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Ferreira, J, Santos T, Pereira P, Corvo MC, Queiroz JA, Sousa F, Cruz C.  2017.  Naphthalene amine support for G-quadruplex isolation. Analyst. 142(16):2982-2994.: Royal Society of Chemistry AbstractWebsite

G-quadruplex (G4) is involved in many biological processes, such as telomere function, gene expression and DNA replication. The selective isolation of G4 using affinity ligands that bind tightly and selectively is a valuable strategy for discovering new G4 binders for the separation of G4 from duplexes or the discrimination of G4 structures. In this work, one affinity chromatographic support was prepared using a naphthalene amine as a G4 binder. The ligand was immobilized on epoxy-activated Sepharose CL-6B using a long spacer arm and was characterized by HR-MAS spectroscopy. The supercoiled (sc) isoform of pVAX1-LacZ and pVAX1-G4 was isolated from a native sample. Also, the recovery and isolation of the plasmid isoforms from Escherichia coli lysate samples were achieved using an ionic gradient with different concentrations of NaCl in 10 mM Tris-HCl (pH 7.4). The retention times of different DNA/single strand sequences that can form G4, such as, c-MYC, c-kit1, c-kit2, tetrameric, telomeric (23AG), thrombin aptamer (TBA) and 58Sγ3 in this support were evaluated. Our experimental results suggest that the support exhibits selectivity for parallel c-MYC and c-kit1 G4s. In vitro transcription was performed using purified sc pVAX1-G4 and pPH600 to induce G4 formation and circular dichroism (CD) analysis confirmed that both transcripts adopt a parallel G4 topology.

Zanatta, M, Simon NM, Dupont J.  2020.  The Nature of Carbon Dioxide in Bare Ionic Liquid. ChemSusChem. 13:3101-3109. AbstractWebsite

Ionic liquids (ILs) are among the most studied and promising materials for selective CO2 capture and transformation. The high CO2 sorption capacity associated with the possibility to activate this rather stable molecule through stabilization of ionic/radical species or covalent interactions either with the cation or anion has opened new avenues for CO2 functionalization. However, recent reports have demonstrated that another simpler and plausible pathway is also involved in the sorption/activation of CO2 by ILs associated with basic anions. Bare ILs or IL solutions contain almost invariable significant amounts of water and through interaction with CO2 generate carbonates/bicarbonates rather than carbamic acids or amidates. In these cases, the IL acts as a base and not a nucleophile and yields buffer‐like solutions that can be used to shift the equilibrium toward acid products in different CO2 reutilization reactions. In this Minireview, the emergence of IL buffer‐like solutions as a new reactivity paradigm in CO2 capture and activation is described and analyzed critically, mainly through the evaluation of NMR data.

Martins, MB, Corvo ML, Marcelino P, Marinho HS, Feio G, Carvalho A.  2014.  New long circulating magnetoliposomes as contrast agents for detection of ischemia-reperfusion injuries by MRI. Nanomedicine. 10:207-14., Number 1 AbstractWebsite

New long circulating magnetoliposomes coated with polyethylene glycol (PEG), and loaded with PEG-coated 10nm superparamagnetic iron oxide nanoparticles (SPION), were developed. The magnetoliposomes relaxivities r1, r2 measured in a magnetic field of 7 T showed a minor effect on T1, but a major effect on T2. These nanosystems were used as a negative contrast agent for MRI in a nonclinical study to visualize, in a rat model of liver ischemia, ischemia-reperfusion injuries. Magnetic resonance micro-images (MRM) at 7 T were obtained for rat liver with and without magnetoliposomes administration and analyzed in comparison with liver biomarkers and histological results. These new long circulating magnetoliposomes enhanced the detection of lesions indicating their potential use as efficient MRI negative contrast agent for the detection of liver ischemia-reperfusion injuries. FROM THE CLINICAL EDITOR: This paper describes the generation of PEGylated magnetoliposomes and demonstrates their feasibility as negative contrast agents in a liver ischemia-reperfusion rat model.

Barrulas, RV, Paiva TG, Corvo M.  2019.  NMR Methodology for a Rational Selection of Ionic Liquids: Extracting Polyphenols. Separation and Purification Technology. : Elsevier AbstractWebsite

Extracts from plants have considerable significance as bioactive compounds with several pharmacological applications. Polyphenols have attracted the attention as anti-inflammatory and anti-oxidative materials. Nonetheless, the amount of these compounds in the extracts is typically very low. Consequently, green extraction techniques with higher efficiency for phenolic compounds are of paramount importance. Ionic liquids (ILs), which are also known as designer solvents can be used to extract polyphenols, however the search for ideal solvents is mostly done by trial and error. In this work, nuclear magnetic resonance (NMR) is used to study the profile of ILs molecular interactions with model compounds that mimic polyphenols. The ILs that exhibit the strongest molecular interactions were proven to have the highest efficiency when extracting polyphenols from matcha Japanese green tea, known to be extremely rich in these compounds. Both the IL cation and anion have an influence on the solvent behaviour. The best IL solvents for matcha polyphenols were imidazolium derivatives with shorter alkyl side chains and weakly basic anions such as tricyanomethanide, dicyanamide and triflate. Thus, the NMR approach avoids an exhaustive testing and allows the rational selection of the best ILs for the extraction.

Fundo, JF, Galvis-Sanchez A, Madureira AR, Carvalho A, Feio G, Silva CLM, Quintas MAC.  2016.  NMR water transverse relaxation time approach to understand storage stability of fresh-cut ‘Rocha’pear. LWT-Food Science and Technology. 74:280-285. AbstractWebsite

Fresh-cut fruit is an important segment in fruit market due to the increasing demand for healthy/convenient foods. However, processing promotes a decrease in fruits stability with faster physiological and microbiological deteriorations. Food stability is strongly attributed to its molecular dynamics and “water availability”. Understanding changes in water location/mobility is of utmost importance, since water dynamics profoundly influences physic-chemical and microbiological quality of foods. Nuclear magnetic resonance spectroscopy (NMR) is a methodology used to study the food constituents' molecular dynamics.

The aim of this study is to use NMR to evaluate changes in water mobility that occurred in fresh-cut pear tissues during storage, by measuring the transverse relaxation time (T2) parameter.

Results showed the existence of three water classes in the cells after processing, with T2 values of 10 ms, 187 ms and 3s for cellular wall, cytoplasm and vacuole, respectively. Also, the obtained results demonstrated that T2 was affected by processing and storage. Moreover, a relationship between T2, microstructure and the quality parameters was established. T2, maximum value increased with pear hardness as well as water activity. On the contrary, a decrease in total colour difference (TCD) was found with T2.

Results demonstrate the usefulness of the application of NMR relaxometry in food studies.

Nogueira, LS, Ribeiro S, Granadeiro CM, Pereira E, Feio G, Cunha-Silva L, Balula SS.  2014.  Novel polyoxometalate silica nano-sized spheres: efficient catalysts for olefin oxidation and the deep desulfurization process. Dalton Trans. 43:9518-28., Number 25 AbstractWebsite

A novel method to prepare silica nano-sized particles incorporating polyoxometalates was developed leading to a new efficient heterogeneous oxidative catalyst. Zinc-substituted polyoxotungstate [PW11Zn(H2O)O39](5-) (PW11Zn) was encapsulated into silica nanoparticles using a cross-linked organic-inorganic core, performed through successive spontaneous reactions in water. The potassium salt of PW11Zn and the composite formed, PW11Zn-APTES@SiO2, were characterized by a myriad of solid-state methods such as FT-IR, FT-Raman, (31)P and (13)C CP/MAS solid-state NMR, elemental analysis and SEM-EDS, confirming the integrity of the PW11Zn structure immobilized in the silica nanoparticles. The new composite has shown to be a versatile catalyst for the oxidation of olefins and also to catalyze the desulfurization of a model oil using H2O2 as the oxidant and acetonitrile as the solvent. The novel composite material was capable of being recycled without significant loss of activity and maintaining its structural stability for consecutive desulfurization and olefin oxidative cycles.

Granadeiro, CM, Ribeiro SO, Kaczmarek AM, Cunha-Silva L, Almeida PL, Gago S, Van Deun R, de Castro B, Balula SS.  2016.  A novel red emitting material based on polyoxometalate@ periodic mesoporous organosilica. Microporous and Mesoporous Materials. 234:248-256. AbstractWebsite

The first lanthanopolyoxometalate-supported bifunctional periodic mesoporous organosilica (BPMO) composite is here reported. The incorporation of decatunsgstoeuropate anions ([Eu(W5O18)2]9−) within the porous channels of an ethylene-bridged TMAPS-functionalized BPMO produced a luminescent material exhibiting a strong red emission under UV irradiation. Photoluminescence studies showed an efficient energy transfer process to the lanthanide emitting center in the material (antenna effect). A significant change in the coordination environment of Eu3+ ions was observed after its incorporation into the TMAPS-functionalized material. The possible reason for this is discussed within the paper.

Figueirinhas, JL, Feio G, Cruz C, Lehmann M, Kohn C, Dong RY.  2010.  Nuclear magnetic resonance spectroscopic investigations of phase biaxiality in the nematic glass of a shape-persistent V-shaped mesogen. J Chem Phys. 133:174509., Number 17 AbstractWebsite

Deuterium and carbon-13 NMR spectroscopy were used to study both the high temperature uniaxial nematic and the low temperature biaxial nematic glass of a shape-persistent V-shaped mesogen. It was found that biaxial ordering determined in the domains of the latter has symmetry lower than D(2h) and is compatible with C(2h) symmetry or lower. In particular, elements of the ordering matrix including biaxial phase order parameters were determined from (2)H NMR at two temperatures, one just below the glass transition, and the other deep inside the biaxial glass, which allowed for the characterization of the dominant molecular motions at these temperatures. (13)C NMR magic angle spinning sideband patterns, collected both in the high temperature nematic phase and in the nematic glass, clearly show the difference between them in terms of the phase symmetry.