Analysis Of Fluorescence Emission Research Articles

Lipid droplet dynamics are essential for the development of the malaria parasite Plasmodium falciparum.

Lipid droplets (LDs) are organelles that are central to lipid and energy homeostasis across all eukaryotes. In the malaria-causing parasite Plasmodium falciparum the roles of LDs in lipid acquisition from its host cells and their metabolism are poorly understood, despite the high demand for lipids in parasite membrane synthesis. We systematically characterised LD size, composition and dynamics across the disease-causing blood infection. Applying split fluorescence emission analysis and three-dimensional (3D) focused ion beam-scanning electron microscopy (FIB-SEM), we observed a decrease in LD size in late schizont stages. LD contraction likely signifies a switch from lipid accumulation to lipid utilisation in preparation for parasite egress from host red blood cells. We demonstrate connections between LDs and several parasite organelles, pointing to potential functional interactions. Chemical inhibition of triacylglyerol (TAG) synthesis or breakdown revealed essential LD functions for schizogony and in counteracting lipid toxicity. The dynamics of lipid synthesis, storage and utilisation in P. falciparum LDs might provide a target for new anti-malarial intervention strategies.

2-(((4-(Trifluoromethyl)quinolin-6-yl)amino)methyl)phenols: Synthesis, optical properties, thermal, and electrochemical behavior

This paper describes the synthesis, photophysical properties, and thermal and redox behavior of a novel series of nine selected 2-(((2-substituted-4-(trifluoromethyl)quinolin-6-yl)amino)methyl)phenols (4). These phenols contain 2-Me, 2-aryl, or 2-(2-furyl)-quinolines and 5-OMe, 4-Br or 4-NO2 substituted amino methylphenol cores assembled in the scaffolds of 4. Optimized yields of 51–98 % were obtained when the reactions of the respective imines 3 were conducted with sodium borohydride in ethanol at 80 °C for 30 min. The structural characterization of compounds 4 was performed by multinuclear NMR, FTIR, and HRMS techniques. Thermogravimetric analysis experiments indicated that the majority of the compounds obtained exhibited high thermal stability at temperatures over 200 °C. The UV–Vis steady-state and time-resolved fluorescence emission, TD-DFT calculations, and redox analyses were used to determine the photophysical and electrochemical properties of the studied derivatives, revealing a correlation between the electronic effects of the substituents attached to the quinoline and phenol cores and the evaluated parameters.

Comparative Analysis of Fluorescence Emission in Myricetin, Kaempferol, and Quercetin Powders and Solutions.

Myricetin is a flavonol with high antioxidant properties. In this research, the fluorescence emission of myricetin powder and its solutions in different solvents were measured and analyzed by comparing with the results of calculations. Comparison of the calculated and measured characteristic wavelengths allowed the identification of all the spectral features in the fluorescence spectra of myricetin powder and solutions with different concentrations. The computation was based on modeling the process of the excited state intermolecular proton transfer, which predicts the formation of tautomeric forms of the flavonol molecule. Characteristic emission wavelengths were obtained using TDDFT/M06-2X/6-31++G(d,p). To understand the influence of the hydroxyl groups in the B-ring of the flavonol molecule on the emission spectrum, we also compared the fluorescence spectra of myricetin with those of kaempferol and quercetin. Moreover, based on the analysis of the changes in the shape of the FL spectra with the concentration of the solution, a criterion for the complete dissolution of the flavonol powders was established, which is important for bioavailability of flavonoids.

Photoluminescence Properties of Polythiophene/Tin Oxide (PTh/SnO2) Polymer Nanocomposites

In the present work, we have synthesized, polythiophene/tin oxide (PTh/SnO2) polymer nanocomposites through an in-situ chemical polymerization of thiophene monomers using anhydrous FeCl3 as an oxidant. The structural, thermal and optical characterization of PTh/SnO2 nanocomposites were investigated using X-ray diffraction, field emission scanning electron microscopy, thermogravimetric analyzer and fluorescence emission spectroscopy. XRD spectra show the formation of pure polythiophene and incorporation of SnO2 nanofiller into the polythiophene matrix. FESEM images depict the formation of irregular rod and chain like structures with incorporation of SnO2 are noticed. TGA results reveal that the thermal stability of polymer nanocomposites is higher than that of pure polythiophene due to the strong interaction between nanofiller and polymer matrix. Fluorescence emission spectra show the emission intensity of polymer nanocomposites decreases as the concentration of SnO2 nanofiller increases due to the variation of rate of electron-hole recombination and conjugation length of polymer chain. Our results of fluorescence emission analyses suggest the PTh/SnO2 polymer nanocomposites could be a potential material for photonic devices.

Laser-induced X-ray fluorescence and electron-based X-ray emission analysis of multi-layer material

Laser-induced X-ray fluorescence and electron-based X-ray emission analysis of multi-layer material

Synthesis and characterization of surface-modified ultrafine titanium dioxide nanoparticles with an antioxidant functionalized biopolymer as a therapeutic agent: Anticancer and antimicrobial evaluation

Surface modified biodegradable protein-based nanoparticles have great potential in pharmaceutical applications. In the present study, we discuss the surface engineering of titanium dioxide nanoparticles (TiO2 NPs) with alpha-lipoic acid (ALA) functionalized bovine serum albumin (BSA) conjugate as a biocompatible therapeutic system. Sol-gel method is used to synthesize TiO2 NPs, which is characterized using ultraviolet (UV)/visible, Fourier transform infrared (FT-IR), X-ray diffraction analysis (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). BSA was functionalized with antioxidant ALA by Steglich esterification, and TiO2 NPs were loaded into this synthesized BSA-ALA conjugate. The finally developed product was studied using various characterization methods like UV-Visible, FT-IR, XRD, SEM-EDX, TEM, TG-DTG, DSC and fluorescence emission analysis. In vitro cytotoxicity of this system was examined by applying the trypan blue exclusion method, and antimicrobial analysis was implemented by well diffusion method against antibiotic-resistant bacterial and fungal strains.

A comprehensive understanding of multiple emissive states in S and N doped carbon dots and the highly selective detection of Cr(VI)

Although exceptional progress has been observed in enhancing the quantum yield and tuning the emission of carbon dots (CDs) in the recent past, the origin of photoluminescence is hazy due to the structural complexity. In this work, we synthesised luminescent S and N co-doped CDs, termed as SNCDs, via hydrothermal carbonisation of glutathione. We performed detailed photophysical studies, including fluorescence excitation, emission and time resolved analysis to understand its pH dependence luminescence in the SNCDs. Based on the results, a comprehensive energy level diagram for the SNCDs has been proposed, explaining the origin of multiple emissive states in SNCDs, contributed by core, surface, and edge states. The results are useful in tuning the emission properties of CDs and related materials for various optical applications. We demonstrate a highly selective fluorescence detection strategy for the Cr(VI) using the SNCDs as a fluorophore.

Higher-order photon antibunching of phase-variable squeezed coherent state

<sec>Squeezed state has important applications in quantum communication, quantum computing, and precision measurement. It has been used to improve the sensitivity and measurement accuracy of gravitational wave detectors. Currently, squeezed state can be prepared by optical parametric oscillators, four-wave mixing, and atom–optomechanical coupling. As a typical non-classical light, the photon statistics of squeezed state usually shows obvious bunching effect, but it can also present photon antibunching effect through interference or photon subtraction operation. More importantly, squeezed coherent state is prepared by performing displacement operation on the squeezed state. In the case of certain displacement and squeezing operations, squeezed coherent state with obvious antibunching effect can be produced. The squeezed coherent state with photon antibunching effect can be employed to achieve super-resolution imaging beyond the diffraction limit, and the state exhibits good particle features which can suppress the multiphoton emission. Then it has become a focus for studying the antibunching effect and quantum statistical properties of squeezed coherent state at a single-photon level.</sec><sec>The photon antibunching effect can be characterized by the second-order photon correlation <i>g</i><sup>(2)</sup>(τ), which is introduced by Glauber to determine the non-classical properties of the light field. Namely, the second-order photon correlation <i>g</i><sup>(2)</sup> can be used as a metric to distinguish different lights. Hanbury Brown-Twiss (HBT) scheme is used to measure the second-order photon correlation experimentally. However, the second-order photon correlation <i>g</i><sup>(2)</sup> can reflect only the variance of the photon-number statistical distribution. In order to obtain more information about the photon statistical distribution and non-classical features, it is necessary to measure higher-order photon correlations. Then the higher-order photon correlations for different light fields are studied by extending the traditional HBT scheme and combining with multiplex single-photon detection technology. This method can be applied to ghost imaging, characterization of single-photon detectors, research of exciton dynamics, and analysis of NV center fluorescence emission. However, the research on photon statistics of the squeezed state focuses mainly on the second-order photon correlation and the effect of displacement amplitude on the statistical properties. The effect of squeezed phase on photon antibunching and higher-order photon correlation of squeezed coherent states, with background noise and detection efficiency taken into consideration, have not been investigated.</sec><sec>In this paper, we study high-order photon correlations and antibunching effect of phase-variable squeezed coherent state based on an extended HBT scheme. The photon statistics of the squeezed coherent state manifests prominent antibunching effect by adjusting the squeezing parameter r, displacement amplitude <i>α</i> and squeezing phase <i>θ</i>. The antibunching effect of the state can be obtained in a wide range of <i>α</i>-<i>r</i> parameter space when squeezing phase <i>θ</i>∈[0,π/2]. In an ideal case, the minimum antibunching values of the squeezed coherent state are <i>g</i><sup>(2)</sup> = 4.006 × 10<sup>–4</sup>, <i>g</i><sup>(3)</sup> = 1.3594 × 10<sup>–4</sup> and <i>g</i><sup>(4)</sup> = 6.6352 × 10<sup>–5</sup>. When the detection efficiency <i>η</i> = 0.1 and background noise <i>γ</i> = 10<sup>–6</sup>, the strong antibunching effect can still be observed, specifically, <i>g</i><sup>(2)</sup> = 0.1740, <i>g</i><sup>(3)</sup> = 0.0432, <i>g</i><sup>(4)</sup> = 0.0149. The results indicate that the antibunching effect of higher-order photon correlation has strong robustness against the experimental environment. In addition, the antibunching effect of the phase-variable squeezed coherent state is studied as a function of the measured mean photon number <<i>n</i>> and the squeezing degree S. When the measured mean photon number is much less than 1 and the squeezing parameter is less than 10<sup>–4</sup>, a prominent photon anti-bunching effect of <i>g</i><sup>(<i>n</i>)</sup> <inline-formula><tex-math id="Z-20220921173504">\begin{document}$\ll $\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="19-20220574_Z-20220921173504.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="19-20220574_Z-20220921173504.png"/></alternatives></inline-formula> 0.5 can still be obtained. The results show that the control of the squeezing phase <i>θ</i> can be used to prepare the squeezed coherent state with obvious antibunching effect, which has potentially important applications in quantum metrology and secure communication.</sec>

Investigating ESIPT and donor-acceptor substituent effects on the photophysical and electrochemical properties of fluorescent 3,5-diaryl-substituted 1-phenyl-2-pyrazolines

This paper describes the synthesis, structural study, and evaluation of electrochemical and photophysical properties by UV–Vis absorption and fluorescence emission analysis (solution and solid-state) of a series of eight 3,5-aryl-substituted 1-phenyl-2-pyrazolines (5), where 3-aryl = 2-OH-C6H4 (5a-g) or Ph (5h), and 5-aryl = Ph (a, h), 1-naphthyl (b), 4-Br-C6H4 (c), 4-F-C6H4 (d), 4-OCH3-C6H4(e), 4-NO2-C6H4 (f), 4-(N(CH3)2)-C6H4(g). The UV–Vis absorption properties of 2-pyrazolines were evaluated in DCM, MeCN, AcOEt, EtOH, and DMSO as the solvent and showed a fluorescence shift for the polar aprotic solvents. The steady-state fluorescence emission exhibited a band in the blue region when excited at the least energetic transition of each compound, although the excited-state intramolecular proton (ESIPT) effect was not detected. In the solid state, compounds presented similar behavior regarding absorption and emission properties compared to the solution assays. With the electrochemical analyses performed for the synthesized 2-pyrazolines, it was possible to conclude that the redox potentials were influenced by the electronic and steric effects of the substituents on the aryl rings and, according to the electronic nature of the substituents, which electron-donating groups were favored. Finally, the TD-DFT analyses revealed that all compounds had delocalized electron density throughout the 2-pyrazolines unit and were not influenced by the substituent bonded at C-5. Nonetheless, LUMO orbital analysis showed that only derivatives 5b and 5f have this localized density over the substituents.

Highly fluorescent carbon dots from wheat bran as a novel drug delivery system for bacterial inhibition.

In this study, we prepared carbon dots (CDs) from wheat bran via hydrothermal treatment at 180°C for 3 h. The prepared CDs showed blue-green fluorescence under UV light. The fluorescence emission study of the CDs revealed that they showed maximum fluorescence emission at 500 nm. The prepared CDs showed a high quantum yield of 33.23%. Solvent-dependent fluorescence emission analysis of the CDs was performed to study the variation in fluorescence emission characteristics with solvent polarity. The prepared CDs were conjugated with amoxicillin (AMX) to explore its potential for use as a drug delivery agent for AMX. The drug release profile of the CD-AMX conjugates was analyzed at different pH (5.0, 6.8 and 7.2) to study drug release kinetics. CD-AMX conjugates showed notable bacterial inhibition against Gram-positive (S. aureus) and Gram-negative (E. coli) strains with minimal cytotoxic effects, indicating its potential as a promising antibacterial drug delivery system.

Self-assembled hydrophobic Ala-Aib peptide encapsulating curcumin: a convenient system for water insoluble drugs.

The exploitation of self-assembled systems to improve the solubility of drugs is getting more and more attention. Among the different types of self-assembled biomaterials, peptides and in particular peptides containing non-coded amino acids (NCAPs) are promising because their use opens the door to more stable materials inducing increased stability to proteolysis. New classes of NCAP, Ac-Ala-X-Ala-Aib-AlaCONH2 (X = alpha-aminoisobutyric acid (Aib) or X = cyclopentane amino acid (Ac5c)) have been prepared and the correlation between the different secondary peptide structure and solvent (i.e. CD3CN, CD3OH, H2O/D2O) verified by NMR. Furthermore, the formation of a nanocolloidal system in water was deeply studied by DLS and the morphology of the obtained spherical aggregates with nanometric dimensions was assessed by TEM. Aib containing pentapeptide was selected for greater ease of synthesis. Its ability to encapsulate curcumin, as a model insoluble drug molecule, was investigated using fluorescence emission and confocal microscopy analyses. Two different approaches were used to study the interaction between curcumin and peptide aggregates. In the first approach peptide aggregates were formed in the presence of curcumin, while in the second approach curcumin was added to the already formed peptide aggregates. We succeeded in our challenge by using the second approach and 53.8% of added curcumin had been encapsulated.

Impact of forest management on threatened epiphytic macrolichens: evidence from a Mediterranean mixed oak forest (Italy)

Abstract: Forest management practices may heavily affect epiphytic cryptogams. This study was conceived in March 2016, as soon as we were informed about an authorized logging for timber within a Mediterranean mixed oak forest in Tuscany (central Italy), which threatened a large population of the forest macrolichen Lobaria pulmonaria (L.) Hoffm., composed of hundreds of fertile thalli. Lobaria pulmonaria is often used as an ecological indicator of high quality habitats hosting rare lichens, and in general, cryptogams worthy of conservation. The species has suffered a general decline throughout Europe as a consequence of air pollution and intensive forest management, and currently it is red-listed in several countries, where it is considered also as a “flag species”. We estimated that 40% of the lichen biomass (8.5-12.3 kg ha-1) has been lost due to logging operations (in the core area, up to 1.8 kg every 100 m2), in particular large and fertile thalli. One year after the conclusion of logging operations, the analysis of chlorophyll fluorescence emission (indicator of the photosynthetic performance of the lichen photobionts), revealed a significant reduction of the vitality of the thalli on retained-isolated trees. The article provides issues for conservation in Mediterranean oak forests and outlines the outmost importance of ensuring the safeguard of forest ecosystems hosting fertile populations of this model species, especially in the case of unprotected forests.

Acanthopanacis Cortex extract: A novel photosensitizer for head and neck squamous cell carcinoma therapy.

The aim of this study was to develop a novel photosensitizer from traditional plant extracts and to investigate the photodynamic therapy (PDT) effect and mechanism of action of the novel photosensitizer on KB and Hep-2 cells. Fluorescence emission, cell viability, and intracellular distribution of candidates were analyzed to screen potential photosensitizers from traditional plant extracts. Cellular reactive oxygen species (ROS) quantification, Annexin V-FITC/PI staining, and western blotting were performed to explore the mechanism of cell death in KB and Hep-2 cells. Of 289 traditional plant extracts, 13 plant extracts with strong fluorescence were initially screened by fluorescence emission analysis. The cell viability assay and intracellular distribution of candidates showed that Acanthopanacis Cortex (AC) extract is a potential photosensitizer. Under optimal PDT conditions, high levels of ROS were produced in KB and Hep-2 cells, followed by cell death. However, there was no significant damage to HaCaT cells. Moreover, apoptosis induced by AC extract with 625 nm irradiation (IR) down-regulated the expression of Bcl-2 protein and up-regulated the expression of Bax protein, as well as that of cleaved PARP-1 protein in both KB and Hep-2 cells. The fluorescence intensity of AC extract at 420 nm is similar to that of the commercial Hematoporphyrin (HP). AC extract with 625 nm IR could enhance the PDT effect, induce ROS generation, and trigger apoptotic pathways in KB and Hep-2 cells. Therefore, we suggest that AC is a potential novel photosensitizer for PDT in head and neck squamous cell carcinoma.

Changes in soil organic matter and soil humic substances following the afforestation of former agricultural lands in the boreal-nemoral ecotone (Latvia)

Abandonment of agricultural land is a widespread process in Northern Europe, which is associated with changes in content and distribution of organic matter in soil, including C stocks. There is insufficient information on changes in soil organic matter properties during afforestation of these lands. The aim of the study was to determine and describe the influence of afforestation on organic carbon (CORG) content and properties of soil organic matter (SOM) in mineral topsoil in the boreo-nemoral ecotone in Latvia. We studied soils in 4 model territories that represented abandoned farmlands and territories where mixed or coniferous forests were established at different times on former agricultural lands. Soil samples from mineral topsoil (genetic A or AE horizons) were obtained during the summer period in two model territories (11 sampling sites) with loamy texture soil, and two model territories with higher sand content of soil (9 sampling sites). The soil samples were analysed for organic carbon (CORG) and total nitrogen (NTOT) content. Soil alkali (NaOH) extracts were used to determine properties of soil organic matter – alkali extractable carbon (CHS) content, composition and humification index (HIX) of soil humic substances (HS) and spectroscopic (UV–Vis, fluorescence emission spectra, FTIR) properties of the soil humic acid fraction (HA). CORG content gradually increased with forest land age. Gradual decrease in the humic acid (HA) to fulvic acid (FA) ratio (CHA/CFA) after land-use change indicated that SOM was transported to mineral topsoil mainly through leaching of the soluble FA fraction. FTIR spectra revealed that the HA fraction from all studied soils had relatively similar chemical structure and that SOM in mineral topsoil was degraded to relatively similar compounds. However, HAs extracted from forest soils had higher abundance of –OH groups, more aromatic CC structures, and relatively lower abundance of NH groups in amides. UV–Vis and fluorescence emission spectroscopic analysis of HA fraction along with PCA analysis showed that soil properties also may have affected chemical properties of soil organic matter during the afforestation. Molecular weight of the HA fraction gradually increased with age of the forest land in sandy soils while there were no significant changes in sandy loam soils. Fluorescence emission analysis also showed that HAs extracted from EAh horizons in Podzol and Anthrosol soils in old forest lands had the highest aromaticity.The results suggest that sandy soils have the most dynamic changes in SOM properties after afforestation. Therefore, further studies should focus on whether and how these changes affect SOM fate in soils, physical stabilisation with mineral soil and SOM leaching into subsoil.

Evaluation of Dissolved Organic Carbon Using Synchronized Fluorescence Emission Spectra and Unsupervised Method of Principal Component Analysis (PCA) and Independent Component Analysis (ICA)

Dissolved organic matter (DOM) can be originated from autochthonous or allochthonous sources, where allochthonous DOM can be from pedogenic sources (humic substances—HSs) or anthropogenicsources (wastewater). The analysis of fluorescence emission, excitation, synchronous or excitation-emission matrix (EEM) have been used to identify the main source or probable contribution of dissolved compounds, such as humic acids (HA), fulvic acids (FA) and dissolved organic carbon (DOC) from sewage, but does not quantify. Fluorescence emission is a powerful technique to detect and qualify organic dissolved compounds but fails in quantitative aspects. In this work, we propose an in situ method for direct determination of DOC using synchronous fluorescence spectra with independent component analysis (ICA). Well known standard solutions were used for method development and validation. In this work, we show that it is possible to predict the number of independent contributions using an unsupervised method based on iterative Principal Component Analysis and Independent Component Analysis (PCA-ICA) approach over combined matrix results. Within these results it’s also possible to see that with a very small amount of independent components it is possible to describe environmental samples of HA, FA and primary productivity (PP).

High-throughput identification and quantification of Haemonchus contortus in fecal samples

Haemonchus contortus are gastrointestinal nematodes of the family Trichostrongylidae that naturally infect small ruminants while grazing, posing a risk to both animal health and farm profitability. Current diagnostics depend on exacting lab techniques, including manual egg counts and larval differentiation, all of which require time, effort, and specialized technicians. The goal of this study was to facilitate and accelerate the identification and quantification of H. contortus in fecal samples through the use of fluorescein-isothiocyanate peanut-agglutinin staining in order to allow automated detection using a 96-well microplate reader. Next, the model was to be validated using samples containing unknown quantities of eggs. Automated analysis of fluorescence emission of known quantities of H. contortus eggs confirmed an almost perfect linear correlation (r = 0.9984, p < 0.0001), indicating that this new approach can satisfactorily be used to quantify H. contortus eggs on a comparative fluorescence scale. As validation, clinical samples containing an unknown quantity of H. contortus eggs were then analyzed by comparing two methods: either Wisconsin Sugar Flotation (WSF) and McMaster counting followed by manual fluorescence microscopy, or WSF coupled with automated microplate reading. Pearson analysis revealed highly significant correlation between manual and automated methods (r = 0.9999, p < 0.0001), while Bland-Altman plots demonstrated excellent agreement between the two (bias = −0.817 ± 9.94 with 95% limits of agreement from −20.31 to 18.67). Overall, these results demonstrate that high-throughput screening fluorescence detection and quantification of H. contortus eggs is both accurate and rapid.

Micro-fluorescence lifetime and spectral imaging of ytterbium doped laser materials.

We present the application of a confocal fluorescence microscope to the analysis of Yb-doped solid-state laser materials, with examples of Yb-doped crystals, photonic crystal fibers and fiber preforms made with different manufacturing processes. Beside the fluorescence lifetime image itself, a microscopic spectral fluorescence emission analysis is presented and spatially resolved emission cross sections are obtained. Doping concentration and its distributions and other laser optical parameters are measured, which help to analyze manufacturing steps. Further properties like photodarkening and saturation are addressed.

Synthesis, spectroscopy, electrochemistry and DNA interactive studies of meso-tetra(1-naphthyl)porphyrin and its metal complexes

A simple methodology to design metal-free porphyrin (meso-tetra-(1-naphthyl)porphyrin) and their corresponding transition metal complexes (Zn(II), Cu(II), Ni(II), Co(III) and Mn(III)) is described. These porphyrins were fully characterized by elemental analysis, HRMS-ESI, UV–vis absorption, steady state fluorescence emission, theoretical calculations and electrochemical analysis. Photo-stability and singlet oxygen generation species were also evaluated. Spectroscopic studies and molecular docking calculations evinced the ability of each porphyrin derivatives to establish interactions with calf-thymus DNA (ct-DNA).

Synthesis and luminescence properties of CdSe:Eu NPs and their surface polymerization of poly(MMA-co-MQ)

CdSe:Eu nanoparticles (NPs) were synthesized using an oil phase method and the substitution of Cd2+ with Eu3+ was confirmed by XRD, TEM, UV-Vis absorption and fluorescence emission analyses. The CdSe:Eu NPs are monodispersed and uniform spherical particles with a diameter of 3.2 nm, bigger than the pure CdSe NPs (2.3 nm), but with a similar cubic structure as CdSe NPs. Compared with those of pure CdSe NPs, both emission spectrum and absorption spectrum of CdSe:Eu NPs are red-shifted. The CdSe:Eu NPs are incorporated into poly(MMA-co-MQ) to afford poly(MMA-co-MQ)-CdSe:Eu NPs with the cubic structure and particle size (∼3–4 nm) similar to those of CdSe:Eu NPs. The TEM imaging suggests that the CdSe:Eu NPs are uniformly dispersed in poly(MMA-co-MQ) without any obvious aggregation. The fluorescent emission peak and absorption peak of poly(MMA-co-MQ)-CdSe:Eu NPs are between those of CdSe:Eu NPs and poly(MMA-co-MQ), possibly due to the energy transfer caused by the interactions of Cd or Eu atoms on the surfaces of CdSe:Eu NPs with the N and O atoms of poly(MMA-co-MQ). These CdSe:Eu and poly(MMA-co-MQ)-CdSe:Eu NPs with tunable photoluminescence properties can be potentially used for the fabrication of optical and optoelectronic devices.

Characterization of Amyloid-β Plaques and Autofluorescent Lipofuscin Aggregates in Alzheimer's Disease Brain: A Confocal Microscopy Approach.

The study of brain pathology by fluorescence microscopy finds in the autofluorescence of the tissue an additional difficulty for the recognition of markers of interest. In particular, in the immunofluorescence study of brains from Alzheimer's disease (AD) patients, several approaches have been attempted to eliminate or mask the presence of autofluorescent aggregates. In the present work, we propose a method to characterize by fluorescent microscopy senile plaques discriminating them from autofluorescent aggregates, such as lipofuscin granules.This work describes four protocols carried out in human brain tissue of patients with AD, covering adequate tissue preparation, immunofluorescence acquisition, and data analysis: 1. Tissues processing of frozen samples for optimal epitope conservation. 2. Analysis of the fluorescence emission spectrum of the tissue by performing a confocal microscopy λ-scan. 3. Analysis of fluorescence emission of both intact and formic acid-treated tissues in four channels corresponding to the emission in blue, green, near red, and far-red regions. 4. Analysis a specific immunostaining of amyloid beta in senile plaques, using fluorescent-labeled antibodies by using specific emission channels to avoid detection of tissue autofluorescence.