Publications

Abstract RAC1b is a hyperactive variant of the small GTPase RAC1 known to be a relevant molecular player in different cancers. Previous studies from our group lead to the evidence that its overexpression in papillary thyroid carcinoma (PTC) is associated with an unfavorable prognosis. In the present study, we intended to extend the analysis of RAC1b expression to thyroid follicular neoplasms and to seek for clinical correlations. RAC1b expression levels were determined by RT-qPCR in thyroid follicular tumor samples comprising 23 follicular thyroid carcinomas (FTCs) and 33 follicular thyroid adenomas (FTAs). RAC1b was found to be overexpressed in 33% of carcinomas while no RAC1b overexpression was documented among follicular adenomas. Patients with a diagnosis of FTC were divided into two groups based on longitudinal evolution and final outcome. RAC1b overexpression was significantly associated with both the presence of distant metastases (P = 0.01) and poorer clinical outcome (P = 0.01) suggesting that, similarly to that previously found in PTCs, RAC1b overexpression in FTCs is also associated with worse outcomes. Furthermore, the absence of RAC1b overexpression in follicular adenomas hints its potential as a molecular marker likely to contribute, in conjunction with other putative markers, to the preoperative differential diagnosis of thyroid follicular lesions.

Abstract In this paper, we investigate the nature of the carbonyl and the intraring C-C, C-N, C-O, N-N, O-O and N-O bonds of cyclopropanone and the following cyclopropanone derivatives: aziridine-2-one (1); oxirane-2-one (2); 1,2-diaziridine-3-one (3); 1,2-dioxirane-3-one (4); 1,2-oxaziridine-3-one (5); cyclopropane-1,2-dione (6); aziridine-2,3-dione (7); and oxirane-2,3-dione (8). The intramolecular distribution of the electronic charge density and the L(r) = -A1/4a double dagger(2) rho(r) function have been investigated within the framework of the quantum theory of atoms in molecule theory. This methodology allowed us to characterize the bonds of cyclopropanone and the cyclopropanone derivatives studied here.

Abstract Carbon dots (CDs) were prepared from citric acid and urea, and their fluorescence was found to be quenched by hypochlorite and peroxynitrite. Microwave based synthesis gives CDs with excitation/emission wavelength-dependent quantum yields (8 % at 400/520 nm; 10 % at 360/451 nm; 12 % at 350/420 nm). Quenching of fluorescence depends on pH values, and response is most selective and sensitive to hypochlorite at pH 4, and to peroxynitrite at pH 9. The lower detection limits are 0.5 and 1.5 mu M, respectively. The method was successfully applied to quantify hypochlorite and peroxynitrite in standard solutions and in spiked dilute serum samples.

Abstract We present herein the synthesis, and the structural and spectroscopic analysis of a non-planar tripod-shaped p-(N,N'-dimethylamino) benzyliden-1,3-indandione (DMABI) chromophore. This novel molecule is composed of a Si core with three incorporated arms, each of them contains a 1,3-indandione derivative with an electron donating (-NMe2) group, thus providing fluorescence capabilities. We prepared a DMABI arm by coupling a p-(N,N'-dimethylamino) benzaldehyde (DMAB) tripod substituted molecule with 1,3-indandione via aldol condensation. The structures of DMAB-tripods were confirmed by spectroscopic data and studied by quantum chemical calculations. Fluorescence spectroscopy was used for optical characterization. Quantum yields and the corresponding lifetimes reveal typical characteristics of conjugated derivatives. Finally, we monitored the enhancement in fluorescence intensity of compound 1 in the presence of 4-chloro-2,6-dinitroaniline (4CDNA) in the range between 0 and 20 mg L-1. We justify this enhancement by calculated energies and the distribution of the HOMO and the LUMO for DMABI-tripod and 4CDNA.

Abstract The thermodynamics and phase behavior of mixtures of cationic gemini surfactant decanediyl-alpha, omega-bis(dodecyldimethylammonium bromide) (12-10-12) and sodium dodecylsulfate (SDS) were studied in the dilute SDS-rich region. The enthalpy of interaction between both surfactant monomers before the critical micelle concentration for the mixture (cmc(mix)) was determined by isothermal titration calorimetry (ITC). After the cmc(mix), ITC results exhibited a first process associated with a large endothermic enthalpy change followed by a second one with a very small exothermic enthalpy change. In the same regions, the conductivity curves show an increase in slope after the break, followed by a plateau region, respectively for the two processes. The combined results from the various methodologies used lead us to propose that the first process reflects the formation of non-spherical micelles and the second one the vesicle formation. The area per catanionic complex was obtained through surface pressure measurements, leading to an apparent packing parameter >= 1. The observed behavior may be rationalized on the basis of the hypothesis that both surfactants distribute asymmetrically in the vesicle bilayers and unevenly in the non-spherical micelle. In order to get structural information Cryo-TEM experiments were performed, which provided images that support this interpretation. From all the information gathered a phase diagram was mapped, including three one-phase regions of spherical micelles, non-spherical micelles and vesicles.

Abstract Steady-state and time-resolved fluorescence techniques, in addition to quantum mechanical calculations, were employed to study the excited-state proton transfer (ESPT) to solvent of three 7-hydroxycoumarin dyes. We found that for 7-hydroxycoumarins in water, the ESPT rate is high, about 2 X 10(10) s(-1), whereas in methanol the ESPT rate is much lower than that over the nonradiative lifetime of the excited singlet state; thus, the ESPT efficiency is very low.

Abstract The heat capacities in the temperature range (5 to 370) K and the parameters of solid-phase transitions and fusion were determined for three [C(n)mim][NTf2] (n = 10, 14, 16) ILs. The temperature-dependent vapour pressures of [C(14)mim][NTf2] and [C(16)mim][NTf2] were measured with a Knudsen effusion apparatus combined with a quartz crystal microbalance. Thermodynamic properties of these compounds in the crystal, liquid, and gas states were derived from the obtained data. The results obtained in this work were combined to those available in the literature for the short-chain homologues to discuss regularities in thermodynamic properties of the series. While some properties demonstrate simple linear dependence on the alkyl chain length, a more complicated behaviour with strong non-linearity or a break at n = 6 is observed for others. Published by Elsevier Ltd.

Abstract The thermal behavior, solid and liquid heat capacities of the 1-benzyl-3-methylimidazolium, [Bzmim](+), based ionic liquid series with Cl, PF6, BF4, CHF2CF2SO3 and NTf2 as anions were used to evaluate the effect of the insertion of an aromatic character (benzyl group) and the expected increase of the pi-pi interactions as well as the impact in the cation-anion hindrance and charge delocalization in the ionic liquid properties. It was found that the molar liquid heat capacities of [Bzmim][X] are in the same order as the 1-pentyl-3-methylimidazolium, [C(5)C(1)im][X] analogs. A good correlation between the molar (solid and liquid) heat capacity and the number of atoms of the anion was found. Two different crystalline forms for [Bzmim][BF4] differing by 10 K in the melting temperature and about 10% in the heat capacity were found. The crystallization behavior, melting temperatures, and enthalpies and entropies of fusion show that the insertion of an aromatic character (benzyl group) in the imidazolium cation leads to a significant and systematic change of the thermophysical properties of the ionic liquids associated with an increase of the glass transition and melting temperatures arising from the additional pi-pi interactions. (C) 2016 Published by Elsevier Ltd.

Abstract Aryl derivatives of ferrocene are used for the modification of graphitic surfaces. Stronger adsorption is utilized as a route to enable the electrochemically tagging of new carbon materials. Model experiments are reported on an EPPG electrode where the adsorption of 1-(biphen-4-yl)ferrocene is found to be a factor of ca. 5 times more thermodynamically favorable than the underivatised form. Two further derivatives were also studied and the voltammetric responses of this class of ferrocenes are found to be significantly influenced by ion-pairing. Finally, the successful use of these new materials for the modification and redox tagging of graphene nanoplatelets is demonstrated.