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Flexographic Printed Flexible Thermochromic Stickers for Smart Sensing Applications
Publication . Morais, M.; Figueira, J.; Corvo, M. C.; Peixoto, M.; Oliveira, D.; Gonçalves, A.; Fortunato, E.; Martins, R.; Carlos, E.; Pinto, J. V.; DCM - Departamento de Ciência dos Materiais; CENIMAT-i3N - Centro de Investigação de Materiais (Lab. Associado I3N); John Wiley and Sons Ltd
The growing demand for thermochromic materials in areas such as food packaging requires the development of fast-response and extended-life materials. The use of metal cation-ionic liquid complexes is increasing due to the easiness to tailor their properties, leading to changes in thermochromic response. This work presents the synthesis and introduction of thermochromic 1-butyl-3-methylimidazolium chloride and 4-chloronickelate ([BMIm]2[NiCl4]) complexes into water-based inks. Formulations with varying concentrations of complexes (10–40 wt.%) are printed on tags thorugh a roll-to-roll process and tested between 30–45 °C. Also, films with one to five layers are analyzed for color contrast and different encapsulating materials are studied to improve the thermochromic films' robustness. The optimal films, with three layers of ink with 40 wt.% complexes encapsulated with Fixomull Transparent present enhanced color contrast and fast response time. Red-green-blue analysis is performed on these films, revealing a blue/red ratio of 1.7 after heating at 40 °C for 30 min. This work paves the way for developing flexible stickers with fast response and high contrast. The innovative and straightforward thermochromic inks' production process and compatibility with large-scale manufacturing show their promising future as cost-effective stickers for smart packaging applications, such as visual indicators of ideal food consumption temperatures.
Comparing the Chemistry of Malvidin-3-O-glucoside and Malvidin-3,5-O-diglucoside Networks
Publication . Seco, André; Pereira, Ana Rita; Camuenho, Ambrósio; Oliveira, Joana; Dias, Ricardo; Brás, Natércia F.; Basílio, Nuno; Parola, A. Jorge; Lima, João C.; de Freitas, Victor; Pina, Fernando; LAQV@REQUIMTE; DQ - Departamento de Química; ACS - American Chemical Society
The kinetics, thermodynamics, and degradation of malvidin mono- and diglucosides were studied following a holistic approach by extending to the basic medium. In acidic conditions, the reversible kinetics of the flavylium cation toward the equilibrium is controlled by the hydration and cis-trans isomerization steps, while in the basic medium, the OH- nucleophilic addition to the anionic quinoidal bases is the slowest step. There is a pH range (transition pHs), between the acidic and basic paradigms, that includes physiological pH (7.4), where degradation reactions occur faster, preventing the system from reaching the equilibrium. The transition pH of the diglucoside is narrower, and in contrast with the monoglucoside, there is no evidence for the formation of colored oligomers among the degradation products. Noteworthy, OH- addition in position 4 to form B42-, a kinetic product that decreases the overall equilibration rate, was observed only for the diglucoside.
Unraveling Molecular Recognition of Glycan Ligands by Siglec-9 via NMR Spectroscopy and Molecular Dynamics Modeling
Publication . Atxabal, Unai; Nycholat, Corwin; Pröpster, Johannes M.; Fernández , Andrea; Oyenarte, Iker; Lenza, Maria Pia; Franconetti, Antonio; Soares, Cátia O.; Coelho, Helena; Marcelo, Filipa; Schubert, Mario; Paulson, James C.; Jiménez-Barbero, Jesús; Ereño-Orbea, June; DQ - Departamento de Química; UCIBIO - Applied Molecular Biosciences Unit; ACS - American Chemical Society
Human sialic-acid-binding immunoglobulin-like lectin-9 (Siglec-9) is a glycoimmune checkpoint receptor expressed on several immune cells. Binding of Siglec-9 to sialic acid containing glycans (sialoglycans) is well documented to modulate its functions as an inhibitory receptor. Here, we first assigned the amino acid backbone of the Siglec-9 V-set domain (Siglec-9d1), using well-established triple resonance three-dimensional nuclear magnetic resonance (NMR) methods. Then, we combined solution NMR and molecular dynamic simulation methods to decipher the molecular details of the interaction of Siglec-9 with the natural ligands α2,3 and α2,6 sialyl lactosamines (SLN), sialyl Lewis X (sLeX), and 6-O sulfated sLeX and with two synthetically modified sialoglycans that bind with high affinity. As expected, Neu5Ac is accommodated between the F and G β-strands at the canonical sialic acid binding site. Addition of a heteroaromatic scaffold 9N-5-(2-methylthiazol-4-yl)thiophene sulfonamide (MTTS) at the C9 position of Neu5Ac generates new interactions with the hydrophobic residues located at the G-G′ loop and the N-terminal region of Siglec-9. Similarly, the addition of the aromatic substituent (5-N-(1-benzhydryl-1H-1,2,3-triazol-4-yl)methyl (BTC)) at the C5 position of Neu5Ac stabilizes the conformation of the long and flexible B′-C loop present in Siglec-9. These results expose the underlying mechanism responsible for the enhanced affinity and specificity for Siglec-9 for these two modified sialoglycans and sheds light on the rational design of the next generation of modified sialoglycans targeting Siglec-9.
Poly(ionic liquid)-based aerogels for continuous-flow CO2 upcycling
Publication . Barrulas, Raquel V.; Tinajero, Cristopher; Ferreira, Diogo P. N.; Illanes-Bordomás, Carlos; Sans, Victor; Carrott, Manuela Ribeiro; García-González, Carlos A.; Zanatta, Marcileia; Corvo, Marta C.; CENIMAT-i3N - Centro de Investigação de Materiais (Lab. Associado I3N); DCM - Departamento de Ciência dos Materiais; Elsevier BV
The atmospheric concentration of CO2 is rising at an alarming pace, creating a pressing need for new and sustainable materials capable of capture and conversion. Poly(ionic liquid)s (PILs) are particularly effective catalysts for processes at or near atmospheric pressure. PILs industrial application poses challenges due to the low porosity of PIL, the limited batch conversion capacity, and the difficulties in reuse. To overcome these limitations, we herein propose the use of AEROPILs catalysts obtained from the integration of PILs in chitosan-based aerogels. These cost-effective highly porous materials have unique and tuneable porous properties making them not only ideal sustainable CO2 sorbents but also promising heterogeneous catalysts. While AEROPILs show moderate yields for CO2 conversion in batch mode, high catalytic activity was achieved when AEROPILs were used to catalyse the CO2 cycloaddition reaction to epoxides in packed-bed reactors operated under continuous flow. The catalytic activity and stability were maintained over 60 h without activity loss, and high productivity (space-time yield of 21.18 gprod h−1 L−1). This research reveals the pioneering use of AEROPILs to efficiently upcycle CO2 into cyclic carbonate under a continuous flow setup.
New insights in uranium bioremediation by cytochromes of the bacterium Geotalea uraniireducens
Publication . Almeida, Alexandre; Turner, David L.; Silva, Marta A.; Salgueiro, Carlos A.; Instituto de Tecnologia Química e Biológica António Xavier (ITQB); UCIBIO - Applied Molecular Biosciences Unit; DQ - Departamento de Química; Faculdade de Ciências e Tecnologia (FCT); ASBMB - American Society for Biochemistry and Molecular Biology
The bacterium Geotalea uraniireducens, commonly found in uranium-contaminated environments, plays a key role in bioremediation strategies by converting the soluble hexavalent form of uranium (U(VI)) into less soluble forms (e.g., U(IV)). While most of the reduction and concomitant precipitation of uranium occur outside the cells, there have been reports of important reduction processes taking place in the periplasm. In any case, the triheme periplasmic cytochromes are key players, either by ensuring an effective interface between the cell's interior and exterior or by directly participating in the reduction of the metal. Therefore, understanding the functional mechanism of the highly abundant triheme cytochromes in G. uraniireducens’ is crucial for elucidating the respiratory pathways in this bacterium. In this work, a detailed functional characterization of the triheme cytochromes PpcA and PpcB from G. uraniireducens was conducted using NMR and visible spectroscopy techniques. Despite sharing high amino acid sequence identity and structural homology with their counterparts from Geobacter sulfurreducens, the results showed that the heme reduction potential values are less negative, the order of oxidation of the hemes is distinct, and the redox and redox-Bohr network of interactions revealed unprecedented functional mechanisms in the cytochromes of G. uraniireducens. In these cytochromes, the reduction potential values of the three heme groups are much more similar, resulting in a narrower range of values, that facilitates directional electron flow from the inner membrane, thereby optimizing the uranium reduction.
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Fundação para a Ciência e a Tecnologia
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Concurso para Financiamento de Projetos de Infraestruturas de Investigação inseridas no Roteiro Nacional de Infraestruturas de Investigação de Interesse Estratégico
Número da atribuição
PINFRA/22161/2016