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

A zinc(II) coordination polymer, [Zn(H₂dhtp)(2,2'-bpy)(H₂O)]_n (1), has been utilized as a dual-mode luminescence-colorimetric sensor (H₂dhtp^2- = 2,5-dihydroxy terephthalate and 2,2'-bpy = 2,2'-bipyridine). The presence of hydroxyl groups in H₂dhtp^2- can promote excited-state intra- and intermolecular proton transfer (ESIPT) phenomena. Therefore, compound 1, which displays high stability in aqueous environments, exhibits a strong green-yellow photoluminescence. This luminescence signal can be considerably enhanced and blue-shifted upon the addition of Al³⁺ ions with a limit of detection (LOD) of 0.15 μM, and it demonstrates significant resistance to interference from several competing metal ions. To demonstrate a practical application, 1@paper strips were fabricated that can visually detect the Al³⁺ ion under a UV lamp. Moreover, 1 can detect either Fe²⁺ or Fe³⁺ ions in aqueous solutions by a visible color shift. Upon the incremental addition of Fe²⁺ or Fe³⁺ ions, the solution color changed from colorless to pink, exhibiting a pronounced absorption band at around 521 nm. The LODs were determined to be 1.55 and 0.34 μM for Fe²⁺ and Fe³⁺, respectively. Furthermore, compound 1 was used for the determination of Fe³⁺ ions in the real water samples, which can be evaluated on-site in real-time via a smartphone color-scanning application. The detection efficacy of 1 toward Al³⁺ and Fe²⁺/Fe³⁺ maintains significant luminescence stability and reusability.

Organic photovoltaics (OPVs) have improved greatly in recent years in pursuit for efficient and sustainable energy conversion methods. Specifically, utilizing quantum chemistry approaches such as density functional theory (DFT), the electronic structures, energy levels, and charge transport characteristics of donor-π-acceptor (D-π-A) systems based on non-fullerene donor and acceptor molecules have been examined and synthesized. Non-fullerene acceptors offer several advantages over traditional fullerene-based materials, such as enhanced light absorption, modifiable energy levels, and reduced recombination losses. Quantum mechanical simulations are helpful in the design and development of these materials because they can accurately predict the energy level alignment, molecule interactions, and charge transport properties needed for the high-efficiency of OPVs. The research begins through the selection of electron-donating and electron-accepting non-fullerene polymeric molecules using the unique properties of non-fullerene derivatives and non-fullerene acceptors. The theory uses the B3LYP-D3 method with a 6-31+G (d,p) basis set. PY-IT is used as the reference molecule, and eight molecules PY-IT01-PY-IT08, has been created by changing the end caps of the acceptor units. The created compound has superior photovoltaic characteristics. Focus has been specifically given to the frontier molecular orbitals (FMOs), natural bond order (NBO) analysis, reorganization energies (RE), and absorption spectra in order to assess the viability of charge separation and efficient light absorption. Finally, the molecular electrostatic potential (MEP) analysis, transition density matrix (TDM) analysis, and improved open circuit voltage (Voc) all have been computed. The results of the findings provide new insight to design organic solar cells (OSCs) with improved photovoltaic and solar energy conversion capabilities, which has great potential for the future development of more dependable and efficient OSCs.

Herein, nitrogen doped carbon quantum dots (N-CQDs) were synthesized using a hydrothermal strategy. The raw materials for the preparation of N-CQDs were sourced from pumpkin and melamine. The N-CQDs suggested fascinating water solubility, favorable UV and salt resistance stability. The fluorescence quantum yield of N-CQDs was carried out to be 16.7 %. The prepared N-CQDs suggested good optical features and favorable blue fluorescence under a UV lamp (365 nm). The as-prepared N-CQDs could be employed as rapid, sensitive and promising fluorescence nanoprobes to detect nifuratel because of static quenching and inter filter effect. For nifuratel detection, the linear range of 0.5-100 μM and detection limit of 0.074 μM were obtained. Furthermore, N-CQDs were subsequently applied to determine nifuratel in river water and Yili milk samples with acceptable experiment results. Significantly, N-CQDs suggested evident temperature-sensitive characteristics and were employed as fluorescent temperature sensing nanoprobes.

Alkenyl pheromones are a class of insect sex pheromones that are characterized by the presence of one or more double bonds, which can be either in the E(trans) or Z(cis) configuration. This structural variation is essential in mating, as it influences reproductive behavior and provides a potential method for insect control. As a base for rapid and in-situ screening of synthetic pheromones or pheromone-based products, this study explores the potential of Raman spectroscopy to differentiate between the two geometrical isomers, E(trans) and Z(cis), of the alkenyl pheromones. As a case study, four types of pheromones were analyzed: 5-decen-1-ol, 8-dodecyl acetate, 9-dodecyl acetate, and 10-dodecyl acetate; in the latter case, the E(trans) isomer was particularly investigated. In this regard, a detailed analysis of their experimental Raman spectra has been realized along with a DFT-based study of the investigated compounds. Moreover, to find the best machine learning (ML) model that can efficiently identify the E(trans) or Z(cis) isomers of alkenyl pheromones, several algorithms and two different designs of datasets were tested. The results indicate that the ML models could identify patterns and accurately predict the class even if the training dataset contains both experimental and theoretical data.

The relationship between human health and patulin (PAT) in the diet is a complex and intertwined one. The development of a sensing approach for the field detection of patulin is crucial, as the current approach lacks real-time detection capabilities and is costly in terms of material and technology. This paper presents a portable ratiometric fluorescence sensor that can be used to rapidly, accurately, and efficiently detect patulin in food items at the point of origin. The sensor employs a combination of sulfhydryl functionalized gold nanoclusters (MUA-AuNCs) and blue emission carbon dots (B-CDs), which have been engineered to serve as highly effective "on-off" nanoprobes. The modified sulfhydryl (SH) groups present on the gold clusters serve as specific recognition sites for patulin binding. The probes exhibit a discernible shift in hue, from orange-red to blue. The sensitivity detection limit (LOD) for patulin was found to be 0.019 μM, with a substantial linear correlation observed in the range of 0-2.2 μM. The objective of the combined chromatographic test strip and color recognition platform was to facilitate the sensitive, accurate, and real-time detection of patulin in foodstuffs, which is of paramount importance for the prevention of early disease. To facilitate rapid and straightforward preliminary testing of food security, it is anticipated that the integrated chromatographic strip ratiometric fluorescence sensing platform will be developed into portable home detection equipment.

Biodiesel is renewable energy source an alternative to conventional fossil fuels. The primary concern lies in detecting alcohol content in biodiesel, which can either be intentionally added by adulterants or remain in trace amounts from the refining process of biodiesel synthesis. In order to regulate the quality of biodiesel production, it is crucial to develop an analytical method for monitoring alcohol content in biodiesel. Present study identified Coumarin 153 (C-153) with outstanding solvatochromic characteristics in multiple biodiesel feedstocks (soybean, canola, sesame, and corn). Based on our spectroscopic investigations, this alcohol (methanol, ethanol, and propanol) sensing method has proven to be rapid, sensitive, ratiometric, and visually discernible, and the detection limit for ethanol in soybean biodiesel could reach 0.23 % v/v. The percentage of alcohol (0-100 % v/v) in the biodiesel determines significant changes in the lifetime values of the C-153 from 5.1 ns to 0.35 ns. Moreover, we depict explicit solvation models (ethanol) and implicit solvation models (biodiesel) from quantum chemical calculations to explain the experimental results. Based on our study, C-153 with alcohol sensing capabilities seems to have potential applications in biodiesel analysis. The present results will inspire future efforts to simplify and optimize the detection of alcohol in biodiesel by using optical methods.

The concentration of S^2- is a vital environmental indicator for evaluating the quality of source water, surface water, and wastewater, and it has a significant impact on biological systems, particularly human health. Therefore, it is crucial to detect S^2- selectively and sensitively. In this study, we developed a simple and rapid one-pot method to prepare a gold nanocluster (BSA-AuNCs) probe for fluorescence-enhanced detection of S^2- toxemia and analyzed the morphological characteristics of BSA-AuNCs and its complex with S^2- using various characterization techniques. The principle of the sensor is based on the interaction between S^2- and amino acids in the BSA molecular layer coated with gold clusters, regulating the rigid structure changes of gold clusters, and thus affecting the fluorescence properties of gold clusters. Through the specific interaction mechanism between proteins and gold-sulfur ions, this sensor exhibits excellent selectivity. It responds to S^2- in the range of 0 to 30 μM, with a detection limit of 0.395 μM, and shows no response to other heavy metal ions, anions, or amino acids. The sensor is environmentally friendly, simple to operate, has strong practicability, good precision, and recovery rate, and has potential application value in biological and environmental fields.

The presence of cells in urine and in particular White Blood Cells (WBCs) is often associated with Urinary Tract Infections (UTIs) and other diseases. Non-invasive screening of WBCs requires the development of cost-effective point of care diagnostic tools. Infrared (IR) spectroscopy has the potential to identify and quantify cells in urine. However, the quantification of cells by compact IR spectrophotometers can be hindered by the presence of highly concentrated interfering biomolecules. The use of separation procedures can assist in identifying and quantifying cells but reduces the point of care capabilities of the technology. In this study, we propose coupling cytocentrifugation with transflection IR spectroscopy for the isolation and quantification of cells in urine. Urine samples were spiked with monocytes and T-lymphocytes, cyto-centrifuged onto low-e slides and measured in transflection mode. An optional cell clean-up step, either performed before (by resuspending in PBS) or after the cytocentrifugation (by soaking the slide in water), was evaluated. In a first experiment using monocytes, IR band areas were linear (R² = 0.98) in the 8 × 10³-2 × 10⁵ cells mL^-1 range, thus demonstrating the detection of cells at pathological numbers (pyuria, i.e., >10⁴ WBCs mL^-1). Secondly, to mimic real samples with varying cell types, urine samples containing both monocytes and T-lymphocytes were analysed to determine their concentration simultaneously. Partial Least Squares (PLS) regression enabled the simultaneous quantification of two types of different cells, yielding prediction errors of 2 × 10⁴ cells mL^-1 for monocytes and 4 × 10⁴ cells mL^-1 for T-lymphocytes. The results suggest that the technique has the potential to be implemented as a fast, simple, versatile, and cost-effective method for quantifying and profiling cells in urine.

A self-driven and self-catalytic (SDSC) tripedal DNA nanomachine was developed for microRNA-21 (miR-21) detection. The microRNA could open one arm of tripedal DNA nanomachine to form DNAzyme with a nearby arm through the proximity effect. After DNAzyme's cleavage, the exposed DNA arm region competed with the third arm and produced a DNA segment (sequence Q). The released sequence Q initiated the next SDSC cycle of tripedal DNA nanomachine. In the special DNA nanomachines design, the components with close spatial localization were constructed on a single nanostructure, which significantly increased local reactant concentrations and reaction rates. A dynamic correlation was obtained from 10 pM to 50 nM between fluorescence signal and miR-21 concentration. The effective concentration of reactant greatly increased, compared with the free diffusible reactants. Consequently, the incubation time was significantly shorted to 35 min. This strategy showed a promising potential in miRNA detection and disease diagnosis.

The signal intensity ratio (SIR) is a crucial factor in advancing probe technology due to its direct impact on sensitivity and precision, particularly in applications such as medical imaging, environmental monitoring, and food safety testing. However, the development of high-SIR probes is challenged by complexities in fabrication, cost, and mechanical stability. In this study, we address these limitations by investigating the role of halogen atom substitutions in modulating the intermolecular binding energy and aggregation behavior of Ce-Salen Schiff base complexes. We synthesized a novel Schiff base pH probe, Ce-3,5-Cl-Salpn (3,5-Cl-Salpn = N, N'-bis (3,5-dichlorosalicylidene)ethylene-1,3-diaminopropane), and introduced its analogues Ce-5-Cl-Salpn (5-Cl-Salpn = N, N'-bis (5-chlorosalicylidene)ethylene-1,3-diaminopropane) and Ce-Salpn (Salpn = N, N'-bis (salicylidene)ethylene-1,3-diaminopropane) for comparative analysis. Through fluorescence measurements, single-crystal analysis, and theoretical calculations, we demonstrate that halogen substitution leads to significant modulation of fluorescence intensity and SIR in the pH range of 6.0 to 7.0. Notably, Ce-3,5-Cl-Salpn exhibited the highest SIR, with a 182.5-fold increase, compared to the non-halogenated variant's 9.2-fold rise. Frontier molecular orbital (FMO) analysis revealed a reduction in the HOMO-LUMO energy gap as halogen substitution increased, resulting in enhanced optical properties and more efficient electronic transitions. Additionally, binding energy calculations confirmed that halogen atoms strengthen intermolecular interactions, thereby improving molecular stability and aggregation-caused quenching effects.