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

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.

In order to solve the problem of poor sensitivity and selectivity of conventional SERS substrates, we synthesized Mo_1-xW_xS₂@Ag₂S nanosheets in this paper by a two-step hydrothermal method. The structure and morphology of the synthesized Mo_1-xW_xS₂@Ag₂S nanosheets were characterized by XRD and SEM,respectively. The results show that the Mo_1-xW_xS₂@Ag₂S nanosheet has an irregular layered structure. Further, the SERS properties of Mo_1-xW_xS₂@Ag₂S nanosheets were tested by using rhodamine 6G (R6G), crystalline violet (CV), and 4-mercaptobenzoic acid (4-MBA) as probe molecules, respectively. The test results demonstrated that the nanosheets were specific to R6G and CV probe molecules, and the mechanism of selectivity was due to CT enhancement. In addition, Mo_1-xW_xS₂@Ag₂S exhibits ultrahigh sensitivity in R6G and CV, with the corresponding detection limit of both reached 10^-8 M. And linear fitting of the peak intensities was carried out, with the R² coefficient of 0.981 and 0.951, respectively. Finally, the relative standard deviations (RSDs) of this Mo1-xWxS2@Ag2S nanosheets was obtained to be 8.56 % by test 1 × 10^-4 M R6G at the characteristic peak 613 cm^-1, which represents excellent detection repeatability. The Mo_1-xW_xS₂@Ag₂S nanosheets are rich in edge-active sites favorable for charge transfer, which can enhance the SERS signals of the target molecules better. Besides, the Raman detection of the surface of Mo_1-xW_xS₂@Ag₂S nanosheets using nitrofurantoin (NFT) also reached a detection limit of 10^-8 M. Mo_1-xW_xS₂@Ag₂S nanosheets substrates can find applications in medicine and provide new strategies for improving the SERS performance.

Simple and eco-friendly biodegradable hydrotropes-assisted spectrophotometric experiments have been designed and validated to quantify ranolazine hydrochloride (RAN.HCl) in extended-release tablets. The citric acid and sodium citrate are employed as hydrotropes, serving as promising alternatives to polar organic solvents. The development of rapid and specific spectrophotometric experiments aimed at enhancing the spectral absorption of RAN.HCl. The spectrophotometric experiments are D⁰ and D^{0 AUC}, in which the highest peak absorbance was observed at 270.50 nm, with an AUC ranging from 265.00 to 275.50 nm. Moreover, spectral analysis of D¹ and D² were conducted with peak amplitudes recorded at 280.00 nm and 274.40 nm, respectively. The AUC in the wavelength ranges 275.00-287.00 nm for D¹, and 265.00-279.50 nm for D² were implemented to quantify RAN.HCl confirms no interference from the common additives incorporated into the marketed preparation. The optimized experiments disclosed a linear relationship in the 0.02-0.16 mg/mL concentration range. The accuracy was performed at 50-150 %, revealing an overall average recovery of 100.02 %. The lowest limits of RAN.HCl that could be accurately detected and quantified were 0.0016 and 0.0049, 0.0018 and 0.0055, 0.0058 and 0.0176, 0.0024 and 0.0075, 0.0074 and 0.0224, 0.0021 and 0.0064 mg/mL, respectively, across these investigations. Statistical analysis revealed no significant differences between the outcomes of the present investigation and those documented in literature reports, based on the t- and F-values at p = 0.05, which were below the theoretical values of 2.2622, 2.3646, 6.26, and 19.20, respectively.

The present work reports a sensitive, affordable, and ecologically friendly spectrofluorimetric method for the assessment of two antihypertensive medications, namely minoxidil and timolol. Blue-emitting sulfur and nitrogen co-doped carbon quantum dots (S,N-CQDs) were generated by exposing soluble starch and thiourea to a 15-minute microwave treatment. The so- prepared nanodots displayed fluorescence at 276/430 nm with a quantum yield of 22 %. Inspection of the so-prepared nano-sensor verified their doping with nitrogen and sulfur, and their size was in the range of 4.5-9.03 nm. The proposed method was found to be rectilinear in the range of 0.20-5.0 and 2.0-30.0 µg/mL, with LOQs of 0.16 and 0.82 µg/mL for minoxidil and timolol, respectively. The developed method was employed to assess the concentrations of minoxidil and timolol in their pharmaceutical formulations, with %recoveries varying between 99.00 % and 101.94 %, and low RSD values (less than 2 %). The high sensitivity of the developed method allowed its use for timolol measurement in artificial aqueous humor, with % recoveries between 97.60 %.and 101.57 %. The study further examined how each analyte interacted with the prepared dots, leading to a quenching of their fluorescence. Additionally, an interference study was utilized to evaluate the specificity of the proposed approach through determining analyte levels in the existence of common additives, co-formulated drugs, and co-administered drugs. The analytical eco-scale, GAPI and AGREE assessment techniques were utilized to confirm the suggested method greenness.

A novel colorimetric and fluorescent thiophenol probe based on dicyanoisophorone has been successfully achieved, which has low-cost, easy operation, high selectivity, sensitivity and stability. The chemosensor shows a large Stokes shift and approximately 170 nm when excited at 510 nm. ISO-DiNO₂ could be utilized as "Turn-on" and a naked-eyes chemosensor to detect PhSH, which is accompanied by a distinct color shift from red to dark purple with strong red fluorescence at 365 nm UV-light. Its limit of detection was determined to be 1.15 μM. More importantly, ISO-DiNO₂ can react instantaneously (<10 s) with PhS^-. In addition, ISO-DiNO₂ has been utilized in test paper strips, water sample together with imaging of PhS^- in living Raw264.7 cells, demonstrating that ISO-DiNO₂ has excellent and promising applications.

Herein, we report pyrene-tagged amide and urea-based sugar derivatives 1 and 2 in a simple synthetic pathway to recognize I^- and Hg²⁺ ions. Both molecules showed absorbance and fluorescence selectivity towards iodide ions in THF/H₂O (7/3, v/v) medium. The selectivity and sensitivity of 2 for iodide ions are superior to 1 due to more H-bond donors in 2. Interestingly, fluorometric receptor 2 exhibited aggregation-induced emission (AIE) at higher pH with a remarkable fluorometric color change. The AIE phenomenon might be explained by the self-association of 2 after forming imine functionality in the alkali medium. The Stern-Volmer plot showed the fluorescence quenching constant of each receptor with an iodide ion and indicated the quenching pathway. The LODs of 1 and 2 for iodide ions were evaluated as 0.84 and 0.17 µM, respectively. The 1:1 binding stoichiometry of 1 or 2 with iodide was found from the Job plot and verified by measuring the complex mass. Further, the complexes of each receptor with I^- ions can detect Hg²⁺ ions selectively by fluorescence turn-on method with low sensitivities (LODs: 0.008 µM for 1 and 0.01 µM for 2). DFT results were used to understand the binding mode of receptors 1 and 2 with iodide ions and the quenching process in the aqueous THF medium. The real application of the receptors was established for the recovery of iodide and Hg²⁺ ions from natural water samples.