1,721,006 research outputs found
Isoquinoline-based Eu(III) luminescent probes for citrate sensing in complex matrix. International Symposia on Thermodynamics of Metal Complexes
No full textRationally designed Eu(III) complexes can be exploited as probes in the detection of analytes in biological fluids, by means of luminescence [1]. These complexes must be stable in aqueous solution, absorb and efficiently transfer the UV excitation to the metal ion (antenna effect). We succeeded to obtain this goal by including isoquinoline antenna into the ligand backbone. In fact, the luminescence of [Eu(bisoQcd)]+ and Eu(isoQC3A) complexes significantly increases in the presence of the main analytes which constitute the interstitial extracellular fluid (i.e. hydrogen carbonate, serum albumin (SA) and citrate) [2-4].The optical response of our Eu(III)-based probes is selective towards citrate molecule, when a complex matrix is considered. Citrate molecule is a very important bio-analyte and the monitoring of its concentration is crucial in order to identify the presence of a disease [5]. When a simulated interstitial extracellular fluid is employed, the change of the citrate concentration gives rise to an increase of the Eu(III) luminescence emission intensity of [Eu(bisoQcd)]+. On the other hand, negligible or no change of the luminescence intensity was detected when the concentration of both hydrogen carbonate and SA is changed. This is due to citrate capacity to displace a higher number of water molecules giving a distinctive increase of the luminescence intensity. Moreover, the Eu(III) intrinsic quantum yield of the adduct is higher.The obtained results candidate our europium complexes as viable probes for luminescence analysis of biofluids with complex matrix.
Acknowledgments: The work was financially supported by PRIN project "CHIRALAB", grant n. 20172M3K5N.
References:
[1]J.-C.G. Bünzli, Chem. Rev. 2010, 110 (5), 2729-2755.
[2]F. Piccinelli, C. De Rosa, A. Melchior, G. Faura, M. Tolazzi, M. Bettinelli, Dalton Trans. 2019, 48 (4),1202-1216.
[3]C. De Rosa, A. Melchior, M. Sanadar, M. Tolazzi, A. Giorgetti, R. P. Ribeiro, C. Nardon, F.Piccinelli, Inorg Chem. 2020, 59 (17), 12564-12577.
[4]C. De Rosa, A. Melchior, M. Sanadar, M. Tolazzi, A. Duerkop, F. Piccinelli, Dalton Trans. 2021, 50 (13),4700-4712.
[5]L. C. Costello, R. B. Franklin, Prostate Cancer Prostatic Dis. 2009, 12 (1), 17-24
A novel luminescent Europium(III) complexes for citrate detection.
No full textRationally designed Eu(III) complexes can be exploited as probes in the detection of analytes in biological fluids, by means of luminescence.[1] These complexes must be stable in aqueous solution, absorb and efficiently transfer the UV excitation to the metal ion (antenna effect). We succeeded to obtain this goal by including isoquinoline antenna into the ligand backbone. In fact, the luminescence of [Eu(bisoQcd)]+ (Figure 1) and Eu(isoQC3A) complexes significantly increases in the presence of the main analytes which constitute the interstitial extracellular fluid (i.e. hydrogen carbonate, serum albumin (SA) and citrate).[2,3]. Eu(III) complex suitable for citrate sensing The optical response of our Eu(III)-based probes is selective towards citrate molecule, when a complex matrix is considered. Citrate molecule is a very important bio-analyte and the monitoring of its concentration is crucial in order to identify the presence of metabolic disease.[4] When a simulated interstitial extracellular fluid is employed, the change of the citrate concentration gives rise to an increase of the Eu(III) luminescence emission intensity of [Eu(bisoQcd)]+. On the other hand, negligible or no change of the luminescence intensity was detected when the concentration of both hydrogen carbonate and SA is changed. This is due to citrate capacity to displace a higher number of water molecules giving a distinctive increase of the luminescence intensity. Moreover, the Eu(III) intrinsic quantum yield of the adduct is higher.
The obtained results candidate our europium complexes as viable probes for luminescence analysis of biofluids with complex matrix.
Acknowledgments: The work was financially supported by PRIN project "CHIRALAB", grant n.
20172M3K5N.
[1] J.-C.G. Bünzli, Chem. Rev. 2010, 110, 2729.
[2] C. De Rosa, A. Melchior, M. Sanadar, M. Tolazzi, A. Giorgetti, R. P. Ribeiro, C. Nardon, F.
Piccinelli, Inorg Chem. 2020, 59, 12564.
[3] C. De Rosa, A. Melchior, M. Sanadar, M. Tolazzi, A. Duerkop, F. Piccinelli, Dalton Trans. 2021, 50, 4700.
[4] L. C. Costello, R. B. Franklin, Prostate Cancer Prostatic Dis. 2009, 12, 1
Luminescent Eu(III) complexes as probes for citrate sensing in complex matrix.
No full textRationally designed Eu(III) complexes can be exploited as probes in the detection of important analytes in biological fluids, by means of luminescence.[1] These complexes must be stable in aqueous solution, absorb and efficiently transfer the UV excitation to the metal ion (antenna effect). We succeeded to obtain this goal by including isoquinoline antenna into the ligand backbone. In fact, the luminescence of [Eu(bisoQcd)]+ and Eu(isoQC3A) complexes significantly increases in the presence of the main analytes which constitute the interstitial extracellular fluid (i.e. hydrogen carbonate, serum albumin (SA) and citrate at their typical concentration).[2,3]
The optical response of our Eu(III)-based probes is selective towards citrate molecule, when a complex matrix is considered. Citrate molecule is a very important bio-analyte and since it is involved in many metabolic pathway, the monitoring of its concentration is crucial in order to identify the presence of metabolic disease.[4] When a simulated interstitial extracellular fluid is employed, the change of the citrate concentration gives rise to an increase of the Eu(III) luminescence emission intensity of [Eu(bisoQcd)]+. On the other hand, negligible or no change of the luminescence intensity was detected when the concentration of both hydrogen carbonate and SA is changed. Such a finding opens up the possibility to determine quantitatively the citrate anion in complex matrices up to concentrations of 500 μM.
Actually, all the main analytes present in this biological fluid show a similar affinity for the Eu(III) complexes and directly interact with the metal ion displacing a variable number of water molecules from the inner coordination sphere. As well known, this phenomenon produces a peculiar increase of the luminescence intensity stemming from Eu(III). Differently than hydrogen carbonate and SA, we demonstrate that citrate is capable to displace a higher number of water molecules giving a distinctive increase of the luminescence intensity. Moreover, the Eu(III) intrinsic quantum yield of the adduct is higher.
The obtained results candidate our europium complexes as viable probes for luminescence analysis of biofluids with complex matrix.
Acknowledgments: The authors thank the Italian Ministry of education, university and research for the received funds (PRIN (Progetti di Ricerca di Rilevante Interesse Nazionale) project "CHIRALAB", grant n. 20172M3K5N).
References:
[1] J.-C.G. Bünzli, Chem. Rev. 2010, 110 (5), 2729-2755.
[2] C. De Rosa, A. Melchior, M. Sanadar, M. Tolazzi, A. Giorgetti, R. P. Ribeiro, C. Nardon, F. Piccinelli, Inorg Chem. 2020, 59 (17), 12564-12577.
[3] C. De Rosa, A. Melchior, M. Sanadar, M. Tolazzi, A. Duerkop, F. Piccinelli, Dalton Trans. 2021, 50 (13), 4700-4712.
[4] L. C. Costello, R. B. Franklin, Prostate Cancer Prostatic Dis. 2009, 12 (1), 17-24
Coordination behavior of Ar-SO2-N-amino acids toward the Mn(II) ion. Crystal and molecular structure of [Mn(tsgln)2] and [Mn(ts-a-ala)2(H2O)]2.78H2O0.92CH3OH
No full textA series of complexes of Ar-SO2-N-amino acids (Ar-SO2-= 4-toluensulfonyl- (hereafter abbreviated as tosyl) (ts), benzenesulfonyl (bs); amino acid=glycine (gly), DL-alpha- and beta-alanine (alpha- and beta-ala), asparagine (asn) and glutamine (gln)) with Mn(II) was synthesized and characterized by means of spectroscopic and thermal analyses. For two of them [Mn(ts-alpha-ala)2(H2O)].2.78H2O.0.92CH3OH (1) and [Mn(tsgln)2] (II) the crystal and molecular structure was also determined. I crystallizes in the orthorhombic Pbcn space group, with cell dimensions: a = 31.212(3), b = 11.248(2), c = 9.051(2) angstrom, Z = 4. II crystallizes in the monoclinic C2 space group, with cell dimensions: a = 17.490(3), b = 5.259(2), c = 17.432(2) angstrom, beta = 120.70(4)-degrees, Z = 2. In both compounds the Mn(II) atom is octahedrally coordinated by six oxygen atoms. In I the amino acid monoanion bridges two Mn atoms through the carboxyl group giving rise to a 1D polymer, the coordination to Mn is completed by two water molecules in a special position. In II each amino acid monoanion bridges two Mn atoms through the carboxyl group and binds a third Mn atom through the carbonyl oxygen of the terminal amide group, giving rise to a 2D polymer
The thermodynamics of 1,4,7,10,13 - pentaazatridecane complexes of silver(I) in dimethyl sulfoxide.
No full textThe thermodynamic parameters Delta G degrees, Delta H degrees and Delta S degrees for the formation of silver(I) mononuclear (AgL(+)) and polynuclear ([Ag(2)L](2+), [Ag(3)L(2)](3+)) complexes with 1,4,7,10,13-pentaazatridecane (L = tetren) have been obtained in dimethyl sulfoxide (dmso) at 25 degrees C and in an ionic medium of 0.1 mol dm(-3). The complexes are enthalpy stabilized while the entropy contributions oppose their formation. Tetren, differently from other linear polyamines which have only aminoethylenic subunits and less than Eve nitrogens, is able to form polynuclear species in dmso. Structures and stabilities of the complexes are discussed in relation to the characteristics of the ligan
Thermodynamic and Spectroscopic Studies on the Complexation of Silver(I) by Mixed Phosphorus-Sulfur Compounds in Propylene Carbonate. Crystal and Molecular Structure of a Silver(I)-Thiophosphine Complex.
No full textThe thermodynamic parameters for complexation of silver(I) with the mixed-donor compounds Ph(2)PCH(2)SPh and Ph(2)P(CH2)(2)SR (R = Me, Et or Ph) have been determined by potentiometric and calorimetric techniques in propylene carbonate at 25 degrees C and 0.1 mol dm(-3) ionic strength (NEt(4)ClO(4)). Within the silver(I) concentration range investigated, Ph(2)PCH(2)SPh forms three successive mononuclear complexes whereas also polynuclear species are formed by the other thiophosphines. All the complexes are strongly enthalpy stabilized, the entropy changes being unfavourable. The ligands behave as either monodentate (through P) or bidentate. depending upon the length of the aliphatic chain between the donor atoms and on the stoichiometry of the species formed. The influence of R on the stabilities of the complexes is discussed. The crystal structure of the 1:1 Ag-Ph(2)P(CH2)(2)SEt complex has been determined: monoclinic. space group P2(1)/c, a = 8.924(2), b = 9.620(1), c = 44.797(6) Angstrom, beta = 93.41(1)degrees and Z = 4. Phosphorus-31 NMR studies have also been performed to obtain additional information on the nature and structure of the species formed. Comparison of the thermodynamic data for formation of the silver(I) complexes with the same ligands in dimethyl sulfoxide evidences a different behaviour of the ligands in the two media: the results are discussed in terms of the different physicochemical properties of the two solvents
Calorimetric and fluorimetric interaction studies of Europium(III) complexes with Bovine Serum Albumin.
No full textLanthanide (Ln(III)) derivatives, mainly Eu(III) and Tb(III) complexes, have been broadly exploited as sensors in physiological conditions for the detection of relevant clinical biomarkers.[1] This can be done thanks to their peculiar properties such as long Ln(III) luminescence lifetime and the so called antenna effect. The luminescent Ln(III) complex must interact selectively with a target bioanalyte competing with species, such as proteins. Serum albumins, which represent 52% of the protein composition in the circulatory system, play many physiological and pharmacological functions in the delivery of a variety of endogenous and exogenous species. Human serum albumin (HSA) and Bovine serum albumin (BSA) are the most studied serum albumins, and classified as homologous proteins. Changes of the albumin levels in blood could be a sign of several disorders,
such as liver disease, neoplasia and more [2].
With the aim to assess the interaction of some Eu(III) luminescent complexes with the BSA and thus the possible competition with other analytes, fluorescence/luminescence titrations with the cited protein were carried out in this work, the ligands employed differ for their antenna moieties. In addition, the thermodynamics of the interactions were studied by isothermal titration calorimetry (ITC).
The protonation constants for the ligands alone and their formation constants with Eu(III) have been determined by potentiometric and spectrophotometric techniques [3], the
fluorescence/luminescence titrations and ITC titrations of the complexes with BSA have been run at pH = 7.4 (MOPS buffer). The results obtained by ITC measurements, indicated
negative enthalpy values for the interaction with BSA.
Computational methods provided additional information about the formed adducts: in particular, EuL (L =bpcd and bisoQcd) complexes form adducts with BSA with different stoichiometry, which result from different interaction mechanism. Also, as showed by competitive titrations with site markers (warfarin/ibuprofen/digitoxin) and Molecular Docking/Molecular Dynamics Simulations, the interaction with BSA occurs at different sites for Eu(bpcd) and Eu(bisoQcd) [4].
Bibliography
[1] Piccinelli F., De Rosa C., Melchior A., Faura G., Tolazzi M., Bettinelli M. Eu(iii) and Tb(iii)
complexes of 6-fold coordinating ligands showing high affinity for the hydrogen carbonate ion: a spectroscopic and thermodynamic study, Dalt. Trans., 2019, 48, 1202–1216.
[2] Volkova K.D., Kovalska V.B., Losytskyy M.Y., Bento A., Reis L.V., Santos P.F., Almeida P.,
Yarmoluk S.M. Studies of benzothiazole and benzoselenazole squaraines as fluorescent probes for albumins detection, J. Fluoresc. 2008, 18, 877–882.
[3] Leonzio M., Melchior A., Faura G., Tolazzi M., Bettinelli M., Zinna F., Arrico L., Di Bari L., Piccinelli F. A chiral lactate reporter based on total and circularly polarized Tb(iii) luminescence, New J. Chem. 2018, 42, 7931–7939.
[4] De Rosa C., Melchior A., Sanadar M., Tolazzi M., Giorgetti A., Ribeiro R.P., Nardon C., Piccinelli F. Effect of the Heteroaromatic Antenna on the Binding of Chiral Eu(III) Complexes to Bovine Serum Albumin, Inorg. Chem. 2020, 59, 12564–12577
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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