169 research outputs found
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
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
Solvation of Co2+ ion in 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ionic liquid: A molecular dynamics and X-ray absorption study
No full textThe solvation of the Co2+ ion in the [C4mim][Tf2N] (1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide) room temperature ionic liquid (RTIL) has been studied from both a structural and thermodynamic point of view. Co K-edge X-ray absorption spectroscopy (XAS) data have been collected on a 0.1 M Co(Tf2N)2 solution in [C4mim][Tf2N] as well as on the metallic salt and classical MD simulations have been performed to obtain both structural and thermodynamic data. The analysis of the extended X-ray absorption fine structure (EXAFS) region of the spectrum of the liquid sample has been carried out with the aid of MD simulations showing that the [Co(Tf2N)6]4− complex is formed in solution. A different coordination is present in the solid compound, where Co2+ is coordinated by two bidentate and two monodentate anions to form a [Co(Tf2N)4]2− unit. Thermodynamic data obtained from free energy calculations provide a strongly negative solvation free energy (ΔGsolv) which is qualitatively similar to that previously found for the Zn2+ ion. Free energy calculations carried out at variable temperature provided negative values for both ΔΗsolv and ΔSsolv. Thermodynamic parameters for the water→[C4mim][Tf2N] ion transfer (ΔGtrans, ΔΗtrans and ΔStrans) have been also obtained. The positive ΔGtrans shows that Co2+ is preferentially solvated by water, in agreement with the spectral changes in the visible region occurring when water is added to a Co2+ solution in dry [C4mim][Tf2N] even at low H2O/metal ratios. At higher water concentrations (up to the saturation limit), the spectrum is compatible with the presence of the [Co(H2O)6]2+ species. Interestingly, the positive ΔGtrans results from a compensation between ΔΗtrans and ΔStrans, which are both negative. However, the ligand exchange energy calculated for the CoL6 complexes (L = [Tf2N]− and H2O) indicates that [Tf2N]− is a much weaker ligand than water. This evidence suggests that the energetic contributions to the overall solvation enthalpy due to outer sphere effects are markedly different in water and [C4mim][Tf2N], so that the final ΔHtrans results to be negative
Molecular interpretation of pharmaceuticals' adsorption on carbon nanomaterials: Theory meets experiments
No full textThe ability of carbon-based nanomaterials (CNM) to interact with a variety of pharmaceutical drugs can be exploited in many applications. In particular, they have been studied both as carriers for in vivo drug delivery and as sorbents for the treatment of water polluted by pharmaceuticals. In recent years, the large number of experimental studies was also assisted by computational work as a tool to provide understanding at molecular level of structural and thermodynamic aspects of adsorption processes. Quantum mechanical methods, especially based on density functional theory (DFT) and classical molecular dynamics (MD) simulations were mainly applied to study adsorption/release of various drugs. This review aims to compare results obtained by theory and experiments, focusing on the adsorption of three classes of compounds: (i) simple organic model molecules; (ii) antimicrobials; (iii) cytostatics. Generally, a good agreement between experimental data (e.g. energies of adsorption, spectroscopic properties, adsorption isotherms, type of interactions, emerged from this review) and theoretical results can be reached, provided that a selection of the correct level of theory is performed. Computational studies are shown to be a valuable tool for investigating such systems and ultimately provide useful insights to guide CNMs materials development and design
Secondary Mould Metabolites: Part 47. Isolation and Structure Elucidation of Clavilactones A-C, New Metabolites from the Fungus Clitocybe Clavipes
No full textThermodynamic study of Cd(II) complex formation with tripodal N-donor ligands in DMSO
No full textThe complex formation of Cd(II) with N-donor ligands in dimethylsulfoxide (DMSO) is investigated by means of potentiometry and titration calorimetry. The ligands considered in this work are tripodal polyamines and polypyridines: 2,2',2 ''-triaminotriethylamine (TREN), tris (2-( methylamino) ethyl) amine (Me(3)TREN), tris(2-(dimethylamino) ethyl) amine (Me(6)TREN), tris[(2-pyridyl) methyl] amine (TPA) and 6,6'-bis-[bis-(2-pyridylmethyl)aminomethyl]-2,2'-bipyridine (BTPA). These ligands are characterized by a systematic modification of the donor groups to relate their structure to the thermodynamics of the complexes formed. The TREN and Me(3)TREN ligands form highly stable species. The stability of the complex formed with the fully methylated Me(6)TREN is much lower than with other polyamines and the enthalpic and entropic terms suggest an incomplete coordination to the metal ion. In general, the TPA ligand forms complexes less stable than TREN and Me(3)TREN as a result of the combination of higher structural rigidity of TPA and lower basicity of pyridine moiety with respect to primary and secondary amines. Pyridine-containing ligands display, in general, a less unfavorable formation entropy than tripodal polyamines here considered. In particular, TPA forms a more stable 1: 1 species with respect to Me(6)TREN due to the entropic term, being the enthalpy less negative. The ligand BTPA is able to form only a monometallic complex, where the metal ion is likely to be encapsulated as indicated by the obtained thermodynamic parameters
Thermodynamics of complex formation of silver(I) with N-donor ligands in non-aqueous solvents
No full textThe results of a potentiometric and calorimetric study on the complexation reactions of neutral N-donor ligands with silver(I) in propylenecarbonate (PC) and dimethylformamide (DMF) are reported. The ligands concerned in DMF are butylamine (n-but), 1,2-diaminoethane (EN), bis(2-aminoethyl)amine (DIEN) and N,N’-bis(2-aminoethyl)ethane-1,2-diamine (TRIEN) whereas in PC results are provided for EN and DIEN, because of side reactions occurring for n-but and TRIEN. The data are compared to those previously reported in dimethylsulfoxide (DMSO), acetonitrile (AN) and water solvent media which present quite different dielectric constants (ε) and donor numbers (Dn). The trend of stabilities of the mononuclear AgL and AgL2 formed is discussed in terms of different cation and amines solvation in the different solvents. TRIEN can form bimetallic species in DMF, but not in DMSO. Given the lower ε value for DMF than for DMSO, Ag2TRIEN formation is evidently more influenced by the lower solvation of Ag(I) ion in DMF, rather than by difference in dielectric constants of these two solvents. In PC in addition to mononuclear complexes of higher stability with respect to the former solvents, also polynuclear Ag2L and Ag3L2 species are found
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