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Plasmid DNA hydrogels for biomedical applications
Costa, Diana; Valente, Artur J. M.; Miguel, M. Graça; Queiroz, JoãoIn the last few years, our research group has focused on the design and development of plasmid DNA (pDNA) based systems as devices to be used therapeutically in the biomedical field. Biocompatible macro and micro plasmid DNA gels were prepared by a cross-linking reaction. For the first time, the pDNA gels have been investigated with respect to their swelling in aqueous solution containing different additives. F...
Antioxidant activity of six Portuguese thyme species essential oils
Dandlen, S. Anahi; Lima, A. Sofia; Mendes, Marta D.; Miguel, M. Graça; Faleiro, M. Leonor; Sousa, Maria João; Pedro, Luís G.; Barroso, J.G.The essential oils of Thymus caespititius, T. camphoratus, T. capitellatus, T. carnosus, T. pulegioides, T. zygis subsp. zygis and T. zygis subsp. sylvestris collected in diff erent regions of Portugal, including the Azores islands, were evaluated for preventing lipid peroxidation and scavenging free radicals, and hydroxyl and superoxide anions. T. zygis subsp. zygis oil possessed the best capacity for preventi...
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...
Effect of Additives on Swelling of Covalent DNA Gels
Costa, Diana; Miguel, M. Graça; Lindman, BjörnThe volumetric response of polymer gels on cosolute addition depends on the interaction of the polymer with the cosolute and can be used as a simple and sensitive way of elucidating these interactions. Here we report on DNA networks, prepared by crosslinking double-stranded DNA with ethylene glycol diglycidyl ether (EGDE); these have been investigated with respect to their swelling in aqueous solution containin...
Surfactant−DNA Gel Particles: Formation and Release Characteristics
Morán, M. Carmen; 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 here to form DNA gel particles by interfacial diffusion. We report on the formation of DNA gel particles by mixing solutions of DNA (either single-stranded (ssDNA) or double-stranded (dsDNA)) with solutions of cationic surfactant ...
DNA Gel Particles: Particle Preparation and Release Characteristics
Morán, M. Carmen; 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 here to form DNA gel particles by interfacial diffusion. We report the formation of DNA gel particles by mixing solutions of DNA (either single-stranded (ssDNA) or double-stranded (dsDNA)) with solutions of cationic surfactant CTA...
Interaction between Covalent DNA Gels and a Cationic Surfactant
Costa, Diana; Hansson, Per; Schneider, Stefanie; Miguel, M. Graça; Lindman, BjörnThe interaction of covalently cross-linked double-stranded (ds) DNA gels and cetyltrimethylammonium bromide (CTAB) is investigated. The volume transition of the gels that follows the absorption of the oppositely charged surfactant from aqueous solution is studied. As do other polyelectrolyte networks, DNA networks form complexes with oppositely charged surfactant micelles at surfactant concentrations far below ...
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