²⁺, (NH₄)₆Mo₇O_24, 4H₂O, Cr⁶⁺, Sb³⁺, Ba²⁺, Li⁺, and Mg²⁺. None of the ions studied showed any effect on its fluorescence intensity except Pb²⁺ which decreased its intensity. A direct relationship was found between Pb²⁺ concentrations and quenching of CDs intensity. Detection limit (DL) and quantification limits (QL) were determined as three and ten times of the standard deviation of the blank for ten number of measurements. DL and QL were found in the order 9.345 μM and 31.15 μM respectively. This linear behavior between quenching and Pb²⁺ concentration is useful for analytical purpose.

A simple, low-cost hydrothermal method was employed to synthesize highly fluorescent nitrogen-, fluorine-, and sulfur-co-doped carbon dots (NFS-CDs) using flufenamic acid and L-cysteine as precursors. The synthesized NFS-CDs exhibited dual emission peaks at 490 and 580 nm with a quantum yield of 24.7 %. They exhibit excellent stability, excitation-dependent fluorescent, and particle sizes ranging from 2 to 8 nm. The fluorescent chemosensor probe, NFS-CDs, showed strong selectivity and sensitivity for Hg²⁺ over other metal ions investigated in aqueous solutions (pH ∼ 7.4). Strong fluorescent enhancement at 490 nm and considerable quenching at 580 nm was observed in the presence of Hg²⁺ ions. The stoichiometric ratio of the NFS-CDs/Hg²⁺ complex was optimized to 1:1 according to the Benesi-Hildebrand and Stern-Volmer plot methods. The NFS-CDs exhibited a linear dynamic detection range from 0 to 10 × 10^-6 M for Hg²⁺ ions with a lower detection limit of 18.0 and 67.5 × 10^-9 M, respectively, at 490 and 580 nm. Practical applications of NFS-CDs in detecting Hg²⁺ ions in natural water samples showed high recovery rates (98.9-104.6 %) and low relative standard deviation (RSD ≤ 2.47 %). The NFS-CDs/Hg²⁺ achieved 78.7 ± 2.6 % and 83.4 ± 2.3 % antibacterial activity against E. coli and S. aureus as NFS-CDs/Hg²⁺ could damage the bacterial walls when they entered the bacteria. Furthermore, the NFS-CDs were used to detect Hg²⁺ ions intracellularly in HCT116 cells with low toxicity using live cell imaging.

A highly sensitive detection system for α-amylase was developed via host-guest complexation between γ-cyclodextrin and dansyl-modified diphenylalanine (FF-Dns). The host-guest inclusion of FF-Dns into the cavity of γ-CD in a HEPES buffer solution (10 mM, pH 7.4) significantly enhanced the fluorescence intensity, and the emission wavelength gradually shifted from 558 to 535 nm. The hydrolysis of γ-CD by the addition of α-amylase released FF-Dns, leading to the recovery of the fluorescence emission characteristics. Therefore, the FF-Dns/γ-CD host-guest complexation system can serve as a platform for the sensitive detection of α-amylase with good selectivity against potential interference. The limit of detection (LOD) of the system was 0.004 U/mL, with a linear working range of 0-6 U/mL. The detection assay was successfully applied in 0.1 % serum, achieving an LOD of 0.017 U/mL and a linear working range of 0-10 U/mL.

In this paper, the molecular fluorescence probe H containing an imidazole structure was designed and synthesized by forming a ring between two amino groups and one aldehyde group. The synthesized probe H exhibits a Stokes shift of 144 nm with fluorescence emission at 555 nm and excitation at 411 nm. The fluorescence of probe H was quenched by the addition of Cu²⁺ and accompanied a red-shift of ultraviolet-visible (UV-Vis) absorption spectrum. Probe H reveals good selectivity and high sensitivity to Cu²⁺ in the fluorescence and UV-Vis absorption spectrum. And the limit of detection (LOD) for Cu²⁺ by fluorescence and UV-Vis spectrum methods were 0.14 nmol L^-1 and 1.34 μmol L^-1, respectively. The binding ratio of probe H and Cu²⁺ is 1:1 according to the Job's plot equation. High resolution mass spectrometry (HRMS) and density function theory (DFT) calculations proved that the solvent acetonitrile and anionic chloride ion participated in the formation of H-Cu²⁺ complex. Furthermore, the established fluorescence analytical method was successfully applied for the detection of Cu²⁺ and spiked recovery experiments in tap water and mineral water. In addition, the probe exhibited outstanding solid-state fluorescence because of its excellently planar structure, and displayed a secondary fingerprint structure in the application of fingerprint detection.

Water vapour plays a crucial role in atmospheric processes. Hence, monitoring the altitude-related variations in water vapour properties is important to decipher atmospheric processes. Direct tunable diode laser absorption spectroscopy (dTDLAS) measures the concentration and temperature of gas molecules by scanning the rotation-vibration absorption lines using a high-spectral-resolution laser. In this study, we devised an integrated measurement and data processing method (integrative measurement and processing method for hygrometry, IMPMH) to enhance the in-situ airborne measurement capability of dTDLAS. We measured a wide range (240-18,000 ppm) of water vapour concentrations, aiming for atmospheric measurements in a highly water-saturated regime, called the "optically thick condition". For recovering the full absorption spectra, the "integrative area" was defined and a difference factor D, which is the distance between two spectral regions with width corresponding to the half width of half maximum of the Voigt profile, was used to calculate the area. From the data, the low-bound concentration was measured to be 244 ppm. At D = 1.8, the transition concentration to the "optically thick condition" was measured to be 5,800 ppm. By increasing D from 1.8 to 2.8, the measurable upper-bound concentration increased to 17,993 ppm. IMPMH was applied to the measured data to estimate the final absorber density or water vapour concentration. The estimation was well-fitted with the measured detector signal with signal-to-noise ratio (SNR) of ∼ 300 of the residual spectrum, promising its applicability to in-situ airborne measurements. To validate IMPMH, the water vapour concentration range was divided into two regimes: (1) optically thick (5,800 < c < 18,000 ppm) and (2) optically thin (c < 5,800 ppm) conditions. Under the optically thick condition, IMPMH was validated by comparing the results between the short and long-path cells. In the optically thin condition, IMPMH was validated through comparison with the general dTDLAS method. Lastly, long-term stability of the dTDLAS system was validated by measuring 10 different concentrations (240-18,000 ppm) for 1000 s by characterising the precision and SNRs of the residual. The results demonstrate that IMPMH significantly enhances the in-situ airborne measurement capability of dTDLAS under both optically thick and thin conditions. Furthermore, requirements for the implementation of IMPMH in airborne measurement were investigated considering four aspects-sampling, low-pressure measurement, accuracy and precision, and multiplex detection. The results were examined with regard to atmospheric implications.

Melamine, often used as an adulterant in infants' formula due to its high protein content, can be harmful when ingested in large amounts, leading to the formation of cyanurate-melamine co-crystals in infants and potentially causing kidney damage. In this study, we introduce a fluorescent method for the selective and reliable detection of melamine in milk and infants' formula. The fluorescent probe comprises copper nanoclusters (Cu NCs) functionalized with thiosalicylic acid (TSA) and polyvinylpyrrolidone (PVP) as double-protecting ligands. Upon the addition of Hg²⁺, the fluorescence emission of TSA-PVP@Cu NCs is diminished due to static quenching. Subsequently, the fluorescence emission of the TSA-PVP@Cu NCs + Hg²⁺ probe is restored upon the introduction of melamine, facilitated by the coordination interaction between melamine and Hg²⁺ and the formation of a stable chelate between them. Under optimized conditions, the fluorescence emission was recorded initially for the TSA-PVP@Cu NCs + Hg²⁺ probe (F°) and after melamine addition (F). The (F/F°) ratio increased with rising melamine concentrations within the range of 0.025-65 µM. The detection limit, calculated using a signal-to-noise ratio of 3, was determined to be 8.0 nM. The TSA-PVP@Cu NCs + Hg²⁺ probe was successfully employed to detect melamine in milk and infants' formula, yielding acceptable recovery percentages and relative standard deviations. These results underscore the reliability and efficacy of the proposed probe for the fluorometric detection of melamine in real-world samples.