Search results for "Fluorescence"

Phospholipid-polyaspartamide micelles for pulmonary delivery of corticosteroids

2011

A novel drug delivery system for beclomethasone dipropionate (BDP) has been constructed through self-assembly of a pegylated phospholipid-polyaminoacid conjugate. This copolymer was obtained by chemical reaction of α,β-poly(N-2-hydroxyethyl)-DL-aspartamide (PHEA) with 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[amino(polyethyleneglycol)2000] (DSPE-PEG(2000)-NH(2)). Benefiting from the amphiphilic structure with the hydrophilic shell based on both PHEA and PEG and many hydrophobic stearoyl tails, PHEA-PEG(2000)-DSPE copolymer was able to self assemble into micelles in aqueous media above a concentration of 1.23 × 10(-7)M, determined by fluorescence studies. During the self-assembling …

Exposure to malondialdehyde induces an early redox unbalance preceding membrane toxicity in human erythrocytes.

2002

This work investigated the oxidative injury to human red blood cells (RBCs) by the exposure to exogenous malondialdehyde (MDA), in a physiological environment. When a 10% RBC suspension was incubated in autologous plasma, in the presence of 50 microM MDA, 30% of MDA entered into the cells. A time-course study showed that MDA caused early (30-120 min) and delayed (3-18 h) effects. MDA caused a fast depletion of reduced glutathione, and loss of the glucose-6-phosphate dehydrogenase activity, followed by a decrease of HbO2. Accumulation of methemoglobin, and formation of small amounts of hemichrome were later evident. Also, an HbO2-derived fluorescent product was measured in the membrane. The …

Oligomeric Sensor Kinase DcuS in the Membrane of Escherichia coli and in Proteoliposomes: Chemical Cross-linking and FRET Spectroscopy

2010

The DcuSR (dicarboxylate uptake sensor and regulator) system of Escherichia coli is a typical two-component system consisting of a membranous sensor kinase (DcuS) and a cytoplasmic response regulator (DcuR) (11, 26, 48). DcuS responds to C4-dicarboxylates like fumarate, malate, or succinate (19). In the presence of the C4-dicarboxlates, the expression of the genes of anaerobic fumarate respiration (dcuB, fumB, and frdABCD) and of aerobic C4-dicarboxylate uptake (dctA) is activated. DcuS is a histidine protein kinase composed of two transmembrane helices with an intermittent sensory PAS domain in the periplasm (PASP) that was also termed the PDC domain (for PhoQ/DcuS/DctB/CitA domain or fold…

Prevalence of Angelman syndrome and Prader-Willi syndrome in Estonian children: sister syndromes not equally represented.

2006

In 2000-2004, we performed a focused search for individuals with Angelman syndrome (AS) and Prader-Willi syndrome (PWS) aiming to establish the prevalence data for the individuals born between 1984 and 2004 in Estonia. All persons with probable AS or PWS (n = 184) were studied using the DNA methylation test. Individuals with abnormal methylation were all further tested by chromosomal and FISH analysis, and if necessary for uniparental disomy and UBE3A gene mutation. Nineteen cases with abnormal methylation test result were identified. Seven of them had AS, including six (85.7%) due to 15q11-13 deletion and one paternal UPD15. Twelve subjects had PWS: 4 (33%) 15q11-13 deletions, 6 (50%) mate…

Effect of ethanol on membrane fluidity of protoplasts fromSaccharomyces cerevisiae andKloeckera apiculata grown with or without ethanol, measured by …

1994

Direct measurements of membrane fluidity by fluorescence anisotropy of protoplasts fromKloeckera apiculata andSaccharomyces cerevisiae, a low and a high ethanol tolerant strain respectively, are presented. The comparison of the behaviour of the two strains grown with or without ethanol enabled us to demonstrate the existing relationship between ethanol tolerance and membrane fluidity.

An ethoxylated surfactant enhances the penetration of the sulfated laminarin through leaf cuticle and stomata, leading to increased induced resistanc…

2016

International audience; Some β-1,3-glucans and particularly sulfated laminarin (PS3) are known as resistance inducers (RIs) in grapevine against the downy mildew. However, their efficacy in vineyard is still often too low, which might be caused by a limited penetration through the leaf cuticle following spray application. We used (14) C-sucrose uptake experiments with grapevine leaves in order to select a surfactant as saccharide penetration enhancer. Our results showed that though sucrose foliar uptake was low, it was strongly enhanced by Dehscofix CO125 (DE), a highly ethoxylated surfactant. Fluorescent saccharides were then produced and laser scanning microscopy was used to analyze their…

Spectroscopic study of the aluminium/lumogallion system in the presence of non-ionic surfactants

1987

Abstract The effects of different non-ionic ethylene oxide condensate surfactants on the fluorescence and the molecular absorption of the aluminium/lumogallion system are reported. Ethylene oxide condensates with fatty alcohols give higher micellar enhancement factors than tert-octylphenols or nonylphenols; ethylene oxide/propylene oxide copolymers provide only a 50% increase in the fluorescence of the complex. The aluminium/lumogallion seems to form mixed micelles with the fatty alcohol condensates; the strong complex/micelle interaction provides increased absorbance of the complex at 500 nm and higher fluorescence enhancement, allowing the detection of 0.11 μg l −1 aluminium.

Light-induced trans-cis isomerization of terpyridine functionalized POSS nanostructures self-assembled in presence of Eu3+ ions

Fluorescent interaction Eu-IL: when the anion plays a role

2020

An analytical method for monitoring micro-traces of landfill leachate in groundwater using fluorescence excitation–emission matrix spectroscopy

2016

In this study, we use three-dimensional excitation-emission matrix (EEM) fluorescence spectroscopy for the identification of contamination of natural water bodies by landfill leachate. In particular, EEM was applied to provide information about the presence and quantities of leachate in ground waters. A good linear relationship was found between the fluorescence intensity emission of groundwater spiked with landfill leachate and the volumes of the latter, suggesting that there was no intrinsic fluorescence in the concentration range of 0-1000 μL L-1. The obtained values of the LOD (10 μL L-1; TOC = 34 μg L-1) and LOQ (34 μL L-1; TOC = 114 μg L-1) allow us to detect the presence and the amou…