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

A simple and highly sensitive isatin-based colorimetric sensor ISAT 3(a-d) was synthesized through a single-step reaction. The as-prepared receptor ISAT 3b with carbonate ions (CO₃^2- ions) shows a significant red shift in the UV-visible absorption spectra and a visible color change from pale yellow to pink. Also, the receptor ISAT 3b shows unique solvatochromic behavior with CO₃^2- ions in different aprotic solvents and solvent compositions. Moreover, the receptor's pink coloration (absorption maxima at 544 nm) with CO₃^2- ions could be reversible by adding HSO₄^- ions (attain initial pale-yellow color, absorption maxima at 425 nm), which can be repeatable. The observed color changes with spectral shift and reversibility of the receptor with CO₃^2- ions and HSO₄^- ions provide "ON-OFF" switching for applying molecular logic gates. Receptors exhibited properties, such as reversibility and repeatability, benefit the design of a molecular-scale sequential memory unit with a display of "Writing-Reading-Erasing-Reading". The real sample analysis was also carried out to prove the practical applicability of receptor (ISAT 3b) for detecting CO₃^2- ions.

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.

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.

The development and design of a novel, uniform and highly active local electromagnetic field enhanced structure is crucial for expanding Surface-enhanced Raman Scattering (SERS) applications. In this study, we developed Ag ring-coupled nanoarrays (Ag RCNAs) with controllable nanogaps using a substrate rotary evaporation coating technique with self-assembled polystyrene (PS) microspheres as templates. This straightforward and cost-effective method efficiently prepares plasma-coupled nanoarrays. Ag RCNAs demonstrated high sensitivity in detecting organic dyes, our prepared Ag RCNAs showed high sensitivity (with the limit of detection of 10^-8 M), high signal reproducibility (with the relative standard deviation of 6.73 %). Furthermore, Ag RCNAs showed remarkable sensitivity to a broad spectrum of dyes in river water, indicating the large-area uniform and highly active circular-ring-shaped nanogaps can realize highly sensitive detection of various pollutants. This approach offers advantages in electromagnetic field enhancement, tunable nanogaps, uniformity, reproducibility, and recyclability, making it promising for applications in environmental monitoring, bioassays, food safety, and medical diagnostics.

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.

Accurate postmortem interval estimation is vital in the investigation of homicides, suicides, and accidental deaths. It is key in narrowing suspect lists, improving crime-solving efficiency, and offering solace to bereaved families. The intra-puparial period, comprising about half of a fly's developmental cycle, presents challenges for morphological age estimation. External changes are limited to color shifts and the appearance of respiratory horns on the puparium only within several hours after pupariation, while detailed internal development analysis often requires invasive methods like removing the puparium, which can be damaging. Additionally, these techniques usually depend on a forensic entomologist's expertise, which lead to subjective biases. This study employed attenuated total reflection-fourier transform infrared spectroscopy, a rapid, non-destructive method for analyzing proteins, chitosan, and chitin in puparia. Data showed a consistent reduction in the concentration of the amide I band within the puparium during the intra-puparial development at five constant temperatures (19 °C, 22 °C, 25 °C, 28 °C and 31 °C). This trend in the spectral data effectively distinguishes pupae at various stages of intra-puparial development, facilitating precise age estimation, which is critical for the estimation of the minimum postmortem interval (PMI_min). Finally, this work combined the total reflection-fourier transform infrared spectroscopy with chemometric analysis and successfully developed a partial least squares discriminant analysis model and a random forest model, with accuracies of 88 % and 81 %, respectively. These models enable the non-invasive age estimation of P. regina in its intra-puparial period, a stage traditionally difficult to assess morphologically, thus laying the groundwork for PMI_min estimation using fly pupae.

A high-frequency, in situ fluorescence probe, called Fluocopée®, has been developed in order to better monitor variations in both the quality and quantity of dissolved organic matter within various aquatic environments (e.g. wastewater, receiving environments) thanks to a wide choice of 29 measured Excitation/Emission wavelength pairs. This advance pave the way to new measurement possibilities in comparison with existing probes, which are usually only able to measure 1-4 fluorophores. The qualification tests of the Fluocopée® probe indicate a high level of accuracy for the measurements of tyrosine, tryptophan and humic acids solutions. Good repeatability and reproducibility are also observed. For the first time, this tool has been deployed in an urban watershed (Bougival, Seine River, downstream of Paris) and in the settled effluent from a wastewater treatment plant (Seine aval, Achères, France). This new high-frequency in situ probe offers great application potential, including organic matter quality and quantity monitoring at drinking and wastewater treatment plants (treatment optimization) and in continental and marine waters (the fate of organic matter in biogeochemical cycles).

Miniaturized near-infrared (NIR) instruments are launched on the market to satisfy the need of both researchers and consumers for quick ways of analysing stuff, especially in the food field. Their portability and ease of operation are at the centre of the "do-it-yourself" idea behind providing virtually anyone with the ability of making analytical measurements on their own. In this study, we highlighted the convergence of technology and tradition in two seemingly disparate domains: spectroscopy and homebrewing. Homebrewing is in fact a leisure activity which conceptually shares the do-it-yourself approach: the consumer becomes the producer of his/her own beer. Hence, in our study, we investigated the analytical possibilities provided by a handheld NIR spectrometer to monitor the homemade fermentation process of a commercial malt extract, over the course of one week. The spectroscopic data, acquired using the SCiO sensor (Consumer Physics), were analysed via Principal Component Analysis (PCA) to investigate temporal trends and relationships with brewing parameters. Our findings reveal that discernible trends, reflective of brewing stage progression and temperature variations, can be captured and unveiled with simple data analysis approaches. At the same time, the detection of scattering effects that can be attributed to bubble formation on the spectrometer's acquisition window confirm the need for robust and reasoned experimental procedures, but also for proper data preprocessing methods. This rather simple and basic analytical approach could provide the homebrewer the possibility to qualitatively monitor the advancement of the brewing process.

Sulfur dioxide (SO₂), a toxic air pollutant, can have harmful effects on human health when inhaled or when it forms bisulfite in the body. In the present work, a ratiometric fluorescent probe, 2-(2'-hydroxyphenyl)benzothiazole-3-ethyl-1,1,2-trimethyl-1H-benzo[e]indolium (HBT-EMBI), was selected to study the mechanism of SO₂ derivatives detection. This study provides insights into the attributions of ratiometric fluorescence through hydrogen bond dynamics, electronic excitation properties, radiation rates, and excited state intramolecular proton transfer (ESIPT) processes using the density functional theory (DFT) and the time-dependent density functional theory (TDDFT) level. The results confirm that the large Stokes shifts and broad emission spectra of the HBT-EMBI probe are associated with its intramolecular charge transfer (ICT) characteristics and hydrogen bonding-driven ESIPT processes, respectively. After the addition reaction between the probe and HSO₃^-/SO₃^2-, the conformational populations of HBT-EMBI-HSO₃^- transfer abnormally from enol configurations to more stable keto configurations, which leads to a distinguished change in the visible color and the ratiometric fluorescence signal, and is not due to the blockage of the ICT process of HBT-EMBI-HSO₃^-, as previously reported. This work provides a new perspective on the mechanism of detection of SO₂ derivatives by ESIPT fluorescent probes.

This research addresses the challenge of analyzing pregabalin, a primary amine in a zwitterionic structure, which is difficult to evaluate due to its lack of chromatophore. The study introduces a derivatization assessment using Hantzsch's multicomponent organic reaction to enhance the detectability of pregabalin by forming a highly fluorescent dihydropyridine derivative. This process involves the condensation of pregabalin with acetylacetone and formaldehyde, yielding a yellowish-green compound measurable both colorimetrically at 338 nm and fluorimetrically at an emission wavelength of 486 nm (λ_excitation = 408 nm). The reaction conditions were thoroughly optimized to obtain the highest possible sensitivity, reduce reagent and time consumption, and use safe solvents. The developed method displayed high sensitivity and linearity in the concentration ranges of 4.0 - 20.0 µg/mL in colorimetric assay and reached a nano-scale analysis level of 40 - 2000 ng/mL with a detection limit down to 10 ng/mL when adopting the fluorimetric measurement. Both assessments were rigorously evaluated for their performance, adhering to the International Conference on Harmonization (ICH) standards. The accuracy of these methods was confirmed through the recovery rates of real samples, showing 98.9 ± 0.2 % for colorimetric and 98.2 ± 0.7 % for fluorimetric assessment. The excellent sensitivity of the suggested spectrofluorometric approach led to its use in the measurement of PRG in spiked human urine samples, resulting in particularly good recoveries ranging from 95.3 to 102.8 %. Meanwhile, the Need, Quality, Sustainability (NQS) index looks into how necessary the method is, execution quality (evaluated using the RGB 12 algorithm), and how it fits with the Sustainable Development Goals (SDGs), underlining the benefits of employing natural reagents. The developed approach showed superiority in sensitivity and sustainability compared to previous analytical approaches for pregabalin.