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2015
Zamora-Mora, V, Soares PIP, Echeverria C, Hernández R, Mijangos C.  2015.  Composite chitosan/agarose ferrogels for potential applications in magnetic hyperthermia. Gels. 1:69–80., Number 1: Multidisciplinary Digital Publishing Institute AbstractWebsite

Composite ferrogels were obtained by encapsulation of magnetic nanoparticles at two different concentrations (2.0 and 5.0 % w/v) within mixed agarose/chitosan hydrogels having different concentrations of agarose (1.0, 1.5 and 2.0% (w/v)) and a fixed concentration of chitosan (0.5% (w/v)). The morphological characterization carried out by scanning electron microscopy showed that dried composite ferrogels present pore sizes in the micrometer range. Thermogravimetric measurements showed that ferrogels present higher degradation temperatures than blank chitosan/agarose hydrogels without magnetic nanoparticles. In addition, measurements of the elastic moduli of the composite ferrogels evidenced that the presence of magnetic nanoparticles in the starting aqueous solutions prevents to some extent the agarose gelation achieved by simply cooling chitosan/agarose aqueous solutions. Finally, it is shown that composite chitosan/agarose ferrogels are able to heat in response to the application of an alternating magnetic field so that they can be considered as potential biomaterials to be employed in magnetic hyperthermia treatments.

Echeverria, C, Soares PIP, Robalo A, Pereira L, Novo C, Ferreira I, Borges JP.  2015.  One-pot synthesis of dual-stimuli responsive hybrid PNIPAAm-chitosan microgels. Materials & Design. 86:745-751. AbstractWebsite

The incorporation of magnetic nanoparticles into poly(N-isopropylacrylamide) (PNIPAAm) and chitosan microgels gives rise to hybrid systems that combine the microgels swelling capacity with the interesting features presented in magnetic nanoparticles. The presence of chitosan that act as surfactant for magnetic nanoparticles provides a simplistic approach which allows the encapsulation of magnetic nanoparticles without any previous surface modification. Spherical and highly monodisperse microgels with diameters in the range of 200 to 500 nm were obtained. The encapsulation of magnetic nanoparticles in the polymer matrix was confirmed by high resolution Scanning Electron Microscopy in transmission mode. Volume phase transition of the microgels was accessed by Dynamic Light Scattering measurements. It was observed that the thermosensitivity of the PNIPAM microgels still persists in the hybrid microgels; however, the swelling ability is compromised in the microgels with highest chitosan content. The heating performance of the hybrid magnetic microgels, when submitted to an alternating magnetic field, was also evaluated demonstrating the potential of these systems for hyperthermia treatments.

Echeverria, C, Soares P, Robalo A, Pereira L, Novo CMM, Ferreira I, Borges JP.  2015.  One-pot synthesis of dual-stimuli responsive hybrid PNIPAAm-chitosan microgels. Mater. Des. 86:745-751. AbstractWebsite

The incorporation of magnetic nanoparticles into poly(N-isopropylacrylamide) (PNIPAAm) and chitosan microgels gives rise to hybrid systems that combine the microgels swelling capacity with the interesting features presented in magnetic nanoparticles. The presence of chitosan that act as surfactant for magnetic nanoparticles provides a simplistic approach which allows the encapsulation of magnetic nanoparticles without any previous surface modification. Spherical and highly monodisperse microgels with diameters in the range of 200 to 500 nm were obtained. The encapsulation of magnetic nanoparticles in the polymer matrix was confirmed by high resolution Scanning Electron Microscopy in transmission mode. Volume phase transition of the microgels was accessed by Dynamic Light Scattering measurements. It was observed that the thermosensitivity of the PNIPAM microgels still persists in the hybrid microgels; however, the swelling ability is compromised in the microgels with highest chitosan content. The heating performance of the hybrid magnetic microgels, when submitted to an alternating magnetic field, was also evaluated demonstrating the potential of these systems for hyperthermia treatments.

Aquino, AS, Bernard FL, Borges JV, Mafra L, Dalla Vecchia F, Vieira MO, Ligabue R, Seferin M, Chaban VV, Cabrita EJ, Einloft S.  2015.  Rationalizing the role of the anion in CO2 capture and conversion using imidazolium-based ionic liquid modified mesoporous silica. RSC Advances. 5:64220-64227., Number {79}, {THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLAND}: {ROYAL SOC CHEMISTRY} Abstract

Covalently supported ionic liquids in mesoporous materials were prepared by grafting 1-methyl-3-(3-trimethoxysylilpropyl)imidazolium chloride in MCM-41. Subsequently, the {[}Cl-] anion was changed to {[}BF4-], {[}PF6-] or {[}Tf2N-]. These materials that present an advantageous combination of the properties of mesoporous solid materials and ionic liquids were evaluated for CO2 sorption as well as catalysts for CO2 conversion into cyclic carbonate using propylene oxide. The material with the {[}Cl-] anion had the best performance for both CO2 sorption and conversion. A CO2 sorption of 11 w/w% on the adsorbent was achieved and the cycloaddition reaction exhibited a conversion of 67% with 82% selectivity with the catalyst remaining active after 5 cycles, proving that the same sorbent/catalyst setup can be used for both CO2 capture and conversion. Based on the experimental data and electronic-structure numerical simulations, we have hypothesized two major reasons why chloride out performs other anions when adsorbed on MCM-41 unlike unsupported ionic liquids.

Carvalho, LCR, Ribeiro D, Seixas RSGR, Silva AMS, Nave M, Martins AC, Erhardt S, Fernandes E, Cabrita EJ, Marques MMB.  2015.  Synthesis and evaluation of new benzimidazole-based COX inhibitors: a naproxen-like interaction detected by STD-NMR. RSC Advances. 5:49098-49109., Number {61} Abstract

Non-steroidal anti-inflammatory drugs exert their pharmacological activity through inhibition of cyclooxygenase 1 and 2 (COX-1 and COX-2). Recent research suggests that a balanced inhibition of both COX-1 and COX-2 is the key to reduce the side-effects exhibited by COX inhibitors. We developed new benzimidazole-based compounds that showed a balanced COX inhibition, supported by molecular docking screening. The human whole blood assays demonstrated that the ester derivatives were potent inhibitors. Competitive saturation transfer difference (STD)-NMR experiments, in the presence of COX-2, using naproxen and diclofenac demonstrated that ester derivatives do not compete with diclofenac for the same binding site, but compete with the allosteric inhibitor naproxen. Combination of NMR spectroscopy with molecular docking has permitted us to detect a new naproxen-like inhibitor, which could be used for future drug development.

Soares, PIP, Lochte F, Echeverria C, Pereira L, Coutinho J, Ferreira I, Novo C, Borges JP.  2015.  Thermal and magnetic properties of iron oxide colloids: influence of surfactants. Nanotechnology. 26(42):425704. AbstractWebsite

Iron oxide nanoparticles (NPs) have been extensively studied in the last few decades for several biomedical applications such as magnetic resonance imaging, magnetic drug delivery and hyperthermia. Hyperthermia is a technique used for cancer treatment which consists in inducing a temperature of about 41–45 °C in cancerous cells through magnetic NPs and an external magnetic field. Chemical precipitation was used to produce iron oxide NPs 9 nm in size coated with oleic acid and trisodium citrate. The influence of both stabilizers on the heating ability and in vitro cytotoxicity of the produced iron oxide NPs was assessed. Physicochemical characterization of the samples confirmed that the used surfactants do not change the particles' average size and that the presence of the surfactants has a strong effect on both the magnetic properties and the heating ability. The heating ability of Fe3O4 NPs shows a proportional increase with the increase of iron concentration, although when coated with trisodium citrate or oleic acid the heating ability decreases. Cytotoxicity assays demonstrated that both pristine and trisodium citrate Fe3O4 samples do not reduce cell viability. However, oleic acid Fe3O4 strongly reduces cell viability, more drastically in the SaOs-2 cell line. The produced iron oxide NPs are suitable for cancer hyperthermia treatment and the use of a surfactant brings great advantages concerning the dispersion of NPs, also allowing better control of the hyperthermia temperature.

Soares, PIP, Lochte F, Echeverria C, Pereira LCJ, Coutinho JT, Ferreira IMM, Novo CMM, Borges JPMR.  2015.  Thermal and magnetic properties of iron oxide colloids: influence of surfactants. Nanotechnology. 26(42):425704. AbstractWebsite

Iron oxide nanoparticles (NPs) have been extensively studied in the last few decades for several biomedical applications such as magnetic resonance imaging, magnetic drug delivery and hyperthermia. Hyperthermia is a technique used for cancer treatment which consists in inducing a temperature of about 41–45 °C in cancerous cells through magnetic NPs and an external magnetic field. Chemical precipitation was used to produce iron oxide NPs 9 nm in size coated with oleic acid and trisodium citrate. The influence of both stabilizers on the heating ability and in vitro cytotoxicity of the produced iron oxide NPs was assessed. Physicochemical characterization of the samples confirmed that the used surfactants do not change the particles' average size and that the presence of the surfactants has a strong effect on both the magnetic properties and the heating ability. The heating ability of Fe3O4 NPs shows a proportional increase with the increase of iron concentration, although when coated with trisodium citrate or oleic acid the heating ability decreases. Cytotoxicity assays demonstrated that both pristine and trisodium citrate Fe3O4 samples do not reduce cell viability. However, oleic acid Fe3O4 strongly reduces cell viability, more drastically in the SaOs-2 cell line. The produced iron oxide NPs are suitable for cancer hyperthermia treatment and the use of a surfactant brings great advantages concerning the dispersion of NPs, also allowing better control of the hyperthermia temperature.

Kowacz, M, Marchel M, Juknaite L, Esperanca J, Romao MJ, Carvalho AL, Rebelo LPN.  2015.  Ionic-Liquid-Functionalized Mineral Particles for Protein Crystallization. Crystal Growth & Design. 15:2994-3003., Number 6 AbstractWebsite

Nucleation is a critical step determining the outcome of the entire crystallization process. Finding an effective nucleant for protein crystallization is of utmost importance for structural biology. The latter relies on good-quality crystals to solve the three-dimensional structures of macromolecules. In this study we show that crystalline barium sulfate (BaSO4) with an etched and/or ionic liquid (IL)-functionalized surface (1) can induce protein nucleation at concentrations well below the concentration needed to promote crystal growth under control conditions, (2) can shorten the nucleation time, (3) can increase the growth rate, and finally (4) may help to improve the protein crystal morphology. These effects were shown for lysozyme, RNase A, trypsin, proteinase K, myoglobin, and hemoglobin. Therefore, the use of BaSO4 particles enables us to reduce the amount of protein in crystallization trials and increases the chance of obtaining protein crystals of the desired quality. In the context of the underlying mechanism, it is shown that the protein-solid contact formation is governed by the interaction of the polar compartments of the biomacromolecule with the support. The tendency of a protein to concentrate near the solid surface is enhanced by both the hydrophobicity of the protein and that of the surface (tuned by the functionalizing IL). These mechanisms of interaction of biomacromolecules with inorganic hydrophilic solids correspond to the principles of amphiphilic IL-mineral interactions.

Corvo, M, Sardinha J, Casimiro T, Marin G, Seferin M, Einloft S, Menezes SC, Dupont J, Cabrita EJ.  2015.  A Rational Approach to CO2 Capture by Imidazolium Ionic Liquids: Tuning CO2 Solubility by Cation Alkyl Branching. ChemSusChem. 8:1935-46., Number 11 AbstractWebsite

Branching at the alkyl side chain of the imidazolium cation in ionic liquids (ILs) was evaluated towards its effect on carbon dioxide (CO2 ) solubilization at 10 and 80 bar (1 bar=1x10(5) Pa). By combining high-pressure NMR spectroscopy measurements with molecular dynamics simulations, a full description of the molecular interactions that take place in the IL-CO2 mixtures can be obtained. The introduction of a methyl group has a significant effect on CO2 solubility in comparison with linear or fluorinated analogues. The differences in CO2 solubility arise from differences in liquid organization caused by structural changes in the cation. ILs with branched cations have similar short-range cation-anion orientations as those in ILs with linear side chains, but present differences in the long-range order. The introduction of CO2 does not cause perturbations in the former and benefits from the differences in the latter. Branching at the cation results in sponge-like ILs with enhanced capabilities for CO2 capture.

Echeverria, C, Almeida PL, Feio G, Figueirinhas JL, Rey AD, Godinho MH.  2015.  Rheo-NMR study of water-based cellulose liquid crystal system at high shear rates. Polymer. 65:18-25. AbstractWebsite

Since long ago cellulosic lyotropic liquid crystals were thought as potential materials to produce fibers competitive with spidersilk or Kevlar, yet the processing of high modulus materials from cellulose-based precursors was hampered by their complex rheological behavior. In this work, by using the Rheo-NMR technique, which combines deuterium NMR with rheology, we investigate the high shear rate regimes that may be of interest to the industrial processing of these materials. Whereas the low shear rate regimes were already investigated by this technique in different works [1-4], the high shear rates range is still lacking a detailed study. This work focuses on the orientational order in the system both under shear and subsequent relaxation process arising after shear cessation through the analysis of deuterium spectra from the deuterated solvent water. At the analyzed shear rates the cholesteric order is suppressed and a flow-aligned nematic is observed which for the higher shear rates develops after certain time periodic perturbations that transiently annihilate the order in the system. During relaxation the flow aligned nematic starts losing order due to the onset of the cholesteric helices leading to a period of very low order where cholesteric helices with different orientations are forming from the aligned nematic, followed in the final stage by an increase in order at long relaxation times corresponding to the development of aligned cholesteric domains. This study sheds light on the complex rheological behavior of chiral nematic cellulose-based systems and opens ways to improve its processing. (C) 2015 Elsevier Ltd. All rights reserved.

2014
Simone, Zanarini, Garino, Nadia, Nair, JIJEESH RAVI, Francia, Carlotta, Wojcik PJ, Luis, Elvira, Rodrigo, Martins, Bodoardo, Silvia, Penazzi N.  2014.  Contrast Enhancement in Polymeric Electrochromic Devices Encompassing Room Temperature Ionic Liquids. International Journal of ELECTROCHEMICAL SCIENCE. 9:1650-1662.
Zubizarreta, C., Berasategui, E. G., Bayón, R., Escobar Galindo, R., Barros, R., Gaspar, Diana, Nunes, D., Calmeiro, T., Martins, Fortunato, Barriga J.  2014.  Evaluation of the optoelectronic properties and corrosion behavior of Al2O3-doped ZnO films prepared by dc pulsed magnetron sputtering. Journal of Physics D: Applied Physics. 47:13pp.
2013
C., C, M. R, C.M. S, J.J.G. M, E. O, E. J, M.G. A.  2013.  Nitrite biosensing using cytochrome c nitrite reductase: Towards a disposable strip electrode. Biomedical Engineering Systems and Technologies, Communications in Computer and Information Science. :41-51., DOI:10.1007/978-3-642-38256-7_3: Springer, Heidelberg
Parthiban, S., Elangovan, E., Nayak, Pradipta K., Gonçalves, G., Nunes, D., Pereira, Barquinha, Busani, Tito, Fortunato, Martins R.  2013.  Performances of Microcrystalline Zinc Tin Oxide Thin-Film Transistors Processed by Spray Pyrolysis. Journal of Display Technology, . 9(10):825-831.
Neves, CS, Granadeiro CM, Cunha-Silva L, Ananias D, Gago S, Feio G, Carvalho PA, Eaton P, Balula SS, Pereira E.  2013.  Europium Polyoxometalates Encapsulated in Silica Nanoparticles Characterization and Photoluminescence Studies. European Journal of Inorganic Chemistry. :2877-2886., Number 16 AbstractWebsite
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Neves, CS, Granadeiro CM, Cunha-Silva L, Ananias D, Gago S, Feio G, Carvalho PA, Eaton P, Balula SS, Pereira E.  2013.  Europium Polyoxometalates Encapsulated in Silica Nanoparticles Characterization and Photoluminescence Studies. European Journal of Inorganic Chemistry. :2877-2886., Number 16 AbstractWebsite

The incorporation of europium polyoxometalates into silica nanoparticles can lead to a biocompatible nanomaterial with luminescent properties suitable for applications in biosensors, biological probes, and imaging. Keggin-type europium polyoxometalates Eu(PW11)x (x = 1 and 2) with different europium coordination environments were prepared by using simple methodologies and no expensive reactants. These luminescent compounds were then encapsulated into silica nanoparticles for the first time through the water-in-oil microemulsion methodology with a nonionic surfactant. The europium polyoxometalates and the nanoparticles were characterized by using several techniques [FTIR, FT-Raman, 31P magic angle spinning (MAS) NMR, and TEM/energy-dispersive X-ray spectroscopy (TEM-EDS), AFM, dynamic light scattering (DLS), and inductively coupled plasma MS (ICP-MS) analysis]. The stability of the material and the integrity of the europium compounds incorporated were also examined. Furthermore, the photoluminescence properties of the Eu(PW11)x@SiO2 nanomaterials were evaluated and compared with those of the free europium polyoxometalates. The silica surface of the most stable nanoparticles was successfully functionalized with appropriate organosilanes to enable the covalent binding of oligonucleotides.

Corvo, M, Sardinha J, Menezes SC, Einloft S, Seferin M, Dupont J, Casimiro T, Cabrita EJ.  2013.  Solvation of carbon dioxide in [C4 mim][BF(4)] and [C(4) mim][PF(6)] ionic liquids revealed by high-pressure NMR spectroscopy. Angew Chem Int Ed Engl. 52:13024-7., Number 49 AbstractWebsite

Where is CO2 ? The intermolecular interactions of [C4 mim]BF4 and [C4 mim]PF6 ionic liquids and CO2 have been determined by high-pressure NMR spectroscopy in combination with molecular dynamic simulations. The anion and the cation are both engaged in interactions with CO2 . A detailed picture of CO2 solvation in these ILs is provided. CO2 solubility is essentially determined by the microscopic structure of the IL.

Corvo, MC, Sardinha J, Menezes SC, Einloft S, Seferin M, Dupont J, Casimiro T, Cabrita EJ.  2013.  Solvation of Carbon Dioxide in [C4mim][BF4] and [C4mim][PF6] Ionic Liquids Revealed by High-Pressure NMR Spectroscopy. Angewandte Chemie International Edition. 52:13024–13027., Number 49: WILEY-VCH Verlag Abstract
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Corvo, MC, Sardinha J, Menezes SC, Einloft S, Seferin M, Dupont J, Casimiro T, Cabrita EJ.  2013.  Solvation of CO2 in [C4mim][BF4] and [C4mim][PF6] ionic liquids revealed by High Pressure NMR. Angewandte Chemie International Edition. 49:13024-13027. AbstractWebsite
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2012
Sanz, V, Conde J, Ambrosone A, Hernandez Y, Marchesasno V, Estrada {GG }, Ibarra {MR }, Baptista {PV}, Tian F, Tortiglione C, {de la Fuente} {JM }.  2012.  Multifunctional gold nanoparticles for gene silencing, mar. Abstracts Of Papers Of The American Chemical Society. 243: ACS - American Chemical Society Abstract
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Gomes, I, Feio MJ, Santos NC, Eaton P, Serro AP, Saramago B, Pereira E, Franco R.  2012.  CONTROLLED ADSORPTION OF CYTOCHROME C TO NANOSTRUCTURED GOLD SURFACES. J. Nanopart. Res. . 14:1321.
Golshahi, S., Rozati, S.M., Botelho do Rego, A.M., Wang, J., Elangovan, E., Martins, Fortunato E.  2012.  Effect of substrate temperature on the properties of pyrolytically deposited nitrogen-doped zinc oxide thin films . Materials Science and Engineering: B. 178(1):103-108.
Elamurugu, E, Shanmugam P, Goncalves G, Franco N, Alves E, Martins R, Fortunato E.  2012.  The electronic transport mechanism in indium molybdenum oxide thin films RF sputtered at room temperature. Epl. 97(36002)
Parthiban, S., Gokulakrishnan, V., Elangovan, E., Gonçalves, G., Ramamurthi, K., Fortunato, Martins R.  2012.  High mobility and visible-near infrared transparent titanium doped indium oxide thin films produced by spray pyrolysis. Thin Solid Films. 524(1):268-271.
Santos, S, Marques V, Pires M, Silveira L, Oliveira H, Lanca V, Brito D, Madeira H, Esteves JF, Freitas A, Carreira IM, Gaspar IM, Monteiro C, Fernandes AR.  2012.  High resolution melting: improvements in the genetic diagnosis of hypertrophic cardiomyopathy in a Portuguese cohort. BMC Med Genet. 13:17.12santosbmcmg.pdf
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