Silvia Biagini

University of Florence, Florence, Tuscany, Italy

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Publications (14)56.3 Total impact

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    ABSTRACT: To investigate radiological sacroiliac abnormalities in IBD patients without musculoskeletal symptoms and to determine the clinical and familiar differences between IBD patients with and without radiologic sacroiliac joint (SIJ) abnormalities. Subsequently, the patients with x-ray alterations were followed for 3 years in order to assess the onset of chronic inflammatory back pain (IBP).
    Clinical and experimental rheumatology 08/2014; · 2.66 Impact Factor
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    ABSTRACT: To investigate the presence of lower limb entheseal abnormalities in IBD patients without clinical signs and symptoms of SpA and their correlation with IBD clinical variables. A total of 81 IBD patients [55 Crohn's disease (CD) and 26 ulcerative colitis (UC), 43 females and 38 males, mean age 41.3 (12.4) years, BMI 24 (2)] with low active (12) and inactive (67) disease were consecutively studied with US (LOGIQ5 General Electric 10-MHz linear array transducer) of lower limb entheses and compared with 40 healthy controls matched for sex, age and BMI. Quadriceps, patellar, Achilleon and plantar fascia entheses were scored according to the 0-36 Glasgow Ultrasound Enthesitis Scoring System (GUESS) and power Doppler (PD). Correlations of GUESS and PD with IBD features [duration, type (CD/UC) and activity (disease activity index for CD/Truelove score for UC)] were investigated. The intra- and inter-reader agreements for US were estimated in all images detected in patients and controls. Of the 81 patients, 71 (92.6%) presented almost one tendon alteration with mean GUESS 5.1 (3.5): 81.5% thickness (higher than controls P < 0.05), 67.9% enthesophytosis, 27.1% bursitis and 16.1% erosions. PD was positive in 13/81 (16%) patients. In controls, US showed only enthesophytes (5%) and no PD. GUESS and PD were independent of duration, activity or type (CD/UC) of IBD. The intra- and inter-reader agreements were high (>0.9 intra-class correlation variability). US entheseal abnormalities are present in IBD patients without clinical signs and symptoms of SpA. US enthesopathy is independent of activity, duration and type of gut disease.
    Rheumatology (Oxford, England) 02/2011; 50(7):1275-9. · 4.24 Impact Factor
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    ABSTRACT: New platinum(II) complex of 3,6-diamine-9-[6,6-bis(2-aminohethyl)-1,6-diaminohexyl]acridine, AzaPt, has been synthesised and characterised. Behaviour of AzaPt in solution (protonation and possible self-aggregation phenomena) has been investigated by spectral methods (absorbance and fluorescence) at I=0.1 M and 25 degrees C, and the equilibrium parameters of binding to calf thymus DNA have been established. Two different modes of DNA binding by the complex were detected, which depend on the polymer to dye molar ratio (P/D). At relatively low P/D values the mode was interpreted as binding by the polyamine residue external to the base pairs, while at high P/D values the binding corresponds to intercalation of the proflavine residue. Such interpretation is supported by the observed salt effect on binding and the temperature variation of the binding constants, which allowed estimating the Delta H and Delta S values contributions. Spectrophotometric analysis of the long time range binding revealed that AzaPt is involved in a slow reaction, interpreted as an attack by the platinum ion on the nucleobases. The time constant for such interaction was calculated and found to be the same order of magnitude as for processes responsible for the action of anti-tumour drugs that do covalently bind to polynucleotides. (C) 2010 Elsevier Inc. All rights reserved.
    Journal of inorganic biochemistry 12/2010; 105(4):558-562. · 3.25 Impact Factor
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    ABSTRACT: Ru(ii) complexes that bring together the properties of the dppz (dipyrido[3,2-a:2',3'-c]phenazine) intercalating residue and the properties of metal-coordinating macrocycles (L = 4,4'-(2,5,8,11,14-pentaaza[15])-2,2'-bipyridilophane) have been synthesised and their protonation and affinity for copper(ii) was analysed. Ru(bpy)(dppz)L(2+) (D2(2+)) and Ru(dppz)(2)L(2+) (D3(2+)) were found to interact with DNA but the binding mode is not simple and its features strongly depend both on the ligand structure and on the [DNA]/[complex] ratio. Equilibrium measurements (spectrophotometric and spectrofluorometric titrations), kinetics (stopped-flow technique) and theoretical calculations all concur in suggesting that for the less hindered D2(2+) an important contribution of external binding, driven by dye-dye interactions, is operative, as revealed by the onset of positive cooperativity. On the contrary, for the bulkier D3(2+) complex dye-dye interactions are less effective, resulting in an intercalation process with lower dppz penetration within DNA slots. The Ru(bipy)(2)L(2+)(D1(2+))/DNA system was also analysed for comparison and helped in showing the non negligible contribution of the macrocycle to the binding process. The binding affinities of the macrocycle copper complexes for DNA are lower than those of their copper-free analogues only in the case of D1(2+), whereas an affinity enhancement in agreement with the charge increase upon copper coordination is observed for D2(2+) and D3(2+). Copper coordination produces complete loss of the cooperative behaviour in the case of D2(2+). Further mechanistic details are discussed.
    Dalton Transactions 11/2010; 39(41):9838-50. · 3.81 Impact Factor
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    ABSTRACT: The new macrocyclic ligand 1,9(4,7)-diphenanthroline-3,7,11,15-tetraazacyclohexadecaphane (L) was synthesized by a 2 : 2 reaction of 1,10-phenanthroline-4,7-dialdehyde with 1,3-diaminopropane, followed by reduction with NaBH(4). L contains two phenanthroline groups linked together by two 1,3-diaminopropane chains in such a way that the heteroaromatic nitrogen atoms point outside the ligand cavity. The ligand structure defines two pairs of identical compartments displaying a specific ability in the binding of protons (1,3-diaminopropane) and metal ions (phenanthroline). Protonation and Zn(II) coordination were studied by means of potentiometric and spectroscopic ((1)H NMR, UV-vis, fluorescence) techniques. Both protonation and Zn(II) coordination consistently affect the fluorescence emission properties of L, giving rise to enhancement or quenching of the emission, depending on the species involved. L becomes emissive upon protonation, but the formation of the highly protonated species, in particular the fully protonated [H(6)L](6+), quenches the emission. The mono- and dinuclear Zn(II) complexes of the unprotonated ligand are non-emissive, like free L, while Zn(II) binding to [HL](+) activates the emission. The most interesting aspect, however, is the chelation enhancement of quenching (CHEQ) observed upon Zn(II) binding to [H(2)L](2+) and [H(4)L](4+), being among the few examples of CHEQ effect observed for Zn(II) complexes. Hydrogen bonding between a metal coordinated water molecule and a phenanthroline group seems to be responsible for the CHEQ observed for [ZnH(2)L](4+).
    Dalton Transactions 10/2010; 39(42):10128-36. · 3.81 Impact Factor
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    ABSTRACT: Proton and Cu(II), Zn(II), Cd(II) and Pb(II) binding by ligand H(2)L, containing two bis(aminoethyl)amine (dien) units connected by a 2',7'-dichlorofluorescein (DCF) unit has been analyzed by means of potentiometric, UV-vis and fluorescence emission measurements. Considering proton binding, the ligand in its fully deprotonated form, L(2-), binds up to four acidic protons in the alkaline pH region. These protonation steps occur on the amine groups, whereas protonation of DCF takes place only below pH 4. In metal complexation, the ligand displays a marked selectivity for Zn(II) over Cd(II) and Pb(II), due to the better accommodation of the smaller and harder Zn(II) ion within the binding pocket generated by a dien unit and the adjacent deprotonated oxygen. The fluorescence emission study points out that Zn(II) binding is accompanied by a marked increase of the DCF emission from neutral to slightly alkaline pH values, where protonated forms of the complex are present in solution. The system is weakly emissive at slightly acidic pH values, where Zn(II) is essentially not bound to the receptor and above pH 9.5, probably due to the formation of the not protonated [ZnL] complex. Cd(II) binding gives rise to a much less intense increase of the emission only above pH 8.5, whereas Cu(II) and Pb(II) complexation leads to fluorescence quenching. Furthermore, the interaction of H(2)L with cells was investigated to explore its application as a new sensor for the evaluation of cellular Zn(II) content and distribution.
    Dalton Transactions 08/2010; 39(30):7080-90. · 3.81 Impact Factor
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    ABSTRACT: The synthesis of receptor 2,6,10,14,18-pentaaza[20]-21,34-phenanthrolinophane (L1), containing a pentaamine chain linking the 2,9 positions of a phenanthroline unit, is reported. The protonation features of L1 and of receptor 2,6,10,14,18,22-hexaaza[23]-24,37-phenanthrolinophane (L2) have been studied by means of potentiometric, (1)H NMR, and spectrofluorimetric measurements; this study points out that the fluorescent emission of both receptors depends on the protonation state of the polyamine chain. In fact, the receptors are emissive only at neutral or acidic pH values, where all the aliphatic amine groups are protonated. Potentiometric titrations show that L2 is able to bind selectively ATP over TTP, CTP, and GTP. This selectivity is lost in the case of L1. (1)H and (31)P NMR measurements and molecular mechanics calculations show that the phosphate chains of nucleotides give strong electrostatic and hydrogen-bonding interactions with the ammonium groups of the protonated receptors, while the nucleobases interact either via pi-stacking with phenanthroline or via hydrogen bonding with the ammonium groups. Of note, MM calculations suggest that all nucleotides interact in an inclusive fashion. In fact, in all adducts the phosphate chain is enclosed within the receptor cavities. This structural feature is confirmed by the crystal structure of the [(H(6)L2)(2)(TTP)(2)(H(2)O)(2)](4+) adduct. Fluorescence emission measurements at different pH values show that L2 is also able to ratiometrically sense ATP in a narrow pH range, thanks to emission quenching due to a photoinduced electron transfer (PET) process from an amine group of the receptor to the excited phenanthroline.
    The Journal of Organic Chemistry 10/2009; 74(19):7349-63. · 4.56 Impact Factor
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    ABSTRACT: Synthesis, characterisation and proton-sponge behaviour of a new linear constrained tris-macrocycle (L), containing three cyclen (cyclen = 1,4,7,10-tetraazacyclododecane) reinforced macrocycles connected by two 2,6-pyridinediylbis(methylene) linkers, is reported. Protonated forms of L are efficient receptors for inorganic phosphate and nucleotide anions (ATP and ADP). The binding properties of L toward these substrates have been investigated in aqueous solution by means of potentiometric titrations, determining the stability constants of the adducts. The interaction mode was clarified by using 1H and 31P NMR measurements in aqueous solution and by means of molecular modelling calculations carried out on differently protonated species of L as well as on several nucleotide-receptor adducts. The stability of the adducts is mainly due to charge-charge and hydrogen bonding interactions between the polyphosphate chain of nucleotides and the ammonium groups of L.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
    Annalen der Chemie und Pharmacie 09/2009; 2009(32):5610 - 5621. · 3.10 Impact Factor
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    ABSTRACT: The synthesis of the macrocyclic receptor L1, which contains a tetraamine chain linking the 6,6'-positions of a 2,2'-dipyridine moiety, is reported. Its basicity properties and complexation features toward Cu(II), Zn(II), Cd(II) and Pb(II) have been studied in aqueous solutions by means of potentiometric, UV/Vis spectroscopy and fluorescence emission measurements and compared with those of ligand L2, in which a 1,10-phenanthroline moiety replaces the dipyridine unit of L1. In metal coordination, L1 shows a marked selectivity toward Cd(II) over Zn(II) and Pb(II). The crystal structures of its metal complexes shows that L1 possesses a preferential tetradentate binding site for metal cations, composed of the dipyridine unit and the two adjacent benzylic amine groups. This binding site has the proper dimension and conformation to selectively coordinate the Cd(II) ion, as confirmed by DFT calculations carried out on the complexes. This coordinative zone is lost in L2. The rigidity of phenanthroline does not allow the simultaneous binding of both the benzylic amine groups to Zn(II) and Cd(II) and, in fact, one benzylic amine is not coordinated to these metal cations. The fluorescence emission properties of the L1 and L2 complexes are strongly pH dependent. Only the Zn(II) and Cd(II) complexes with L1 display fluorescence emission at neutral pH. This feature is related to the formation in solution at pH 7 of emissive protonated complexes of the type [M(H(x)L)]((2+x)+) (x=1-3), in which all the nitrogen donors are involved in metal or proton binding. The emissive characteristics of these protonated complexes are confirmed by the fluorescence emission spectra collected on the [Zn(HL1)Br][ClO(4)](2) and [Cd(HL1)Br][ClO(4)](2) solid compounds dissolved in CH(3)CN. Conversely, the Zn(II) and Cd(II) complexes with L2 are not emissive; in fact, they contain a benzylic amine group not involved in metal or proton binding that can quench the fluorescence emission of the fluorophore, thanks to a photoinduced electron-transfer process.
    Chemistry 07/2009; 15(32):8049-63. · 5.93 Impact Factor
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    ABSTRACT: The synthesis and characterisation of a new macrocyclic compound (L), composed of a pentamine chain linking the 2,7 positions of an acridine moiety, is reported. Cu(ii) complexation was studied by means of potentiometric, UV-vis and EPR measurements in aqueous solutions. This study reveals that the ligand forms a stable tetranuclear complex with an overall [Cu(4)L(2)(OH)(4)](4+) stoichiometry in aqueous solution. The crystal structure of the [Cu(8)L(4)(micro-OH)(8)(micro-NO(3))(3)](NO(3))(5).32H(2)O complex, isolated from neutral aqueous solution, shows that it is formed by tetranuclear clusters [Cu(4)L(2)(micro-OH)(4)(micro-NO(3))(x)]((4-x)+) (x= 1 or 2), composed of two [Cu(2)L](4+) macrocyclic units linked together by four bridging hydroxide and nitrate anions to give an overall metallomacrocyclic structure. Magnetic measurements shows that the hydroxide-bridged Cu(ii) ions are ferromagnatically coupled. Inspection of the crystal packing shows that couples of metallomacrocycles are paired by pi-stacking interactions between acridine moieties, giving rise to an internal hydrophilic cavity were hexameric or pentameric water clusters are enclosed. The coupled metallomacrocycles assume a columnar disposition growing along the a axis, giving rise to channels passing through the cavities of the metallomacrocycles; these channels are filled by chains of 5- or 6-membered water clusters linked together by [NO(3).H(2)O](2) units.
    Dalton Transactions 03/2009; · 3.81 Impact Factor
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    ABSTRACT: Two new mixed aza-thia crowns 5-aza-2,8-dithia[9]-(2,9)-1,10-phenanthrolinophane (L(4)) and 2,8-diaza-5-thia[9]-(2,9)-1,10-phenanthrolinophane (L(7)) have been synthesized and characterized. The coordination behavior of L(4) and L(7) toward the metal ions Cu(II), Zn(II), Pb(II), Cd(II), Hg(II), and Ag(I) was studied in aqueous solution by potentiometric methods, in CD3CN/D2O 4:1 (v/v) by (1)H NMR titrations and in the solid state. The data obtained were compared with those available for the coordination behavior toward the same metal ions of structurally analogous mixed donor macrocyclic ligands L(1)-L(3), L(5), L(6): all these contain a phenanthroline subunit but have only S/O/N(aromatic) donor groups in the remaining portion of the ring and are, therefore, less water-soluble than L(4) and L(7). The complexes [Cd(NO3)2(L(5))], [Pb(L(7))](ClO4)2 x 1/2MeCN, [Pb(L(4))](ClO4)2 x MeCN, and [Cu(L(7))](ClO4)2 x 3/2MeNO2 were characterized by X-ray crystallography. The efficacy of L(1)-L(7) in competitive liquid-liquid metal ion extraction of Cu(II), Zn(II), Cd(II), Pb(II), Ag(I), and Hg(II) was assessed. In the absence of Hg(II), a clear extraction selectivity for Ag(I) was observed in all systems investigated.
    Inorganic Chemistry 10/2008; 47(18):8391-404. · 4.59 Impact Factor
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    ABSTRACT: A dizinc complex with a polyamine macrocycle is able to selectively bind and sense uridine (U) as well as the uridine-containing ribodinucleotides U(3'-5')pU and U(3'-5')pA, thanks to an exciplex emission arising from a pi-stacked complex involving the dipyridine unit and Zn(II)-bound uridine moieties.
    Chemical Communications 04/2007; · 6.38 Impact Factor
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    ABSTRACT: A new polyammonium receptor is able to selectively recognise and sense ATP among triphosphate nucleotides, thanks to ATP-induced quantitative quenching of its fluorescence emission.
    Chemical Communications 11/2006; · 6.38 Impact Factor
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    ABSTRACT: The new ligand L consisting of a 1,10-phenanthroline unit bearing in 2,9 positions two triamine branches with terminal naphthalene groups was synthesized and used for protonation and metal ion (Zn(II), Cd(II), Pb(II)) coordination studies. Protonation and metal ion coordination were analyzed by means of potentiometric measurements, affording speciation of the systems and determination of the relevant equilibrium constants, and by means of H-1 NMR, UV-Vis and fluorescence emission spectroscopy. L forms stable complexes with the three metal ions showing very high selectivity for the binding of Zn(II) over Pb(II) (selectivity coefficient of 42,000 around pH 8.3), high selectivity for the binding of Cd(II) over Pb(II) (selectivity coefficient of 710 around pH 7.7) and modest selectivity for the bind of Zn(II) over Cd(II) (selectivity coefficient of about 70 around pH 9). Exciplex emission in the visible region due to the interaction of the coordinated phenanthroline unit with a naphthalene group is observed for the Zn(II) and Cd(II) complexes, while the Pb(II) complex is completely quenched. Such thermodynamic and photochemical properties define the conditions for selective sensing of Zn(II) and Cd(II) in the presence of Pb(II). (C) 2011 Elsevier B.V. All rights reserved.
    INORGANICA CHIMICA ACTA. 381:229-235.