Quenching of long lifetime emitting fluorophores with paramagnetic molecules

International audienceIn this work, we have studied quenching of the fluorescence of two well-known oxygen probes, 1-pyrene butyric acid (PBA) and tris(2,2'-bipyridine)ruthenium ([Ru(bpy)(3)](2+)) by reactive oxygen species (superoxide anion, nitric oxide derivative, hydrogen peroxide) and by the O(2) molecule. Both, time-resolved and steady state fluorescence measurements were performed in solution (ethanol, dimethyl sufoxide, water) and in micelles of Sodium Dodecyl Sulfate that serve as a model for membrane-containing biological structures. We have found that only the free radicals and O(2) can actively quench for the two probes, but not the diamagnetic H(2)O(2). Our data correspond to the classical Stern-Volmer equation. H(2)O(2) has an effect only at high molar concentrations (>0.1 M). In contrast, effective concentrations of free radicals and O(2) that lead to quenching are in millimolar range. In conclusion, our methods allows for detecting global ROS that are small free radicals without interference from the reactive hydroxyl radical. Our data suggest that the method can be used for the quantification of ROS in individual living cells based on the measurement of fluorescence lifetime of those probe

A novel fluorescent nano-scale sensor for detection of trace amounts of Ca (II) ions

kacmaz, sibel/0000-0003-3642-4940; Ertekin, Kadriye/0000-0001-9819-3610WOS: 000331667900044A photo-induced electron transfer (PET) based sensing approach for the direct determination of trace amounts of calcium ions is presented. The Ca2+ selective fluoroionophore Bis, 2,2'-{1,2 phenylenebis [nitrilomethylylidene]} diphenol (DMK) was encapsulated in polymeric ethyl cellulose. The sensing membranes were fabricated in form of nanofibers, exploiting the. prepared polymer. When embedded in nanomaterials, the DMK dye yielded strong absorbance, large Stoke's shift, high fluorescence quantum yield, and excellent short and long-term photostability. The sensing ability of the nanofibers was tested by steady state and time resolved fluorescence spectroscopy. To our knowledge, this is the first attempt using the DMK-doped electrospun nanofibrous materials for calcium sensing. The offered nanosensor displays a sensitive response with a detection limit of 0.016 nM for Ca2+ ions over a wide concentration range, 1.0 x 10(-10)-1.0 x 10(-4) M, and exhibits high selectivity over Mg2+ and other cations. Accuracy of the sensing system was proven by recovery tests. (C) 2013 Elsevier B.V. All rights reserved.Scientific Research Funds of Dokuz Eylul UniversityDokuz Eylul University [2012.KB.FEN.049, 2012.KB.FEN.031]Funding this research was provided by the Scientific Research Funds of Dokuz Eylul University 2012.KB.FEN.049 and 2012.KB.FEN.031. We also thank to the Scientific and Technological Research Council of Turkey (TUBITAK)

Manipulation of pH induced sensitivity of a fluorescent probe in presence of silver nanoparticles

Hokelek, Tuncer/0000-0002-8602-4382; kacmaz, sibel/0000-0003-3642-4940; hizliates, cevher gundogdu/0000-0003-4980-2525; Ergun, Yavuz/0000-0003-2141-7975; Ertekin, Kadriye/0000-0001-9819-3610WOS: 000363353300035In this study, pH induced spectral response of the newly synthesized carbazole derivative (9-butyl-bis-3-(4-(dimethylamino) phenyl) allylidene)-9H-carbazole-3,6-diamine) has been declared. We utilized silver nanoparticles (AgNPs) along with ionic liquid as additives for manipulation of the spectral response. Plasticized ethyl cellulose (EC) was used as matrix material. Fibers and porous films were produced by electrospinning technique. The emission intensity at 631 nm has been followed as the analytical signal. Utilization of silver nanoparticles in electrospun polymeric fibers for pH sensing purposes resulted with many advantages such as tuned sensitivity, linear calibration plot for larger pH ranges, increased surface area and enhancement in all sensor dynamics. Additionally, we performed manipulation of the pKa within the same matrix exploiting the silver NPs. Characteristics of the pH induced response for the offered composition was superior with respect to the previously reported ones. When stored at the ambient air of the laboratory there was no significant drift in the signal intensity after 16 months. Our sensitivity and stability tests are still in progress. (C) 2015 Elsevier B.V. All rights reserved.Scientific Research Funds of Dokuz Eylul UniversityDokuz Eylul University [2012.KB.FEN.049]Funding this research was provided by Scientific Research Funds of Dokuz Eylul University (Project number of 2012.KB.FEN.049). We also thank to the Scientific and Technological Research Council of Turkey (TUBITAK). Also we would like specially thank to members of Center for Fabrication and Applications of Electronic Materials

Synthesis, structural characterization, oxygen sensitivity, and antimicrobial activity of ruthenium(II) carbonyl complexes with thiosemicarbazones

WOS: 000342306700003Ru(II) carbonyl complexes were prepared by reacting [Ru(H)(Cl)(CO)(PPh3)(3)] with the respective thiosemicarbazone ligands and the complexes were characterized by UV-vis, FT-IR, and H-1 and P-31 NMR spectroscopy. Oxygen sensitivities and antimicrobial activities of the complexes were determined. [Ru(CO)(PPh3)(2)(eta(3)-O, N-3, S-TSC1)] (1), [Ru(Cl)(CO)(PPh3)(2)(eta(2)-N-3, S-TSC2)] (2), and [Ru(Cl)(CO) (PPh3)2(eta(2)-N-3,S-TSC3)] (3) have been prepared by reacting [Ru(H)(Cl)(CO)(PPh3)(3)] with the respective thiosemicarbazones TSC1 (2-hydroxy-3-methoxybenzaldehyde thiosemicarbazone), TSC2 (3-hydroxybenzaldehyde thiosemicarbazone), and TSC3 (3,4-dihydroxybenzaldehyde thiosemicarbazone) in a 1 : 1 M ratio in toluene and all of the complexes have been characterized by UV-vis, FT-IR, and H-1 and P-31 NMR spectroscopy. The spectroscopic studies showed that TSC1 is coordinated to the central metal as a tridendate ligand coordinating via the azomethine nitrogen (C=N), phenolic oxygen, and sulfur to ruthenium in 1, whereas TSC2 and TSC3 are coordinated to ruthenium as a bidentate ligand through azomethine nitrogen (C=N) and sulfur in 2 and 3. Oxygen sensitivities of 1-3 and [Ru(Cl)(CO)(PPh3)(2)(eta(2)-N-3, S-TSC4)] (4), and antimicrobial activities of 1-3 have been determined.Dokuz Eylul University Rectorship, Scientific Research Project Coordination CenterDokuz Eylul University [2011.KB. FEN.047, 2012.KB. FEN.047]This study was supported by project number 2011.KB. FEN.047 and 2012.KB. FEN.047 from Dokuz Eylul University Rectorship, Scientific Research Project Coordination Center. We also thank the Graduate School of Natural and Applied Sciences, Dokuz Eylul University, EBILTEM, Ege University for NMR analysis, and TUBITAK, for elemental analysis

Determination of Hg(II) at sub-nanomolar levels: A comparative study with nanofibrous materials and continuous thin films

Emission based response of highly luminescent carbozole derivative, 2(9-methyl-9H-carbazol-3-yl)-5-(pyridin-4-yl)-1,3,4-oxadiazole (ODC-3), to Hg(II) ions was investigated. The dye was encapsulated in ionic liquid doped ethyl cellulose (EC) matrix in form of nanofibrous materials and continuous thin films. The nanofibers were fabricated by electrospinning technique. The ratiometric response to Hg(II) ions was monitored at 418 nm and 505 nm. The quenching behavior follows Stern-Volmer quenching kinetics. The ODC-3 dye can be used for quantitative determination of Hg(II) in the concentration range of 1.0 x 10(-11)-1.0 x 10(-3) M. With respect to continuous thin films, the electrospun nanofibers offered enhanced sensitivity, lower LOD values and shorter response times in optical chemical sensing of Hg(II). (C) 2013 Elsevier B.V. All rights reserved

International study on nurses' views and experiences of compassion

Compassion is considered the cornerstone of nursing practice. However, the recent failures in delivering high-quality compassionate nursing care in the UK's National Health Service have brought the topic of compassion to the attention of the public, service providers, policy makers and academics

Exploring nurses' meaning and experiences of compassion: an international online survey involving 15 countries

Purpose: In recent years, there has been much focus on compassion in nursing care, and concern has been raised in a number of reports and media stories regarding decreased compassion. The aim of this study was to explore similarities and differences in the understanding and demonstration of compassion in nursing practice across 15 countries. Design: A total of 1,323 nurses from 15 countries responded to questions in relation to compassion, via an international online survey. Results: The data revealed the impact of sociopolitical influences on perceptions of compassion, and the conscious and intentional nature of compassion. Discussion and Conclusion: The study demonstrated shared understandings of the importance of compassion as well as some common perceptions of the attributes of compassionate care. The differences reported were not as significant as had been expected. Implications for Practice: Further research is needed to explore the country and culture differences in the enactment of compassion