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Organic chromophores such as the thionated derivatives of perylene diimides (PDIs) show prolonged triplet-excited state lifetimes in contrast to their pristine parent PDI molecule, which shows near unity fluorescence quantum yield. The excited state dynamics in the trans-dithionated PDI (S2-PDI) are studied here. Unlike PDI, the photo absorbing ππ* state of S2-PDI is in close proximity to quasi-degenerate nπ* states. The latter exhibits an interesting vibronic problem leading to the breaking of orbital symmetry mediated through non-totally symmetric vibrations. The time-dependent quantum dynamics are studied with a diabatic model Hamiltonian involving three singlet and three triplet states coupled via 22 vibrational modes. A combined effect of multiple internal-conversion and inter-system crossing (ISC) pathways leads to population transfer from the 1ππ* state to the 3ππ* state via the nπ* states, with an overall ISC rate of 0.70 ps that compares well with the experimental value. The calculated absorption spectra for PDI and S2-PDI reproduce the essential vibronic features in the observed experimental spectra. The dominant vibronic progressions are found to have significant contributions from the vinyl stretching modes of the PDI core. [ABSTRACT FROM AUTHOR]

Cationic acridine dyes acted as a stabilizer for glucose oxidase adsorbed on a pencil graphite electrode and enhanced mediated bioelectrocatalysis for glucose oxidation. The order of the magnitude of the bioelectrocatalytic current was consistent with the binding constants estimated by fluorescence quenching and the binding energies estimated by docking simulation. [ABSTRACT FROM AUTHOR]

In the realm of allene hydrofunctionalizations, controlling the selectivity of radical additions to allenes has constituted a formidable challenge for many years. Here, we present a sustainable strategy for visible-light-induced hydrophosphorylation of allenes with H-phosphine oxides in green solvents. Under the mild reaction conditions, a diverse range of alkenylphosphoryl compounds are synthesized through a radical pathway in a highly stereoselective and regioselective manner. The regioselectivity can be precisely modulated by altering the substituent patterns on the allene substrates. Mechanistic investigations, including control experiments and fluorescence quenching studies, have elucidated the phosphinoyl radical pathway of the reactions. Computational studies indicate that the catalytic cycle involves sequential reactions, including radical addition, single electron transfer, and proton transfer, with the latter step being identified as the determinant of regioselectivity. [ABSTRACT FROM AUTHOR]

The molecular interactivities between proteins and polysaccharides exhibit a profound role in characteristics of binary hydrogels. The binary gels were characterized from the major aspects; molecular behavior, microstructure, texture, rheology, water-holding capacity (WHC), and swelling ratio (SR). Despite previous articles claiming the electrostatic interactions to be the main driving forces of gelation, it was shown that gelation of animal-derived proteins and polysaccharides are totally in line with hydrogen and hydrophobic forces. Polysaccharides unfold proteins, evidenced by increased surface hydrophobicity and fluorescence quenching. Polysaccharides modify both secondary and tertiary structures of proteins by facilitating the transition of α-helix to β-sheet along with all-gauche conformation to trans-gauche-gauche. The π-π stacking causes enhanced adhesiveness, elasticity, gel strength, springiness, resistance to fracture, WHC, and SR. Increased specific surface area and surface active energy enhance the gelation properties. Both excessive total polymer concentrations and hydrophobic interactions weaken the structure. Polysaccharide addition enhanced the gel tendency toward water, so WHC and SR increased. However, excess protein reduction abruptly reduced them. Therefore, a threshold was known for protein/polysaccharide mass ratio. In common, polysaccharide made the structure harder than single protein gel. [ABSTRACT FROM AUTHOR]

The widespread use of antibiotics in water has resulted in significant environmental contamination, posing potential health risks. This necessitates the development of efficient methods for their removal from wastewater. This review explores the potential of UiO (Universitetet i Oslo) metal–organic frameworks (MOFs) for the adsorption of dyes and pharmaceuticals from water. UiO MOFs possess exceptional characteristics, including ultra-high porosity and remarkable stability, making them ideal candidates for pollutant adsorption compared to traditional adsorbents. Studies have demonstrated the exceptional performance of UiO MOFs in removing antibiotics from water at various concentrations. This high adsorption efficiency is attributed to their extensive Brunauer–Emmett–Teller (BET) surface area and pore volume, offering numerous binding sites for pollutants. The adsorption affinity between UiO MOFs and antibiotics is governed by various interactions, such as electrostatic interactions, hydrogen bonding, and π–π stacking. These interactions are influenced by the surface charge of the target pollutant and the zeta potential of the MOF surface. Furthermore, the detection mechanisms for antibiotics including, fluorescence quenching, photocatalytic degradation, adsorption, sensing, and other methods, are discussed in this review. Overall, this review emphasizes the promising potential of UiO MOFs as efficient adsorbents for removing antibiotics from water, offering a viable solution for environmental cleanup. [ABSTRACT FROM AUTHOR]

Given the increasing demand for white light emitting diode (WLED) lighting devices marked by high color rendering indices (CRI) and exceptional thermal stability, there is a burgeoning interest in developing emitters with enhanced performance. Rare earth (RE) ion-activated glass ceramics (GCs) have garnered significant attention due to their outstanding physicochemical and thermal stability, alongside their high luminescence efficiency. In this study, the GCs doped with Tb3+ ions in the Na 2 O-CaO-SiO 2 system matrix were synthesized, incorporating Na 2 Ca 2 Si 3 O 9 nanocrystals averaging less than 100 nm in size. Notably, these GC materials demonstrated superior luminescence efficiency in the green light emission under the irradiation of 376 nm light compared to the parent glass. A comprehensive analysis of fluorescence spectra revealed an impressive internal quantum efficiency of 87.34 % for this Tb3+-doped GC. Furthermore, the GC retained 90 % and 84 % of the initial luminescence intensity at 150 °C and 200 °C in comparison to the luminescence level at room temperature, showcasing exceptional resistance to fluorescence thermal quenching. Verification experiments utilized UV LED chip, (Sr, Ca)AlSiN 3 : Eu2+ red phosphor, BaMgAl 10 O 17 : Eu2+ blue phosphor, and Tb3+-doped GC to encapsulate the WLED device, achieving a remarkable CRI of 92, CIE chromaticity coordinates (0.3547, 0.3361), and a correlated color temperature (CCT) of 4550K. In conclusion, the experimental outcomes unequivocally underscore the significant application potential of these Tb3+-doped GCs in the territory of warm WLED lighting. [ABSTRACT FROM AUTHOR]

Emission and excitation spectra of fluorescence (FL) were studied for aqueous solutions of ATP with AgNO3 salt at different concentrations of silver nitride and temperatures. It is shown that with increasing Ag+ content and temperature, a complex nature of FL quenching occurs due to the formation of ATP - Ag+ complexes. This quenching occurs when the position of the emission bands and FL excitation of the ATP fluorophore is preserved, and the quenching corresponds to the Stern-Volmer linear dependence. At the same time, the values of KSV and kq and their dependence on the temperature indicate a static quenching mechanism. The binding parameter n indicates that the metal–ligand complexes have a stoichiometric ratio of 1:1, and KA decreases with increasing temperature. In the heteroassociates, energy is transferred by the FRET mechanism, and binding of components is mainly realized due to electrostatic and van der Waals interaction. [ABSTRACT FROM AUTHOR]

Electron donor–acceptor (D–A) molecules are emerging tools for designing sensitive luminogens, attracting significant research attention. However, due to poor quantum yields under certain conditions, current D–A fluorophores often suffer from fluorescence quenching in practical applications. Developing new D–A dyes and functional composites is crucial for expanding their applications. Here, a novel donor–acceptor type flavonoid dye molecule, namely “AFL”, exhibiting both polarity‐dependent fluorescence emission wavelength shift and viscosity‐dependent intensity change, for polarity measurement and temperature sensing is designed and synthesized. Because the intramolecular charge transfer (ICT) can be enhanced by a decrease of excited state energy caused in high‐polarity organic solvents, AFL undergoes fluorescence emission wavelength shift that shows fluorescence color response to solvents of different polarities and hence differentiates between them. Moreover, the actual temperature can be monitored by the as‐designed AFL@tetradecanoic acid (AFL@TA) sensor. By combining with TA, viscosity sensitively changes upon the temperature change of insoluble composites, thus realizing the fluorescence intensity response to temperature. Remarkable recyclable performance and satisfactory mechanical properties are integrated. This study provides a promising approach to developing a new D–A fluorescent probe and furnishes perspectives on the potential of such D–A type flavonoid material in stimuli‐responsive systems with a focus on visualization sensing technology. [ABSTRACT FROM AUTHOR]

In order to obtain food packaging film with better performance, whey protein concentrate (WPC) and egg white protein (EWP) were used as film‐forming substrates, and its film properties were modified by transglutaminase (TG). Then the effect of TG on the mechanical, physical, barrier, and microstructural properties of the WPC/EWP composite biodegradable film was investigated, and its preliminary application potential was explored. Compared to WPC and EWP films, WPC/EWP composite film had higher transmittance, tensile strength (TS), and thermal stability. Fluorescence results showed that the film experienced fluorescence quenching after TG treatment. Fourier transform infrared and x‐ray diffraction results showed that WPC and EWP had good compatibility in the biodegradable film, the hydrogen bond interaction of film was increased due to TG, resulting in an increase in TS. Meanwhile, the water vapor permeability and contact angle of WPC/EWP film treated with TG at 5 U/g protein increased by 28% and 76.1%, respectively. Besides, the WPC/EWP biodegradable film modified by TG (TG‐W/E) was applied as a coating film on cherry tomatoes, effectively reducing the weight loss rate during storage from 14.2% to 10.8%. Furthermore, indexes, such as solid content, spoilage rate, hardness, pH, and lycopene, showed that the film had a good preservation effect on cherry tomatoes. To conclude, the appropriate addition of TG has a positive effect on the film properties of the WPC/EWP biodegradable film, which is beneficial to the development and utilization of protein‐based film. WPC/EWP biodegradable film modified by TG has a great application prospect in extending the shelf life of fruit and vegetable. [ABSTRACT FROM AUTHOR]

Although many dyes have been introduced into cellulose, whether bound to its backbone or within a cellulose matrix, few studies have determined whether the backbone statically or dynamically quenches the photoluminescence of the dye. To advance cellulosic fluorescent films, the influence of the cellulose backbone on photoluminescence must be understood. We determined the fluorescence properties of fluorescein isothiocyanate (FITC) and fluorescein-labeled cellulose (FLC) in water and alcohol, including their quantum yields , lifetimes , and rates of radiative and nonradiative decay. Dissolved FLC had a ~ 30× lower than FITC, suggesting that incorporating FITC into the cellulose backbone remarkably reduces the fluorescence efficiency. The FLC solutions had a six-fold lower than their FITC counterparts but a 10–20 times higher . Presumably, this was because the cellulose backbone interacted weakly with the fluorescein moieties, suggesting a quenching mechanism that can be termed quasi-static, corresponding to static quenching between the fluorescein moieties and cellulose backbone, in addition to the fluorescence quenching caused by the intramolecular nonradiative processes of fluorescein, as observed in conventional molecules. Using the Strickler‒Berg formula, we deduced the analytical radiative decay rate constants and eventually estimated the number of very short-lived fluorescein moieties per single fluorescent fluorescein moiety, corresponding well with static quenching. [ABSTRACT FROM AUTHOR]

The widespread use of herbicides like dinitro-o-cresol (DNOC) and veterinary drugs such as furaltadone (FLT) has surged to meet agricultural and animal husbandry demands, raising significant health and environmental concerns due to their extensive use and unregulated disposal. To address this issue, herein, we developed an imidazole-functionalized metal–organic framework (MOF)-based fluorometric dual sensor for rapid and selective detection of these analytes in aqueous medium. The present MOF-based probe demonstrated 82% fluorescence quenching upon DNOC introduction, whereas 89% quenching occurred in the presence of FLT. The probe exhibited notably high sensitivity, with the lowest ever reported limit of detection (LOD) of 0.5 nM for DNOC and 1.1 nM for FLT. The highest reported Stern–Volmer quenching constant (KSV) value of 5 × 107 M−1 and 2 × 107 M−1 for DNOC and FLT, respectively, further indicates the extraordinary sensitivity of the sensor towards these targeted analytes. The MOF showed a rapid response time of 5 s for both DNOC and FLT. The sensor also demonstrated outstanding selectivity even in the presence of interfering substances, proving effective in various complex environments such as serum, urine, wastewater, and different pH media. We thoroughly investigated the sensor's working mechanisms using different advanced analytical techniques to understand its high selectivity towards the targeted analytes. These findings underscore the sensor's practical and potential real-world applications, offering a valuable tool for environmental pollution monitoring and public health protection. [ABSTRACT FROM AUTHOR]

A post-synthetic modification was employed to incorporate lanthanide Eu3+ ions into carbazole-functionalized UiO-67 metal–organic frameworks, successfully fabricating an efficient dual-emission fluorescence probe. The Eu3+-doped composite manifests superior luminescent properties and remarkable fluorescence stability, attributable to the sensitization and reinforcement afforded by the parent framework. Notably, the ligand's capability to capture external light and sensitize Eu3+ emissions led to observing characteristic peaks at 435 nm for the intrinsic ligand and 591, 614, 651, and 701 nm for Eu3+. The introduction of dipicolinic acid (DPA) serves a dual role: it acts as an antenna to absorb photons and replaces the coordinated water molecules of Eu3+, thereby preventing fluorescence quenching by water's O–H vibrations. Additionally, establishing hydrogen bonding between DPA and the carbazole dicarboxylic acid (CDC) initiates an intermolecular charge transfer (ICT) process, enhancing the ligand's fluorescence. Besides, the addition of DPA concurrently enhances the fluorescence emissions of both the ligand and Eu3+, displaying an unusual dual-enhanced "turn-on" fluorescence mode with an impressively low detection limit of 0.538 μM, accompanied by discernible color changes visible to the naked eye. Utilizing Eu@UiO-67-CDC as a test paper facilitates rapid on-site detection of DPA, eliminating the need for complex instrumentation. Moreover, the Eu@UiO-67-CDC probe can quantify DPA in environmental matrices such as river and lake water, with better recovery rates, indicating its significant potential for practical applications. [ABSTRACT FROM AUTHOR]

A novel category of asymmetric boron chromophores with the attachment of two BF2 moieties denoted as BOPAM has been successfully synthesized via a one‐pot three‐step reaction starting from N‐phenylbenzothioamide. This synthetic route results in the production of [a] and [b]benzo‐fused BOPAMs along with post‐functionalization of the [a]benzo‐fused BOPAMs. The photophysical properties of these compounds have been systematically investigated through steady‐state absorption and fluorescence emission measurements in solvents at both ambient and cryogenic temperatures, as well as in the solid state. Computational methods have been employed to elucidate the emissive characteristics of the benzo‐fused BOPAMs, revealing distinctive photophysical attributes, including solvent‐dependent fluorescence intensity. Remarkably, certain BOPAM derivatives exhibit noteworthy photophysical phenomena, such as the induction of off‐on fluorescence emission under specific solvent conditions and the manifestation of intermolecular charge transfer states in solid‐state matrices. Through post‐functionalization strategies involving the introduction of electron‐donating groups onto the [a]benzo‐fused BOPAM scaffold, an intramolecular charge transfer (ICT) pathway is activated, leading to substantial fluorescence quenching via non‐radiative decay processes. Notably, one [a]benzo‐fused BOPAM variant exhibits a pronounced fluorescence enhancement upon exposure to acidic conditions, thereby underscoring its potential utility in pH‐sensing applications. [ABSTRACT FROM AUTHOR]

ABSTRACT Novel bioactive ternary nickel (II) complexes, [Ni(5BrSal‐Phe)(phen)] (1) and [Ni(5BrSal‐Tyr)(phen)] (2) (5BrSal‐Tyr: Schiff base derived from 5‐bromosalicylaldehyde and L‐tyrosine, 5BrSal‐Phe: Schiff base derived from 5‐bromosalicylaldehyde and L‐phenylalanine, phen: 1,10‐phenanthroline), have been synthesized and characterized by electronic absorption spectroscopy, CHN, FTIR, ESI‐MS and X‐ray crystallography techniques. Interaction of the complexes with biomolecules (calf thymus DNA (CT‐DNA) and bovine serum albumin (BSA)) has been investigated by electronic absorption and fluorescence spectroscopy. The results show that the complexes can bind to CT‐DNA via a minor groove binding mode. Moreover, the fluorescence quenching mechanism between the complexes and BSA is a static quenching process. The antiproliferative activities of the complexes against breast cancer cells (MCF‐7 and MDA‐MB‐231) and healthy breast epithelial cells (MCF‐10A) were investigated. The complex 2 was found to have promising antiproliferative activity in selected cell line, with lower IC50 values than cisplatin. Molecular docking studies suggest that the complexes may serve as potential chemotherapeutic agents. These complexes have been observed to interact with various targets within cells, including the epidermal growth factor receptor (EGFR), bovine serum albumin (BSA), and B‐DNA. Analyses indicate that these interactions are supported not only by conventional hydrogen bonds but also van der Waals forces and π‐π interactions. Additionally, determining binding constants and regions enhances our understanding of how the complexes interact with target molecules. The results emphasize the importance of the complexes in cancer therapy by highlighting the necessity of understanding their molecular‐level interactions with targets. [ABSTRACT FROM AUTHOR]

A highly selective fluorescent "turn on" probe for Al3+ based on the conjugate of aminourea and pyrazolone was devised and synthesized. The fluorescence intensity of the probe solution was significantly enhanced by the addition of Al3+ to the probe solution. Other cations such as Cu2+, Ni2+, Fe3+, Co2+, Ag+, Mn2+, Sn2+, Sn4+, Mg2+, Li+, Zn2+, Zr4+, Ce3+, Ca2+, and Na+ did not interfere the detection of Al3+. The 1 : 1 complexation between Al3+ and the probe was confirmed by Job's plot curve. In addition, the solution of the complex formed by Al3+ and the probe can be used for the specific detection of Hg2+, appearing as fluorescence quenching. [ABSTRACT FROM AUTHOR]

Diosmetin (Dio) has attracted much attention because of its good pharmacological effects, thus it is necessary to determine its content in scientific research and production. In the study, stable orange‐red copper nanoclusters with 4‐hydroxy‐2‐mercapto‐6‐propylpyrimidine (PTU) as reducing agent and ligand (PTU‐CuNCs) was prepared by a simple approach with superior quantum yield (18.03 %), and the PTU‐CuNCs with red fluorescence could improve the anti‐interference ability of detection. Meanwhile, the synthesis conditions of PTU‐CuNCs were optimized and analyzed in detail. Through a series of experiments, it was found that inner filter effect (IFE) and dynamic quenching might become the main reasons for the fluorescence quenching of PTU‐CuNCs by Dio. Based on the mechanism, a fluorescence probe for the determination of Dio was established. In the range of 0.33–31.67 μmol L−1, the fluorescence quenching efficiency of PTU‐CuNCs was linearly related to the contents of Dio, and corresponding limit of determination (LOD) was estimated to be 101.3 nmol L−1, and limit of quantitation (LOQ) was calculated to be 337.4 nmol L−1. Furthermore, the method could be used effectively for the assay of Dio in practical samples. [ABSTRACT FROM AUTHOR]

ABSTRACT Antibiotic pollution in hydrophytic ecosystems has aroused widespread notice due to its adverse impact on both the ecological environment and human physical well‐being. Thus, the development of effective antibiotic detection materials is not only urgently needed but is also challenging. Herein, the luminescent metal–organic framework [Mn3/2(HBCTC)·5H2O] (1) was successfully synthesized based on [9,9′‐bicarbazole]‐3,3′,6,6′‐tetracarboxylic acid (H4BCTC) under solvothermal conditions. Compound 1 can be employed as a fluorescent probe to detect antibiotic difloxacin hydrochloride (DIF) in water, demonstrating a remarkable linear relationship between fluorescence intensity ratio I0/I and the concentration of DIF (0–40 μM), with Ksv of 79,405 M−1 and LOD of 114 nM. More importantly, 1 represents the first fluorescent sensing material based on MOF for the detection of DIF, exhibiting exceptional selectivity, sensitivity, and anti‐interference capability. Furthermore, the mechanism of fluorescence quenching was studied comprehensively. [ABSTRACT FROM AUTHOR]

A multifunctional fluorescent probe P based on a naphthalimide derivative for the detection of Ag+ and Hg2+ through a dual-signal was designed and characterized. P exhibited a large Stokes shift (107 nm), high selectivity, good sensitivity, and fast response time. By adjusting the testing medium and the order of reagent addition, multifunctional detection with P was achieved. The addition of Ag+ or Hg2+ to P solution in either ethanol or an ethanol–water mixture resulted in a significant quenching of fluorescence emission at 537 nm and caused a decrease in the absorbance at 440 nm accompanied by the appearance of a new absorption peak at around 340 nm, and there was an obvious color change from yellow to colorless. In contrast, the addition of other common metal ions and anions did not produce substantial spectral or color changes. The detection limit of probe P for Ag+ and Hg2+ was calculated to be 0.33 μM. The sensing mechanism was proposed and validated through MS and 1H NMR spectrometry methods. Additionally, P demonstrated the capability to recognize Ag+ and Hg2+ in living cells with satisfactory results. [ABSTRACT FROM AUTHOR]

A quinoxaline‐based ligand, 6,7‐dimethyl‐2,3‐di(2‐pyridyl)quinoxaline (Me2dpq), and its unique binuclear Co(II)‐Me2dpq complex were prepared and analyzed using single crystal X‐ray diffraction and several spectroscopy techniques. Hirshfeld surface analyses were also used to clarify the Me2dpq ligand and the Co(II)‐Me2dpq crystal packing. The Co(II)‐Me2dpq complex crystallized in triclinic P‐1 space group and exhibited a distorted trigonal bipyramidal geometry around the cobalt(II) ion. Each Co(II) ion coordinated to a Me2dpq ligand through two N donor centers from pyridyl and quinoxaline rings along with a terminal Cl and two bridged Cl atoms. The binding properties of the ligand and its complex with CT‐DNA were studied by several techniques, namely UV–Vis spectroscopy, fluorescence quenching, viscosity measurements, thermal denaturation, and gel electrophoresis. The CT‐DNA binding interaction tests demonstrated that both the Co(II)‐Me2dpq complex and its parent ligand bind to DNA in an intercalative way. The antioxidant studies of the novel Co(II)‐Me2dpq complex illustrated significant activity against DPPH• and OH•· radicals. The in vitro cytotoxic effect of Me2dpq ligand and its Co(II)‐complex on MCF‐7 and Hep‐G2 tumor cell lines was evaluated by using the MTT assay. The studies showed that the Co(II)‐Me2dpq complex had superior activity toward the tested cell lines. Molecular docking studies of synthesized compounds were employed to figure out the way they would associate with a biologically macromolecular target B‐DNA (PDB: 1BNA). Thus, this study is anticipated to provide novel opportunities for the successful utilization of the synthesized compounds in many medical domains. [ABSTRACT FROM AUTHOR]

The present research utilizes the simple "plug-and-play" strategy to effectively impart layered rare-earth hydroxides with remarkable sensitivity, selectivity, and rapid fluorescence sensing detection ability towards nitroaromatic compounds, employing the excited-state proton transfer fluorescence quenching mechanism. This opens new possibilities for the efficient and accurate detection of toxic and hazardous nitroaromatic compounds and effectively protecting environmental health and public safety. [Display omitted] Convenient, rapid, and accurate detection of nitroaromatic organic toxins and harmful substances is of great significance in research. In the present study, two-dimensional layered rare-earth hydroxides (LYH) were used as ion-exchange matrix materials, and the anionic fluorescent dye molecules (HPTS) were successfully introduced into the LYH structures in situ via a simple and effective "plug-and-play" strategy, which gave the compounds ultra-sensitive fluorescence sensing detection of nitrobenzene, p-nitrotoluene and p-nitrophenol (Fluorescence response time < 1 sec , and the LOD for nitrobenzene, p-nitrophenol and p-nitrotoluene reached an impressive 349 ppb, 22 ppb and 98 ppb, respectively). Combined with theoretical calculations, we elucidated in detail the fluorescence quenching response mechanism of the LYH-HPTS towards nitroaromatic. Additionally, we also constructed fluorescent paper sensor, which effectively transformed the LYH-HPTS from theoretical detection to device application. The LYH-HPTS material is not only simple to synthesize, cost-effective and stable, but also has the features of fast response, excellent sensitivity and selectivity, and good reproducibility, which provides a new approach for the rapid and accurate detection of nitroaromatic. [ABSTRACT FROM AUTHOR]

This paper explored the in vitro inhibitory mechanism of polyphenol-rich rose extracts (REs) from an edible rose flower against α-glucosidase using multispectral and molecular docking techniques. Results showed that REs had an inhibitory effect on α-Glu activity (IC50 of 1.96 μg/mL); specifically, the samples pretreated by tri-frequency ultrasound (20/40/60 kHz) exhibited a significantly (p < 0.05) stronger inhibitory effect on α-Glu activity with an IC50 of 1.33 μg/mL. The Lineweaver–Burk assay indicated that REs were mixed-type inhibitors and could statically quench the endogenous fluorescence of α-Glu. REs increased the chance of polypeptide chain misfolding by altering the microenvironment around tryptophan and tyrosine residues and disrupting the natural conformation of the enzyme. Molecular docking results showed that polyhydroxy phenolics had a high fit to the active site of α-Glu, so REs with high polymerization and numerous phenolic hydroxyl groups had a stronger inhibitory effect. Therefore, this study provides new insights into polyphenol-rich REs as potential α-glucosidase inhibitors. [ABSTRACT FROM AUTHOR]

Two pyrrolo-based compounds, 1H-pyrrolo[3,2-b]pyridine-3-carboxylic acid (L1) and 1H-pyrrolo[3,2-c]pyridine-4-carboxylic acid (L2), were employed for the detection of bovine serum albumin (BSA) by UV-Vis and fluorescence spectroscopic methods in phosphate buffer solution (pH = 7). In the presence of L1 and L2, the fluorescence emission of BSA at 340 nm was quenched and concomitantly a red-shifted emission band appeared at 420 nm (L1)/450 nm (L2). The fluorescence spectral changes indicate the protein-ligand complex formation between BSA and L1/L2. An isothermal titration calorimetry (ITC) experiment was conducted to determine the binding ability between BSA and L1/L2. The binding constants are found to be 4.45 ± 0.22 × 104 M−1 for L1 and 2.29 ± 0.11 × 104 M−1 for L2, respectively. The thermodynamic parameters were calculated from ITC measurements (i.e. ∆rH = −40 ± 2 kcal/mol, ∆rG = −4.57 ± 0.22 kcal/mol and −T∆rS = 35.4 ± 1.77 kcal/mol), which indicated that the protein-ligand complex formation between L1/L2 with BSA is mainly due to the electrostatic interactions. The protein-ligand interactions were studied by performing molecular docking. Further, the antibacterial assay of L1 and L2 was conducted against gram-positive and gram-negative bacterial strains in an effort to address the difficulties caused by the co-occurrence of antimicrobial and multidrug-resistant bacteria. E. coli and S. aureus were significantly inhibited by L1 and L2. The L1 exhibits 13, 12 and 15 mm, whereas L2 exhibits a 2, 3 and 5 mm zone of inhibition against S. aureus, S. pyogenes and E. coli, respectively. In silico molecular docking of L1 and L2 was performed with bacterial DNA gyrase to establish the intermolecular interactions. Finally, the in vitro cytotoxicity activities of the ligands L1 and L2 have been carried out using drosophila. [ABSTRACT FROM AUTHOR]

Lithium‐ion batteries are currently the most widely used electrochemical energy storage devices. However, the most used graphite anode faces severe lithium plating issues when charging at low temperatures or high rates, leading to battery's capacity decay and even safety concerns. Therefore, visually and quantitatively detecting lithium plating is extremely important to analyze battery's performances. Here a convenient, rapid‐response, visual, and semi‐quantitative technique, namely fluorescence probe, is put forward to visually and quantitatively detect lithium plating on graphite anodes. A commercially available aggregation‐induced emission (AIE) molecule (4′‐hydroxychalcone) is introduced as a probe. The hydroxyl group of 4′‐hydroxychalcone can rapidly and sensitively react with plated lithium, instantaneously emerging an intensive yellow fluorescence within seconds; while 4′‐hydroxychalcone undergoes fluorescence quenching when directly contacting with graphite. Based on this, not only the uneven distribution of plated lithium on graphite anodes can be simply and clearly visualized and detected after being charged at low temperatures or high rates, but also the semi‐quantitative relationship between fluorescence intensity and the amount of plated lithium can be well established. Therefore, this work puts forward a practical solution for analyzing lithium plating on graphite anodes, offering a practical approach for failure analysis of lithium‐ion batteries used in various scenarios. [ABSTRACT FROM AUTHOR]

Covalent Organic Frameworks (COFs) exhibit a range of exceptional attributes, including notable porosity, outstanding stability, and a precisely tuned π‐conjugated network, rendering them highly promising candidates for fluorescence sensors applications. In this study, the synthesis of two emissive hydrazone‐linked COFs designed for hydrazine detection is presented. The partially conjugated structure of the hydrazone linkage effectively weakens the fluorescence quenching processes induced by aggregation. Additionally, the incorporation of flexible structural components further reduces conjugation, thereby enhancing luminescent efficiency. Remarkably, these COFs possess a significant abundance of heteroatoms, enabling distinctive interactions with hydrazine molecules, which in turn results in exceptional selectivity and sensitivity for hydrazine detection. The detection limit of these COFs reaches the nanomolar range, surpassing all previously reported COFs, thereby underscoring their superior performance in chemical sensing applications. [ABSTRACT FROM AUTHOR]

ABSTRACT Instant and accurate detection of 3‐nitrotyrosine (3‐NT) biomarker is an important but challenging task in clinical diagnosis, treatment, and monitoring of diseases. Herein, this work reported a Zn (II)–based metal–organic framework (MOF) {[Zn2(BDPT)(DIMB)]}n, denoted as Zn‐BDPT, synthesized by solvothermal method using bis(3,5‐dicarboxyphenyl)terephthalamide (H4BDPT) and 1,4‐di(1H‐imidazol‐1‐yl)butane (DIMB). Neighboring [Zn (COO)2] clusters were connected by BDPT4− units and DIMB to form a (2,4,4)‐connected three‐dimensional (3D) architecture. X‐ray powder diffraction (PXRD) and thermogravimetric (TGA) experiments indicated that Zn‐BDPT had good purity and stability. Zn‐BDPT could selectively and rapidly recognize 3‐NT in an aqueous environment. For rapid economic detection of 3‐NT in actual samples, mixed‐matrix membranes (MMMs) based on Zn‐BDPT were successfully prepared and named Zn‐BDPT@PMMA. The addition of 3‐NT under the UV lamp displayed an evident visible fluorescence quenching effect. Quantitative titration analysis of Zn‐BDPT@PMMA in real serum sample obtained the Ksv value of 1.13 × 104 M−1 and a limit of detection (LOD) of 0.17 μM. This report demonstrated that MOF‐based MMMs could be used as ideal candidate for luminescent probe in actual application. [ABSTRACT FROM AUTHOR]

ABSTRACT The antimicrobial, antitumor and antioxidant potential of Co(II), Cu(II), Mn(II), Ni(II), Pd(II), and Pt(II) complexes with 2‐(((2‐chloro‐5‐(trifluoromethyl)phenyl)imino)methyl)phenol HL ligand was investigated. A molecular docking study was carried out to estimate the predicted binding affinity of the compounds to protein targets involved in proliferative and bacterial activities. Fluorescence quenching studies and synchronous spectra were used to examine the metal complexes interactions with CT‐DNA and BSA protein. The DNA binding study have revealed that the complexes are capable of binding with DNA via intercalative mode. The antimicrobial activity of the ligand and metal complexes was studied against three Gram‐positive bacteria, two Gram‐negative bacteria, and three strains of fungi. The best antibacterial effect was demonstrated by the Pt(II) complex on the Staphylococcus aureus strain, and as for the inhibitory effect on fungi, it was stronger on the Candida albicans strain after treatment with the Co(II) complex. The in vitro antiproliferative activity of ligand and complexes was analyzed using MTT, Annexin V/PI, and cell cycle assays. The in vitro results showed that, except for Pd(II) complex, where slight effects were observed, the MCF‐7 line was resistant to the activity of the complexes. In the case of A549 cells, Cu(II) and Pd(II) complexes showed a dose‐dependent antitumor activity, confirmed by both the Alamar blue and the Annexin V/PI analysis. Finally, the antioxidant activity of the compounds was examined by ABTS and DPPH methods. Antioxidant investigation showed that the Ni(II) complex possesses a remarkable ability to trap the cation of the ABTS+ radical (IC50 value 9.35 μM). [ABSTRACT FROM AUTHOR]

Triple negative breast cancer (TNBC) is known for its heterogeneous nature and aggressive onset, limited unresponsiveness to hormone therapies and immunotherapy as well as high likelihood of metastasis and recurrence. Since no targeted standard treatment options are available for TNBC, novel and effective therapeutic targets are urgently needed. Ion channels have emerged as possible novel therapeutic candidates for cancer therapy. We previously showed that GABAA β3 subunit are expressed at higher levels in TNBC cell lines than non-tumorigenic MCF10A cells. GABAA β3 subunit knockdown causes cell cycle arrest in TNBC cell lines via decreased cyclin D1 and increased p21 expression. However, it is not known if the upregulated GABAAR express at the cell-surface in TNBC and mediate Cl- flux. Cl- ions are known to play a role in cell-cycle progression in other cancers such as gastric cancer. Here, using surface biotinylation and (N-(Ethoxycarbonylmethyl)-6-Methoxyquinolinium Bromide) MQAE-dye based fluorescence quenching, we show that upregulated GABAAR are on the cell-surface in TNBC cell lines and mediate significantly higher chloride (Cl-) flux as compared to non-tumorigenic MCF10A cells. Moreover, this GABAAR mediated Cl- flux can be modulated by pharmacological agents and is decreased in TNBC cells with GABAA β3 subunit knockdown. Further, treatment of TNBC cells with bicuculline, a GABAAR antagonist reduced cell viability in TNBC cells Overall, these results point to an unexplored role of GABAAR mediated Cl- flux in TNBC. [ABSTRACT FROM AUTHOR]

Over the past few decades, huge number of mesoporous materials have been synthesized by using supramolecular assembly of ionic/non‐ionic surfactants as structure‐directing agents (SDAs). Here, we report a facile synthetic strategy to fabricate self‐assembled SnO2 nanoparticles with well‐defined nanocrystalline spherical morphology and mesoporosity using sodium salicylate as a SDA and stabilizing agent. The mesophases of the materials were investigated by powder X‐ray diffraction, TEM and N2 sorption studies. TEM results show that the mesopores are formed by the assembly of ultrasmall SnO2 NPs with broad range of interparticle voids and N2 sorption studies agreed well with this TEM data. This synthesis strategy facilitated the generation of SnO2 NPs with increased surface area and pores of nanoscale dimensions with a large number of exposed surface‐active sites. The photoinduced electron transfer in these materials was investigated by the fluorescence quenching study with pyranine, which suggested the presence of surface Lewis basicity. The materials showed excellent catalytic activity for the synthesis of β‐nitroaldol through the reaction of benzaldehyde and nitromethane. The heterogeneous nature of the catalyst could be attributed to the high surface area, presence of numerous surface active sites, and structural robustness of the self‐assembled SnO2 nanostructure. The catalysts exhibited negligible loss in activity after several catalytic cycles. [ABSTRACT FROM AUTHOR]

This study introduces an innovative approach for the real-time and efficient detection of alkaline phosphatase (ALP) activity, using a calcein fluorescence probe and leveraging the static quenching properties of calcein fluorescence by Ce3+ metal ions. In this method, calcein serves as the signal element, with its fluorescence effectively preserved through energy transfer or charge transfer when coordinated with Ce3+. Conversely, ALP catalyzes the phosphopeptide substrate to generate a substantial amount of Pi, preventing calcein fluorescence quenching due to the higher affinity between Pi and Ce3+ compared with that between calcein and Ce3+. The fluorescence intensity ratio (F-F0/F0) exhibited excellent linearity, facilitating sensitive ALP detection. The proposed ALP detection method covers a range from 0 to 1.4 mU/mL (R2 = 0.9942), with the limit of detection at 0.069 mU/mL (S/N = 3). Additionally, this method was successfully applied for detecting ALP in serum samples and studying its inhibitors. This research introduces a novel clinical diagnosis approach for ALP sensing while broadening the potential applications of calcein. [ABSTRACT FROM AUTHOR]

A photoluminescent‐based "Turn On → Off → On" technique was adopted for a toxic, heavy metal ion detection, that is, specifically chromium (VI) and a pharmaceutically relevant ascorbic acid molecule. Metal‐free, environmentally benign, and fluorescent carbon dots, a potential vehicle for spectrofluorometric detection, were successfully deployed as sensors. Carbon dots synthesized from citric acid and sulfanilamide conserve the fragments of the precursor molecule on the surface. Zeta potential measurement evidenced the positively charged carbon nanoparticles physically interact with the Cr(VI)/Cr2O72− in acidic pH, resulting in a remarkable quenching in net fluorescence. Thorough studies revealed that the static quenching and inner filter effect were responsible for the reduction in fluorescence intensity. We have demonstrated a new rapid (in seconds) detection platform for Cr(VI) and ascorbic acid. [ABSTRACT FROM AUTHOR]

We have synthesized two dyads (dyad 1 and 2) comprising of tetraarylpyrrolo[3,2‐b]pyrrole (TAPP) and BODIPY. In dyad 1, two BODIPYs are directly connected with TAPP moiety whereas in dyad 2, BODIPYs are connected through phenylethynyl linkers. TAPP is a blue energy donor which is easy to synthesize and functionalize as compared to other well‐known blue energy donors like pyrene, perylene etc. This is the first report of using TAPP as an energy donor in BODIPY based dyad molecules. Complete quenching of TAPP fluorescence in the dyads suggests fast energy transfer from TAPP to BODIPY unit (ETE~99.9 %). Ultrafast fluorescence and transient absorption spectroscopic studies of dyad 1 showed TAPP to BODIPY energy transfer in 125 fs (kET=8.0×1012 s−1) which is one of the fastest energy transfer events in BODIPY based dyad reported so far. Whereas, in dyad 2, energy transfer is almost four times slower (480 fs, kET=2.1×1012 s−1). These results were rationalized by theoretical Förster formulations. This study shows that suitably matched optical properties of TAPP and BODIPY dyes along with their easy syntheses will be the key to develop highly efficient energy transfer systems in future for multiple applications. [ABSTRACT FROM AUTHOR]

Carbon dots (CDs) derived from mandarin peel biochar (MBC) at different pyrolysis temperatures (200, 400, 600, and 800 °C) have been synthesized and characterized. This high-value transformation of waste materials into fluorescent nanoprobes for environmental monitoring represents a step forward towards a circular economy. In this itinerary, CDs produced via one-pot hydrothermal synthesis were utilized for the detection of copper (II) ions. The study looked at the spectroscopic features of biochar-derived CDs. The selectivity of CDs obtained from biochar following carbonization at 400 °C (MBC400-CDs towards various heavy metal ions resulted in considerable fluorescence quenching with copper (II) ions, showcasing their potential as selective detectors. Transmission electron microscopic (TEM) analysis validated the MBC-CDs' consistent spherical shape, with a particle size of <3 nm. The Plackett–Burman Design (PBD) was used to study three elements that influence the F0/F ratio, with the best ratio obtained with a pH of 10, for 10 min, and an aqueous reaction medium. Cu (II) was detected over a dynamic range of 4.9–197.5 μM and limit of detection (LOD) of 0.01 μM. Validation testing proved the accuracy and precision for evaluating tap and mountain waters with great selectivity and no interference from coexisting metal ions. [ABSTRACT FROM AUTHOR]

The precise and effective detection of neurotransmitters (NTs) is crucial for clinical investigation of neuronal processes, and timely monitoring of NT‐related chronic diseases. However, sensitive detection of specific NT with unprecedented selectivity is highly challenging due to similarities in chemical and electronic structures of various interfering neurochemicals. Herein, an anionic conjugated polyelectrolyte Poly[(9,9‐bis(4'‐sulfonatobutyl)fluorene‐co‐alt‐1,4‐phenylene) sodium], PFPS was rationally designed and synthesized for amplified detection and point‐of‐care (PoC) determination of monoamine neurotransmitter, serotonin (5‐Hydroxy tryptamine or 5‐HT, also diagnostic biomarker of carcinoid tumor) in human blood plasma. The PFPS displayed a remarkable sensing response with an exceptionally high fluorescence quenching constant of 1.14×105 M−1 and an ultralow detection limit of 0.67 μM or 0.142 ppm, much below the clinical range. Furthermore, a smartphone‐enabled portable platform was constructed for real‐time onsite detection of 5‐HT by quantification of visual fluorescence response of PFPS into RGB values using a color recognizer android application. The smartphone platform could be readily applied for convenient, non‐invasive PoC testing of 5‐HT levels in complex biological fluids accurately and is expected to revolutionize clinical diagnosis and personalized health care devices. [ABSTRACT FROM AUTHOR]

ABSTRACT N′‐(2‐Fluorobenzoyl)benzo[d]thiazole‐2‐carbohydrazide (OFBBTCH, HL) and its chelates with Co(II) and Ni(II) have been synthesized and characterized by elemental analysis, liquid chromatography‐mass spectrometry (LC–MS), Fourier transform infrared spectroscopy (FT‐IR), ultra‐violet visible (UV–vis), nuclear magnetic resonance (NMR) spectroscopy, thermogravimetric analysis (TGA), and powder X‐ray diffraction. The conductance measurements reveal that the chelates are non‐electrolytic, and the spectral analysis indicates octahedral geometry of the chelates. The kinetic and thermodynamic parameters were obtained by Coats–Redfern relations, which shows positive Gibbs's free energy and negative entropy for both chelates. The equilibrium studies carried out by pH‐metry revealed the dissociation constant (pKa) of OFBBTCH as 8.13 and the formation of 1:1 and 1:2 Co(II)‐L and Ni(II)‐L complexes in solution. The CT‐DNA binding studies carried out by electron absorption, fluorescence quenching, steady state emissions and viscosity studies revealed hyperchromism and groove binding for HL and chelates. The Kb values calculated from electron absorption studies are 2.4 × 106, 4 × 106, and 9 × 106 M−1, from the fluorescence quenching studies Ksv values are 0.1722, 0.278, and 0.748 M−1, and Kapp values are 5.9 × 104, 1.3 × 105, and 2.9 × 105 M−1 for HL, Co(II)‐OFBBTCH and Ni(II)‐OFBBTCH, respectively. Bovine serum albumin (BSA) and human serum albumin (HSA) binding interactions were carried out by electron absorption and fluorescence quenching studies. The light switching properties of the chelates, the hydrolytic and oxidative cleavage of CT‐DNA, and the antioxidant properties were evaluated. Anti‐microbial studies carried out by pour plate method showed high activity for Ni(II)‐OFBBTCH chelate. Cytotoxicity of the compounds was performed for HeLa and MCF cell lines by MTT assay. Molecular docking studies revealed the docking of HL and Co(II)‐HL at the minor groove, and Ni(II)‐HL was docked at the major groove with hydrogen bonding. [ABSTRACT FROM AUTHOR]

Complex formation in aqueous solutions of human serum albumin (HSA) was studied with the medical drug curcumin, using the methods of UV absorption, emission, and excitation of fluorescence, the Stern equation (Vollmer, Hill, Foerster, and Van-Hoff), and computer modeling. It was established that the heteroassociation in the HSA-Cur system is realized due to the formation of stable complexes in the ground state, mainly due hydrophobic interaction in binding sites I and II. [ABSTRACT FROM AUTHOR]

ABSTRACT The human papillomavirus (HPV) 33 is a high‐risk strain that causes lesions with potential cancerous outcomes. Its E2 protein regulates the viral protein transcription and life cycle maintenance. The DNA binding domain (DBD) of the E2 protein plays a crucial role in the viral life cycle. The DBD region of the E2 protein is particularly interesting for targeting and finding potential inhibitors to inhibit its function or dimerization. Given the limited research on HPV 33 and its proteins, the present work delved into the interaction of two natural polyphenolic compounds, resveratrol, and baicalein, with the E2 DBD of HPV 33 using biophysical and in silico studies. Fluorescence studies of the E2 DBD‐polyphenol complexes showed fluorescence quenching with a binding constant of the order of 106 M−1. Circular dichroism data reveal conformational changes upon binding with the polyphenols, possibly due to distinct binding sites of the E2 DBD. Differential scanning calorimetry exhibited higher melting temperatures for the two complexes than alone DBD, suggesting the complexes' stability. ITC experiment suggested favorable binding reactions with kd values in the micromolar range. Molecular docking and dynamic simulation studies revealed that the resveratrol binds to the helical region and baicalein near the central dimeric interface of E2 DBD with a good binding affinity, forming a stable protein‐ligand complex during the run of 100 ns simulation. Therefore, the current study identifies both polyphenolic compounds as promising candidates for potential antiviral drug development. [ABSTRACT FROM AUTHOR]

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In recent years, lead-containing perovskite quantum dots (PQDs) have sparked a great deal of research in sensing applications as a result of their exceptional optoelectronic characteristics. However, due to their poor stability in ambient air and polar solvents such as water, they are not suitable as probes to detect analytes under aqueous conditions. The present study introduces a rapid and simple fluorescent approach for the sensing of bilirubin (BR) using ultrasonication-assisted synthesis of ethylenediaminetetraacetic acid functionalized CsPbBr3 PQDs (EDTA@CsPbBr3 PQDs) as optical nanoprobes. The as-prepared EDTA@CsPbBr3 PQDs displayed intense green fluorescence under UV light (365 nm) with excellent water stability. The fluorescence emission intensity (at 525 nm) of EDTA@CsPbBr3 PQDs was drastically decreased with the introduction of BR via an inner filter effect mechanism. The developed method for the assay of BR exhibited a broad linear range of concentration (0.05–25 μM) and low limit of detection (15.94 nM) with good selectivity. This study could open a path for the fabrication of water-dispersed PQDs with selective identification of BR, which is essential for sensing applications. [ABSTRACT FROM AUTHOR]

Nitroaromatic explosive sensing plays a critical role in ensuring public security and environmental protection. Herein, we report 2‐pyridyl‐thiazolothiazole (pyTTz) integrated blue‐fluorescent π‐conjugated porous polymer nanosheets, NTzCMP and TzCMP for selective sensing of picric acid (PA) among nitrophenol explosives. Acid‐base interactions between PA and pyTTz of CMP lead to H‐bonding interactions, where the hydroxy group of PA engaged in weak H‐bonding interactions with pyridine and TTz of pyTTz moiety. This led to a strong fluorescence quenching of CMPs—such formation of ground state complex was supported by linear Stern‐Volmer quenching plots, unaltered excited state lifetimes, and detailed FTIR analysis of PA exposed CMPs. Interestingly, both CMPs exhibited an excellent response to smaller analytes such as o‐nitrotoluene compared to 2,4‐dinitrotoluene. Both NTzCMP and TzCMP CMPs exhibited high KSV values of 9×103 and 2.1×103 M−1 for PA and the corresponding limit of detection values were found to be 0.46 and 1.6 ppm, respectively. [ABSTRACT FROM AUTHOR]

The detection of explosive materials, particularly nitroaromatic compounds such as 2,4,6‐trinitrotoluene (TNT), is critical for public safety and national security. Existing detection methods often require complex instrumentation, limiting their applicability for real‐time or in‐field use. Fluorescent sensors, which offer rapid and sensitive detection through fluorescence quenching, present a promising alternative. This study evaluates the performance of two pentiptycene‐based polymers, P‐1 and P‐2, in detecting explosive vapors, with a specific focus on their behavior under high‐humidity conditions. P‐2, modified with triethylene glycol groups, demonstrated significantly increased hydrophilicity compared to the commonly studied P‐1, as confirmed by contact angle measurements. Spectroscopic analysis revealed a blue shift in P‐2's UV–Vis absorption and photoluminescence spectra, indicating electronic property changes due to structural modifications. The enhanced hydrophilicity of P‐2 enabled it to maintain stable sensing performance under moist conditions, showing less than a 10% reduction in sensitivity, compared to the 20% decrease observed in P‐1. This superior moisture resistance suggests that P‐2 is a more robust and practical sensor for explosive detection in environments with variable humidity levels. [ABSTRACT FROM AUTHOR]

Environmental‐friendly carbon dots (CDs) have found wide applications in the fields of white light emitting diode (WLED), chemical sensor, wide‐gamut display, etc. However, for the aggregation‐caused quenching (ACQ) effect, high dose of CDs immobilization generally suffers from the great fluorescence quenching, hindering their practical uses in many cases. In the present work, a one‐step microwave‐assisted microemulsion process is developed to prepare matrix‐free green CDs powders with absolute fluorescent quantum yield (QY) up to 48.34%. From dilute solution to matrix‐free powder, the QY of CDs decreases only about 20%, significant smaller than the sample prepared without surfactant (74%). Structural characterization and fluorescent lifetime measurements suggest that the passivation of hydrophobic long‐alkyl chains from surfactant Span‐80 is very key for their good solid‐state photoluminescence (PL). For the good solid‐state PL and various solvent‐compatibility, the CDs reported show promising applications in the fabrication of WLED and the measurement of water content of ethanol/water solution. This work provides a new idea to design and simply synthesize desirable CDs‐based luminescent materials with good solid‐state PL. [ABSTRACT FROM AUTHOR]

Cryptophytes are abundant and ubiquitous microalgae that constitute a major plastid source for kleptoplastidic ciliates and dinoflagellates. Despite their ecological significance, the understanding of their light preferences and photophysiology remains limited. Here, we provide a comprehensive study of the response of the haploid strain Teleaulax amphioxeia (Cr10EHU) to varying light irradiance. This strain is capable of growing under a wide range of irradiance levels, notably by finely tuning the different pigments bound to the membrane light‐harvesting proteins. Analysis of the luminal phycoerythrin content revealed remarkable flexibility, with phycoerythrin emerging as a pivotal protein facilitating acclimation to varying light levels. Detailed ultrastructure examinations unveiled that this adaptability was supported by the synthesis of large thylakoidal vesicles, likely enhancing the capture of green photons efficiently under low light, a phenomenon previously undocumented. Teleaulax amphioxeia Cr10EHU effectively regulated light utilization by using a cryptophyte state transition‐like process, with a larger amplitude observed under high growth irradiance. Furthermore, our results revealed the establishment of growth irradiance‐dependent non‐photochemical quenching of fluorescence, likely inducing the dissipation of excess light. This study underscores the particularities and the significant photoadaptability of the plastid of the haploid form of T. amphioxeia. It constitutes a comprehensive photophysiological characterization of the Cr10EHU strain that paves the way for future studies of the kleptoplastidy process. [ABSTRACT FROM AUTHOR]

Tracer based planar laser-induced fluorescence (PLIF) has emerged as a powerful in-situ measurement technique with a considerable spatial and temporal resolution for Internal combustion (IC) engines. In PLIF, the emitted fluorescence signals from a tracer molecule are processed to determine distribution of temperature, fuel, residual gases, etc. However, it is imperative to have a thorough understanding of the tracer physical properties and its fluorescence intensity dependencies on excitation wavelength, pressure, temperature and bath gas composition existing inside the combustor for accurate quantitative interpretation. This work consists of a series of two articles providing a detailed review of the existing literature of fluorescence characteristics of various molecules used as tracers in IC engine applications. Due to the overwhelming usage of organic compounds in IC engine environment, the work is restricted to them. Part A of this work is focussed on non-aromatic compounds whereas part B will focus on aromatics (toluene, anisole, naphthalene, 1-methylnaphthalene and fluoranthene). Due to a large energy gap between the excited singlet and triplet states of aromatics, they are highly sensitive to oxygen quenching effects than ketones. Absorption cross-section might increase or decrease with temperature but is insensitive to pressure changes. Fluorescence quantum yield of aromatics show a very strong reduction with increase in temperature but might either increase or decrease with increasing pressure. The pressure sensitivity is found to increase with the number of atoms in a bath gas molecule. Fluorescence spectra are found to undergo redshift with temperature which can be used to measure temperature using 2 colour thermometry. The large fluorescence quenching by oxygen can also be used to directly measure fuel–air ratio using FARLIF methodology. Towards the end several IC engine studies are reviewed to discuss various aspects of mixture formation and temperature distribution. [ABSTRACT FROM AUTHOR]

Gold-platinum (Au@Pt) nanozymes with high catalytic activity and stability were designed to improve the stability of the enzyme-linked immunosorbent assay (ELISA), and a two-mode signal output was used to enhance the sensitivity and confidence of the assay. This study reports the two-mode signal output based on Au@Pt nanozyme to catalyzed 3,3′,5,5′-tetramethylbenzidine (TMB) reaction. Oxidized 3,3′,5,5′-tetramethylbenzidine (ox-TMB) has wide absorption spectrum, providing excellent optical density capabilities and fluorescence quenching. The detection limits of imidacloprid were 0.88 μg/L and 1.14 μg/L in colorimetric and fluorescence modes, respectively. Multiple-mode strategy improves detection accuracy, increases the confidence of experimental results, and broadens detection modes. Two modes can meet the requirements of accurate and flexible multi-mode sensing in different application situations. [ABSTRACT FROM AUTHOR]

A novel kind of carbon dot (CD) was prepared by one-step hydrothermal microwave assisted method using l-tryptophan and l-tartaric acid as raw materials. Monodisperse poly(glycidyl methacrylate-co-ethylene glycol dimethacrylate) microspheres were utilized as the matrix, with praseodymium (Pr) ion (Pr3+) as the template, methacrylic acid as the functional monomer, and 5-amino-8-hydroxyquinoline (5-AHQ) acts as the ligand. A composite microsphere of ion-imprinted polymer (IIP) and CD (noted CD@IIP) was prepared by surface-initiated atom transfer radical polymerization (SI-ATRP). For comparison, IIP without CD (Pr-IIP) and non-imprinted polymer (NIP) were also prepared. Through static adsorption experiments, it was determined that the saturated adsorption amount of CD@IIP is 47.19 mg g−1, that of Pr-IIP is 54.49 mg g−1, while that of NIP is only 24.32 mg g−1. Dynamic adsorption experiments showed that the equilibrium of three kinds of materials was reached within 30 min. Particularly, CD@IIP could emit two fluorescence peaks at 325 nm and 421 nm under ultraviolet irradiation, and exhibited excellent selectivity and fluorescence quenching effect on Pr3+. The fluorescence response of Pr3+ in the range 0–400 μmol L−1 was determined by ratiometric fluorescence method, offering a two-stage model and robust linear regression coefficient. These results demonstrated that CD@IIP exhibited selective adsorption ability for Pr3+, and a sensitive, rapid and simple method for detection of Pr3+ was successfully developed. [ABSTRACT FROM AUTHOR]

A hydrothermal synthetic method is established to produce blue fluorescent Eu3+-doped niobium carbide MXene quantum dots (Eu3+-Nb2C MQDs). The synthesized Eu3+-Nb2C MQDs demonstrated a quantum yield of 20.61% and a maximum emission intensity at 405 nm. The as-prepared Eu3+-Nb2C MQDs acted as a sensor for the rapid and sensitive detection of hypoxanthine through fluorescence quenching, and of fluoxetine through fluorescence enhancement mechanisms. The emission peak of Eu3+-Nb2C MQDs at 405 nm exhibited a linear response for hypoxanthine and fluoxetine in the ranges of 0.5–25 µM and 0.125–2.5 µM, with detection limits of 15.0 and 3.7 nM, respectively. The newly developed probe was effectively used for the selective detection of hypoxanthine and fluoxetine in biofluids and pharmaceutical samples. Remarkably, the Eu3+-Nb2C MQDs exhibited minimal cytotoxicity towards A549 lung cancer cells and showed great potential as imaging agent for imaging of Saccharomyces cerevisiae cells. [ABSTRACT FROM AUTHOR]

Highly stable copper nanocluster (CuNCs) with aggregation-induced emission (AIE) properties was synthesized. α-, β-, and γ- MnO2 were utilized as quenchers, with CuNCs fluorescence quenching of 48.9%, 91.5%, and 96.6%, respectively. L-ascorbate-2-phosphate (AAP) was hydrolyzed by acid phosphatase (ACP), and ascorbic acid (AA) was formed. Then, MnO2 could be restored by AA, and the fluorescence of the CuNCs could be restored. An on–off–on detection platform with a high signal/noise ratio was constructed for the sensing of ACP. The fluorescence recovery rate of the CuNCs was related to the crystal forms of MnO2. Then, the equilibrium constants (K) for the reaction between AA and MnO2 were calculated to evaluate the reaction process. Compared with the K values of CuNCs/α-MnO2 and CuNCs/γ-MnO2, the K values for AA and β-MnO2 were maximum. The CuNCs/β-MnO2 system exhibited optimal fluorescence recovery for the sensitive detection of ACP. In the concentration range 0.005–0.06 U/mL, the detection limit was 0.0028 U/mL. The determination of serum ACP levels also revealed satisfactory results. This study provides novel insights into enhancing the sensitivity of the determination of quenchers in different crystal form. [ABSTRACT FROM AUTHOR]

A fluorescent probe based on ternary AgFeS2 quantum dots has been prepared for the design of ternary chalcogenides. The nanoparticles are synthesized with oleylamine as a stabilizer at a low temperature (particle size in the range of 2 to 3 nm) and they exhibit an intense blue emission in aqueous media. As for their internal structure, each nanoparticle's relative stoichiometric ratio (AgFe1.01S1.91) is very close to the theoretical value of 1:1:2. Their magnetic properties have been studied with a vibrating sample magnetometer and they have ferromagnetism between 4 K and 298 K (applied magnetic field ranging between −10,000 and 10,000 Oe). In the presence of iodide ions, the emission at 458 nm derived from AgFeS2 QDs has been observed to give rise to fluorescence quenching. The detection system is based on a static quenching process and morphological change between iodide ions and AgFeS2, which has a good linear range from 0 to 37.5 μmol/L, with a limit of detection of 0.99 μM. The nanoprobe responds within 30 s for the efficient detection of iodide. Such functional quantum dots will provide a powerful indicator in environmental and bio-sensing applications. [ABSTRACT FROM AUTHOR]

PDIA3 is a pleiotropic protein primarily located in the endoplasmic reticulum where it is involved in protein folding, catalyzing the formation, breakage, and rearrangement of disulfide bonds. PDIA3 is implicated in numerous pathologies such as cancer, inflammation, and neurodegeneration. Although punicalagin has been proven to be a highly promising PDIA3 inhibitor and can be used as target protein in glioblastoma, it does not have sufficient selectivity for PDIA3 and is a quite-large molecule. With the aim of finding punicalagin derivatives with a simplified structure, we selected punicalin, which lacks the hexahydroxy-diphenic acid moiety. Previous docking studies suggest that this part of the molecule is not involved in the binding with PDIA3. In this study we compared the ability of punicalin to bind and inhibit PDIA3 and PDIA1. Tryptophan fluorescence quenching and disulfide reductase activity (using both glutathione and insulin as substrates) were evaluated, demonstrating the ability of punicalin to bind and inhibit PDIA3 even to a lesser extent compared to punicalagin. On the other hand, punicalin showed a very low inhibition activity towards PDIA1, demonstrating a higher selectivity for PDIA3. Protein thermal shift assay evidenced that both proteins can be destabilized by punicalin as well as punicalagin, with PDIA3 much more sensitive. Additionally, punicalin showed a higher change in the thermal stability of PDIA3, with a shift up to 8 °C. This result could explain the presence of PDIA3 aggregates, evidenced by immunofluorescence analysis, that accumulate within treated cells and that are more evident in the presence of punicalin. The results here obtained show punicalin is able to bind both proteins but with a higher selectivity for PDIA3, suggesting the possibility of developing new molecules with a simplified structure that are still able to selectively bind and inhibit PDIA3. [ABSTRACT FROM AUTHOR]

Xero-halophytes are the salt-tolerant plants of dry habitats that adapt efficient strategies to endure extreme salt and water fluctuations. This study elucidated the adaptations related to PSII photochemistry, photoprotection, and photoinhibition in six C4 xero-halophytes (Atriplex stocksii , Haloxylon stocksii , Salsola imbricata, Suaeda fruticosa, Desmostachya bipinnata , and Saccharum griffithii) grown in their native habitats. Chlorophyll a fluorescence quenching measurements suggested that S. imbricata and H. stocksii maintained efficient PSII photochemistry by downregulating heat dissipation and keeping a high fraction of open PSII centres that indicates plastoquinone (PQ) pool oxidation. Fluorescence induction kinetics revealed that S. imbricata demonstrated the highest performance index of PSII excitation to the reduction of end electron acceptors. S. fruticosa sustained photochemical efficiency through enhanced dissipation of excess energy and a low fraction of open PSII centres, indicating PQ reduced state. The large light-harvesting antenna size, deduced from the chlorophyll a / b ratio in S. fruticosa apparently led to the superior performance index of PSII excitation to the reduction of intersystem electron carriers. A. stocksii retained more open PSII centres with responsive non-photochemical quenching to safely dissipate excess energy. Despite maintaining the highest pigment contents and stoichiometry, A. stocksii remained lowest in both performance indices. The grass species D. bipinnata and S. griffithii kept fewer PSII centres open during photoinhibition, as evidenced by downregulation of PSII operating efficiency. The results provide insights into the differential modulation of PSII photochemical efficiency through dynamic control of photoprotective energy dissipation, PQ pool redox states, and photoinhibitory shutdown in these xero-halophytes. Photochemical adaptations of six C4 xero-halophytes reveal diverse strategies to endure salt and water fluctuations in native habitats. Variations in photochemistry, photoprotection, and photoinhibition indicate modulation of PSII photochemical efficiency. Different xero-halophytes exhibit distinct mechanisms for maintaining photochemical efficiency through dynamic control of plastoquinone pool redox states, excess energy dissipation, and shutdown mechanisms in response to environmental challenges. [ABSTRACT FROM AUTHOR]