Encontrados 13 documentos, a visualizar página 1 de 2
Is axenicity crucial to cryopreserve microalgae?
Amaral, Raquel; Pereira, Jorge C.; Pais, Alberto A. C. C.; Santos, Lília M. A.Large culture collections of microalgae and cyanobacteria such as the Coimbra Collection of Algae (ACOI) hold unialgal cultures consisting of a population of cells/colonies of a certain species. These cultures are usually non-axenic, as other organisms such as bacteria and microfungi are also present in culture due to co-isolation. Attention has been recently given to partner organisms since studies indicate th...
Solubilization of Poly1,4-phenylene-[9,9-bis(4-phenoxy-butylsulfonate)] fluoren...
Burrows, Hugh D.; Tapia, María J.; Fonseca, Sofia M.; Pradhan, Swapna; Scherf, Ullrich; Silva, Cláudia L.; Pais, Alberto A. C. C.; Valente, Artur J. M.In the presence of the nonionic alkyloxyethylene surfactant n-dodecylpentaoxyethylene glycol ether (C12E5), the anionic conjugated polyelectrolyte (CPE) poly1,4-phenylene-[9,9-bis(4-phenoxy-butylsulfonate)]fluorene-2,7-diyl (PBS-PFP) dissolves in water, leading to a blue shift in fluorescence and dramatic increases in fluorescence quantum yields above the surfactant critical micelle concentration (cmc). No sign...
Controlling the Morphology in DNA Condensation and Precipitation
Pinto, Maria F. V.; Morán, M. Carmen; Miguel, M. Graça; Lindman, Björn; Jurado, Amália S.; Pais, Alberto A. C. C.This work addresses the influence of solution inhomogeneity on conformation, aggregation, and coil/globule and bundle/single chain coexistence of T4 DNA molecules. The inhomogeneity is induced by mixing two solutions containing, respectively, protamine and DNA, with different relative concentrations, but aiming at producing the same final concentrations. The study was conducted by means of fluorescence microsco...
Mixed Protein Carriers for Modulating DNA Release
Morán, M. Carmen; Pais, Alberto A. C. C.; Ramalho, Amilcar; Miguel, M. Graça; Lindman, BjörnAqueous mixtures of oppositely charged polyelectrolytes undergo associative phase separation, resulting in coacervation, gelation, or precipitation. This phenomenon has been exploited in forming DNA gel particles by interfacial diffusion. We report here the formation of DNA gel particles by mixing solutions of double-stranded DNA with aqueous solutions containing two cationic proteins, lysozyme and protamine su...
Cationic agents for DNA compaction
Gaweda, Sylwia; Morán, M. Carmen; Pais, Alberto A. C. C.; Dias, Rita S.; Schillén, Karin; Lindman, Björn; Miguel, M. GraçaFluorescence microscopy was used to investigate the conformational changes of individual T4 DNA molecules induced by different compacting agents, namely the cationic surfactants, cetyltrimethylammonium bromide (CTAB) and chloride (CTAC), iron(III), lysozyme, and protamine sulfate. A protocol for establishing size estimates is suggested to obtain reproducible results. Observations show that in the presence of ly...
Use of an acoustic wave sensor to follow lead absorption by porcine skin
Veríssimo, Marta I. S.; Pais, Alberto A. C. C.; Oliveira, João A. B. P.; Gomes, M. Teresa S. R.A new acoustic wave sensor capable of detecting and quantifying lead is presented, and fully characterized in terms of sensitivity, selectivity, and linear calibration range. The sensor was used to quantify lead absorption by pig stratum corneum and to follow in real time, both the absorption and desorption of lead by the skin. Values of lead absorption of 29.6 mg Pb2+/g of stratum corneum were obtained. Lead i...
Aggregation and gelation in hydroxypropylmethyl cellulose aqueous solutions
Silva, Sérgio M. C.; Pinto, Fátima V.; Antunes, Filipe E.; Miguel, Maria G.; Sousa, João J. S.; Pais, Alberto A. C. C.http://www.sciencedirect.com/science/article/B6WHR-4TC923M-1/2/012a59092ead1ce270813efcf98c1fb2
Films based on chitosan polyelectrolyte complexes for skin drug delivery: Devel...
Silva, Cláudia L.; Pereira, Jorge C.; Ramalho, Amílcar; Pais, Alberto A. C. C.; Sousa, João J. S.Novel chitosan based polyelectrolyte complexes (PEC) were developed and optimized in order to obtain films possessing the optimal functional properties (flexibility, resistance, water vapour transmission rate and bioadhesion) to be applied on skin. The development was based on the combination of chitosan and two polyacrylic acid (PAA) polymers with different crosslinkers and crosslinking densities. The interact...
Interplay of Electrostatic and Hydrophobic Effects with Binding of Cationic Gem...
Burrows, Hugh D.; Tapia, María J.; Silva, Cláudia L.; Pais, Alberto A. C. C.; Fonseca, Sofia M.; Pina, João; Melo, J. Seixas de; Wang, YujieUnderstanding factors responsible for the fluorescence behavior of conjugated polyelectrolytes and modulation of their behavior are important for their application as functional materials. The interaction between the anionic poly1,4-phenylene-[9,9-bis(4-phenoxy-butylsulfonate)]fluorene-2,7-diylcopolymer (PBS−PFP) and cationic gemini surfactants α,ω-(CmH2m+1N+(CH3)2)2(CH2)s(Br-)2 (m-s-m; m = 12, s = 2, 3, 5, 6, ...
1,3-Dipolar cycloaddition of azomethine ylides generated from aziridines in sup...
Gomes, Paulo J. S.; Nunes, Cláudio M.; Pais, Alberto A. C. C.; Melo, Teresa M. V. D. Pinho e; Arnaut, Luis G.The 1,3-dipolar cycloaddition of azomethine ylides with DMAD in supercritical carbon dioxide is reported. The photolysis reaction conditions were optimized with a suitable adjustment of pressure, temperature, irradiation time and co-solvent concentration leading to a more efficient reaction than in neat acetonitrile. Similar results were observed using thermal reaction conditions. Supercritical carbon dioxide w...
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