Fluorescence Properties Research Articles

Comment on 'Accumbens cholinergic interneurons dynamically promote dopamine release and enable motivation'.

Acetylcholine is widely believed to modulate the release of dopamine in the striatum of mammals. Experiments in brain slices clearly show that synchronous activation of striatal cholinergic interneurons is sufficient to drive dopamine release via axo-axonal stimulation of nicotinic acetylcholine receptors. However, evidence for this mechanism in vivo has been less forthcoming. Mohebi, Collins and Berke recently reported that, in awake behaving rats, optogenetic activation of striatal cholinergic interneurons with blue light readily evokes dopamine release measured with the red fluorescent sensor RdLight1 (Mohebi et al., 2023). Here, we show that blue light alone alters the fluorescent properties of RdLight1 in a manner that may be misconstrued as phasic dopamine release, and that this artefactual photoactivation can account for the effects attributed to cholinergic interneurons. Our findings indicate that measurements of dopamine using the red-shifted fluorescent sensor RdLight1 should be interpreted with caution when combined with optogenetics. In light of this and other publications that did not observe large acetylcholine-evoked dopamine transients in vivo, the conditions under which such release occurs in behaving animals remain unknown.

Direct Comparative Studies Revealing the Contribution of TADF Activity of Organic Emitters Towards Efficient Electrochemiluminescence.

Electrochemiluminescence (ECL) featuring thermally activated delayed fluorescence (TADF) properties has attracted considerable interest, showcasing their potential for 100% exciton harvesting, which marks a significant advancement in the realm of organic ECL. However, the challenge of elucidating the precise contribution of TADF to the enhanced ECL efficiency arises due to the lack of comparative studies of organic compounds with or without efficient TADF properties. In this study, we present four carbazole-benzonitrile (Cz-BN) molecules possessing similar chemical structures and comparable exchange energy (ΔEST). Despite their comparable properties, these compounds exhibited varying TADF efficiencies, warranting a closer examination of their underlying structural and electronic characteristics governing the optical properties. Consequently, intense ECL emission was only observed from 4CzBN with a remarkable TADF efficiency, underscoring the substantial difference in the ECL signal among molecules with comparable ΔEST and similar spectral properties but varying TADF activity.

Dual modulation of blue-fluorescent carbon dots for simultaneous detection of topotecan and pantoprazole.

This study introduces a novel approach for the simultaneous determination of topotecan (TOP) and pantoprazole (PNT), two drugs whose interaction is critical in clinical applications. The significance of this study originates from the need to understand the pharmacokinetic changes of TOP after PNT administration, which can inform necessary dose adjustments of TOP. To achieve this, nitrogen blue emissive carbon dots (B@NCDs) were produced and employed due to their unique fluorescent properties. When TOP is added to B@NCDs, it exhibits strong native fluorescence at 545 nm without influencing the B@NCDs' fluorescence at 447 nm. Conversely, PNT causes quenching of B@NCDs fluorescence, a property that enables the distinct detection of both drugs. The B@NCDs were fully characterized using different techniques, including ultraviolet-visible spectrophotometry, fluorescence analysis, X-ray diffraction (XRD), transmission electron microscopy (TEM), and FTIR spectroscopy. The proposed method demonstrated excellent linearity, selectivity, and sensitivity, with low detection limits (LOD, S/N = 3); 0.0016 μg mL-1 for TOP and 0.36 μg mL-1 for PNT. Applied to spiked rabbit plasma samples, this method offers a new approach for evaluating the pharmacokinetic interaction between TOP and PNT. It enables the determination of all pharmacokinetic parameters of TOP before and after coadministration with PNT, providing essential insights into whether dose adjustments are necessary. This research not only contributes to the field of drug monitoring and interaction studies but also exemplifies the potential of B@NCDs in complex biological matrices, paving the way for further pharmacological and therapeutic applications.

Deciphering the luminescence mechanism: Investigating ESIPT-attributed HPI2C molecule with coupled thermally activated delayed fluorescence and phosphorescence properties

Long persistent luminescence (LPL) including thermally activated delayed fluorescence (TADF) and phosphorescence is widely applied in luminogens. Recently, Pan et al. pioneered the discovery of TADF and phosphorescence in the HPI2C molecule by manipulating temperature in line with the excited-state intramolecular proton transfer (ESIPT) dynamics (J. Am. Chem. Soc. 2022, 144, 2726). They blazed a new trail to explore the switching mechanism between TADF and phosphorescence in single molecule. Nevertheless, luminescence mechanism for HPI2C cannot be explained solely through experimental means. Theoretically, we demonstrate that the ESIPT and photocyclization channel induced conical intersection processes facilitate the fluorescence quenching of the Enol* state. Moreover, we prove the cruciality of the T2 state in the TADF phenomenon involved in Keto* state and reconsider the mechanism of the dual phosphorescence. Our investigation is favorable to provide theoretical support for the design of the LPL materials based on the ESIPT-attributed molecules.

Studies on Various Taxonomic, Pharmacognostic and Phytochemical Properties of Sanchezia speciosa Leonard Acanthaceae

Sanchezia speciosa Leonard, Acanthaceae is used as ornamental plant. It used in folklore medicine in the management of pain, anti-microbial and insecticide. An investigation was carried out to evaluate the various taxonomic, pharmacognostic and phytochemical standards to ensure the identity, purity, safety and efficacy of the medicinal plant, S. speciosa. Various observations were recorded which included microscopy, micromeritics, fluorescence, chemomicroscopy, soluble extractive values, moisture contents and phytochemical analysis. The results indicated that the epidermal shapes were both polygonal on the adaxial and abaxial surfaces. Stomatal distribution was amphistomatic with anisocytic and diacytic stomata on the adaxial and abaxial surface, respectively. Stomatal index was 21.47% on the adaxial surface and 15.43% on the abaxial surface. Micromeritics results for the leaf powder were bulk volume of 25.33± 0.408, tapped volume of 19.00± 0.00, bulk density of 0.40± 0.006, tapped density of 0.53± 0.021, Hausner’s ratio of 1.34± 0.037, Carr’s index of 25.00± 2.550 and angle of repose of 43.07°. The micromeritics indicated a passable flow. The chemo microscopy indicated presence of lignin, mucilage and starch. Fluorescence properties showed different colours under different ultraviolet lights. The water-soluble, methanol-soluble, ethanol-soluble extractive values were 14.7% w/w, 4.3% w/w and 5.0% w/w, respectively. Moisture content was 8.5% w/w. Total ash, acid-insoluble and water-soluble ash values were 20.0 % w/w, 2.0% w/w and 4.2% w/w, respectively. GC-MS of methanol extract revealed the total of 39 phytochemicals with over 5 prominent peaks having higher area% which include hexadecanoic acid methyl ester (2.64%), 9,12,15-octadecatrienoic acid methyl ester (4.77%), phytol (9.98%), 9,12,15 octadecatrienoic acid (12.97%), Stigmasterol (2.00%) and Squalene (28.16%). Other compounds are glycerin (5.83%), n-hexadecanoic acid (2.85%) and 9 octadecenamide (2.18%). Many of them possess good pharmacological properties. The data generated from the present study would help to authenticate S. speciosa and also affirm its folklore use in traditional medicine which has potential for further development into drug product.

Palladium-Catalyzed Arylations towards 3,6-Diaryl-1,3a,6a-triazapentalenes and Evaluation of Their Fluorescence Properties

Methyl 4-(1,3a,6a-triazapentalen-3-yl)benzoate (TAP1) shows interesting properties as a small molecule fluorophore. In the search for post-functionalization methods, palladium-catalyzed arylation reactions were demonstrated. Direct CH arylation reactions of TAP1 with various aryl halides resulted in 3,6-diaryltriazapentalenes TAP4, although mostly in poor yields. Bromination of TAP1 followed by Suzuki coupling, on the other hand, requires a more delicate procedure, but gave arylated products with the same regiochemistry (TAP4) in moderate to good yields. The structure of 6-phenyltriazapentalene TAP4a was confirmed by crystallographic analysis. In addition, the effect of the C6 arylation on the fluorescent properties of 3-aryl-1,3a,6a-triazapentalenes was studied in dichloromethane at room temperature and in 2-methyltetrahydrofuran at 77K, while the photophysical properties of two saponified derivatives were measured in acetonitrile.

The Optimization of the One-Pot Synthesis of Au@SiO2 Core–Shell Nanostructures: Modification with Dansyl Group and Their Fluorescent Properties

This work describes the optimization of the one-pot synthesis of fine core–shell nanostructures based on nanogold (Au NPs) and silica (SiO2). The obtained core–shell nanomaterials were characterized by Transmission Electron Microscopy (TEM and by the method of spectroscopes such as UV–Vis Spectroscopy and Fourier Transform Infrared Spectroscopy (FT-IR). In addition, the measurement of the zeta potential and size of the obtained particles helped present a full characterization of Au@SiO2 nanostructures. The results show that the influence of reagents acting as reducers, stabilizers, or precursors of the silica shell affects the morphology of the obtained material. By controlling the effect of the added silica precursor, the thickness of the shell can be manipulated, the reducer has an effect on the shape and variety, and then the stabilizer affects their agglomeration. This work provides also a new approach for Au@SiO2 core–shell nanostructure preparation by further modification with dansyl chloride (DNS–Cl). The results show that, by tuning the silica shell thickness, the intensity of the fluorescence spectrum of Au@SiO2–(CH2)3–NH–DNS nanocomposite is about 12 times higher than that of DNS–Cl.

Suprahydrostable ultrasmall hybrid cuprous halide with pseudo-net protector for wireless light-triggered rewritable transient display and dynamically recoverable encryption

Zero-dimensional (0D) organic-inorganic hybrid metal halides (OIHMHs) are receiving significant attention due to their exceptional photovoltaic properties. However, their applications are restricted by their inferior water stability and undesired particle size. Herein, we synthesized suprahydrostable ultrasmall 0D OIHMHs with an average size of ∼3.4 nm, named (TOA)CuBr2 for the first time. (TOA)CuBr2 nanocrystals exhibit bright fluorescence attributed to self-trapping excitons and demonstrated by density functional theory calculations. It is worth emphasizing that (TOA)CuBr2 displays excellent reversible photoluminescence (PL) response to UV light, temperature, and acid/alkali simultaneously, especially to acid/alkali. The underlying mechanism of the reversibility properties is explained and the reversible PL switch is developed by utilizing the acid/alkali responsive property. Moreover, it is the first demonstration of a real-time rewritable transient display based on 0D OIHMHs with “writing/self-erasing/rewriting” capability under wireless near-infrared light. In addition, encrypted strips prepared by in-situ growth of (TOA)CuBr2 in polydimethylsiloxane show quite stable fluorescence properties in various scenarios. Dynamically recoverable encryption systems are also designed by taking full advantage of the material’s multi-response characteristics. Our work provides a strategy for synthesizing suprahydrostable ultrasmall OIHMHs, which will lay a solid foundation for developing their multi-scenario applications in the future.

3D microscaffolds with triple-marker sensitive nanoprobes for studying fatty liver disease in vitro.

Non-alcoholic fatty liver disease (NAFLD) is a heterogeneous condition that encompasses a wide range of liver diseases that progresses from simple hepatic steatosis to the life-threatening state of cirrhosis. However, due to the heterogeneity of this disease, comprehensive analysis of several physicochemical and biological factors that drive its progression is necessary. Therefore, an in vitro platform is required that would enable real-time monitoring of these changes to better understand the progression of these diseases. The earliest stage of NAFLD, i.e. hepatic steatosis, is characterised by triglyceride accumulation in the form of lipid vacuoles in the cytosol of hepatocytes. This fatty acid accumulation is usually accompanied by hepatic inflammation, leading to tissue acidification and dysregulated expression of certain proteases such as matrix metalloproteinases (MMPs). Taking cues from the biological parameters of the disease, we report here a 3D in vitro GelMA/alginate microscaffold platform encapsulating a triple-marker (pH, MMP-3 and MMP-9) sensitive fluorescent nanoprobe for monitoring, and hence, distinguishing the fatty liver disease (hepatic steatosis) from healthy livers on the basis of pH change and MMP expression. The nanoprobe consists of a carbon nanoparticle (CNP) core, which exhibits intrinsic pH-dependent fluorescence properties, decorated either with an MMP-3 (NpMMP3) or MMP-9 (NpMMP9) sensitive peptide substrate. These peptide substrates are flanked with a fluorophore-quencher pair that separates on enzymatic cleavage, resulting in fluorescence emission. The cocktail of these nanoprobes generated multiple fluorescence signals corresponding to slightly acidic pH (blue) and overexpression of MMP-3 (green) and MMP-9 (red) enzymes in a 3D in vitro fatty liver model, whereas no/negligible fluorescence signals were observed in a healthy liver model. Moreover, this platform enabled us to mimic fatty liver disease in a more realistic manner. Therefore, this 3D in vitro platform encapsulating triple-marker sensitive fluorescent nanoprobes would facilitate the monitoring of the changes in pH and MMP expression, thereby enabling us to distinguish a healthy liver from a diseased liver and to study liver disease stages on the basis of these markers.

Fluorescence Sensors for the Detection of L-Histidine Based on Silver Nanoclusters Modulated by Copper Ions

In this study, Cu2+ modulated silver nanoclusters were constructed for the turn-on, label-free detection of L-histidine. Six Ag NCs protected by oligonucleotides (DNA-Ag NCs) were tested in a series of experiments. Finally, A-DAN-Ag NCs were chosen as the best candidate due to their excellent fluorescent properties. The fluorescence of A-DAN-Ag NCs was quenched using Cu2+ through energy or electron transfer. However, quenched fluorescence could be restored dramatically in the presence of L-histidine due to Cu2+ liberation from A-DAN-Ag NCs and because of the chelation between the imidazole group of L-histidine and Cu2+. The proposed sensor exhibited high selectivity towards L-histidine over other amino acids, with a limit of detection (LOD) of 0.096 μM ranging from 0 to 8 μM. The proposed sensor succeeded in detecting L-histidine in diluted human urine. Therefore, the sensor has promising practical applications in biological systems.

Tetrazole-functionalized Organoboranes Exhibiting Dynamic Intramolecular N→B-Coordination and Cyanide-selective Anion Binding.

Starting from two different cyano-functionalized organoboranes, we demonstrate that 1,3-dipolar [3+2] azide-nitrile cycloaddition can serve to generate libraries of alkyl-tetrazole-functionalized compounds capable of intramolecular NàB-Lewis adduct formation. Due to the relatively low basicity of tetrazoles, structures can be generated that exhibit weak and labile NàB-coordination. The reaction furnishes 1- and 2-alkylated regio-isomers that exhibit different effective Lewis-acidities at the boron centers, and vary in their optical absorption and fluorescence properties. Indeed, we identified derivatives capable of selectively binding cyanide over fluoride, as confirmed by 11B NMR. This finding demonstrates the potentialities of this synthetic strategy to systematically fine-tune the properties of lead structures that are of interest as chemical sensors.

A Lead‐Free Tin Organic‐Inorganic Hybrid Material with Reversible Phase Transition and Fluorescent Properties

AbstractThis article reports a novel lead‐free phase‐transition material (C8H10ClN)2SnCl6 (1), which undergoes a high‐temperature phase change at close to 377 K. The multi temperature powder X‐ray diffraction (PXRD) also confirmed the phase transition occurred in compound 1. Significantly, compound 1 produces light emission at 452 nm. Variable temperature fluorescence studies indicate that the spectral emission maximum of compound 1 remains substantially fixed at 452 nm with increasing temperatures, implying the presence of a certain degree of photoluminescence stability in compound 1. Furthermore, compound 1 is characterized by exceptional semiconductor attributes, possessing a band gap of 3.76 eV. This pioneering study presents an innovative option for optimizing the growth and practical implementation of Sn (IV)‐based organic‐inorganic hybrid perovskite phase‐transition materials, and offers a strategic avenue to create novel lead‐free, eco‐friendly materials.

Poly-3,4-dihydroxybenzylidenhydrazine, a different analogue of polydopamine

Abstract In this article, 3,4-dihydroybenzylidenehydrazine is synthesized for the first time, and its properties as a dopamine analogue for polymerization are investigated. Using an oxidative polymerization reaction, the reaction mechanism as well as the coating ability of the new polymer is determined and compared to that of polydopamine. The polymerization reactions were performed in a mixture of methanol–water with NaIO4 as an oxidation reagent. The polymer was used as a coating on both glass surfaces with a thickness of ∼5 nm as determined by AFM, as well as on TiO2 nanoparticles. For the latter, SEM/TEM and the pH-dependent variation of zeta potential were measured. As a free polymer, poly-3,4-dihydroxybenzylidenhydrazine was investigated by UV-Vis, ss-NMR, and FTIR, and a variety of monomeric units were found in the polymer matrix. The solubility in methanol or DMSO of the monomer and the slight solubility of the polymer allowed us to study the fluorescence and cyclic voltammetry properties for both the monomer and polymer.

Carbon Dots Derived from Jaggery Via Direct Heating: A Sensitive Platform for Ferric Ion Fluorescent Sensing

AbstractPhotoluminescent carbon dots (CDs) have greatest potential in fluorescence sensing, energy, bioimaging and environmental pollutant sensing. Heteroatom doping have dramatically enhanced fluorescent properties and stability of CDs. In this work, sulfur doped carbon dots (DCDs) using jaggery as carbon precursor through direct heating method at 180 °C. The synthesized DCDs were characterized through XRD, FTIR, XPS, TEM, Fluorescence and UV‐Visible spectroscopic techniques. The DCDs have 9 nm particle size with amorphous nature and surface decorated with −OH, C−S, C=O functional groups on surface because of contribution of major element like C, O, and S elements. The DCDs showing bright blue emission having 360 nm excitation and 460 nm emission wavelength. Further, the DCDs were employed for metal ion sensing and it selectively detects Fe3+ metal ion with 1.92 μg/mL of detection and 5.84 μg/mL limit of quantification. The experiment follows static quenching mechanism which is confirmed by fluorescence life time experiment. This low‐cost, time effective fluorescent sensitive carbon dots have potential application in environmental pollution control, biomedical and forensic applications.

Structure, properties and application of Tb3+ doped CaMO4 (M: W, Mo) phosphors prepared by solid-state double exchange method

In this paper, nanoscale Tb3+ doped CaMO4 (M: W, Mo) were prepared by a facile and mild solid-state double exchange method. The structures, morphologies, temperature stability and fluorescence properties of the obtained phosphors were characterized by XRD, SEM, Raman, FT-IR and PL, respectively. Based on the phosphors, the luminescent films and LED optical devices were fabricated. In addition, the detections of Cr2O72− and 4-nitrophenol (4-NP) were successfully achieved. The results showed that the detecting platform have good selectivity and sensitivity. Therefore, Tb3+ doped CaMO4 (M: W, Mo) phosphors could be an eminent candidate for versatile application prospect.

SYNTHESIS OF NEW BODIPY HYDRAZIDE FLUORESCENT PROBES FOR THE DETECTION OF CARBONYLATED PROTEINS GENERATED BY OXIDATIVE STRESS.

Oxidative stress is a cellular disorder implicated in various severe diseases and redox biology and represents an important field of research for the last decades. One of the major consequences of oxidative stress is the carbonylation of proteins, which is also a reliable marker to assess protein oxidative modifications. Accumulation of carbonylated proteins has been associated with aging and age-related diseases and can ultimately causes cell death. Detection of these oxidative modifications is essential to understand and discover new treatments against oxidative stress. We describe the design and the synthetic pathway of new BODIPY fluorescent probes functionalized with hydrazide function for protein carbonyl labeling to improve existing methodologies such as 2D-Oxi electrophoresis. Hydrazide BODIPY analogues show very good fluorescent properties such as NIR emission up to 633 nm and quantum yield up to 0.88. These new probes were validated for the detection and quantification of carbonylated proteins with 2D-Oxi electrophoresis using mouse muscle protein extracts, as well as both flow cytometry and microscopy using oxidant stressed C2C12 cells.

Dual-channel fluorescent sensors based on chitosan-coated Mn-doped ZnS micromaterials to detect ampicillin

The global threat of antibiotic resistance has increased the importance of the detection of antibiotics. Conventional methods to detect antibiotics are time-consuming and require expensive specialized equipment. Here, we present a simple and rapid biosensor for detecting ampicillin, a commonly used antibiotic. Our method is based on the fluorescent properties of chitosan-coated Mn-doped ZnS micromaterials combined with the β-lactamase enzyme. The biosensors exhibited the highest sensitivity in a linear working range of 13.1–72.2 pM with a limit of detection of 8.24 pM in deionized water. In addition, due to the biological specificity of β-lactamase, the proposed sensors have demonstrated high selectivity over penicillin, tetracycline, and glucose through the enhancing and quenching effects at wavelengths of 510 nm and 614 nm, respectively. These proposed sensors also showed promising results when tested in various matrices, including tap water, bottled water, and milk. Our work reports for the first time the cost-effective (Mn:ZnS)Chitosan micromaterial was used for ampicillin detection. The results will facilitate the monitoring of antibiotics in clinical and environmental contexts.

Synthesis and characterization of fluorescent and thermochromic bifunctional composites: Polydiacetylene/zinc oxide quantum dots

Composites of polydiacetylenes (PDA) and zinc oxide (ZnO) find diverse applications in thermochromic inks, colorimetric sensors, and anticounterfeiting, albeit often with complex preparation methods, single functionality, and high color-changing temperature ranges. This study presents environmentally friendly aqueous composites exhibiting dual thermochromic and fluorescent properties, achieved by integrating ZnO quantum dots (QDs) with particle sizes below 10 nm with PDA. By varying the concentration ratio of ZnO QDs to PDA, the effects on fluorescence and thermochromic properties were systematically explored. The interaction between ZnO QDs and PDA interfaces causes alterations to the energy states in the conjugated π-orbital array within PDA molecules. In contrast to pure PDA solutions, the composite materials not only exhibit thermochromism but also fluorescence. Demonstratively, the composite was applied as functional ink or paste for writing, film production, and inkjet printing, maintaining robust thermochromic sensitivity and fluorescence properties in the resulting specimens. This methodology imparts excellent multifunctionality to composite materials, enhancing and broadening their application potential.

Optical and fluorescent properties in Er, Yb:YAG double-line waveguide by femtosecond laser direct writing

This paper reports the double-line waveguides in Er,Yb:YAG prepared by femtosecond laser (fs-laser) writing at 1030 nm, 450 fs pulse and 100 kHz repetition rate. When light propagates at 632.8 nm along transverse electric (TE) and transverse magnetic (TM) polarization, efficient single-mode guidance is demonstrated in the double-line structures. The minimum transmission loss is as low as 0.98 dB/cm in waveguide with space of 18 μm. The structural modifications in damaged tracks and strain-affected regions were characterized by confocal micro-Raman spectroscopy, and the refractive index variations were analyzed. The corresponding fluorescence emissions of Er3+ and Yb3+ are investigated in the Er,Yb:YAG double-line structure.

Post-macrocyclization strategy to octaphenoxy-substituted zinc pyrazinoporphyrazine, its photochemical and electrochemical properties

An efficient post-macrocyclization strategy to new octaphenoxy-substituted zinc pyrazinoporphyrazine has been developed. This approach allows avoiding the template synthesis of the target compound from the phenoxy-substituted dinitrile, during which oligomerization and phenol release occur. The possibility of obtaining the initial octachloropyrazinoporphyrazine using template synthesis activated thermally and using microwave irradiation has been shown. Octaphenoxy-substituted zinc pyrazinoporphyrazine demonstrates short but intense triplet signals in triplet absorption spectrum and substantial singlet oxygen quantum yield (ΦΔ = 0.34). The fluorescent properties and fluorescence decay kinetics of target porphyrazines were studied. In contrast to the initial poorly soluble chlorinated complex, cyclic voltammetric measurements show both reduction and oxidation processes. Two waves of reduction and one wave of oxidation were observed. The electron-donating nature of phenoxy groups compared to chlorine groups is shown.