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The formation of host–guest complexes between surfactants and cyclodextrins
Valente, Artur J. M.; Söderman, OlleCyclodextrins are able to act as host molecules in supramolecular chemistry with applications ranging from pharmaceutics to detergency. Among guest molecules surfactants play an important role with both fundamental and practical applications. The formation of cyclodextrin/surfactant host–guest compounds leads to an increase in the critical micelle concentration and in the solubility of surfactants. The possibil...
Functional properties of sodium and calcium caseinate antimicrobial active film...
Arrieta, Marina P.; Peltzer, Mercedes A.; López, Juan; Garrigós, María del Carmen; Valente, Artur J. M.; Jiménez, AlfonsoActive edible films were prepared by adding carvacrol into sodium caseinate (SC) and calcium caseinate (CC) matrices plasticized with two different glycerol concentrations (25 and 35 wt%) prepared by solvent casting. Functional characterisation of these bio-films was carried out by determination of some of their physico-chemical properties, such as colour, transparency, oxygen barrier, wettability, dye permeati...
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...
Caracterização de acetato de celulose obtido a partir do bagaço de cana-de-açúc...
Cerqueira,Daniel A.; Rodrigues Filho,Guimes; Carvalho,Rui de A.; Valente,Artur J. M.A celulose do bagaço de cana-de-açúcar foi usada para sintetizar acetato de celulose com diferentes graus de substituição, os quais foram caracterizados por ¹H-RMN através da relação entre as áreas dos picos dos átomos de hidrogênio presentes nos grupos acetato (-(C=O)OCH3) e os picos dos hidrogênios ligados aos átomos de carbono dos anéis glicosídicos. A supressão de alguns sinais foi feita para remover sinais...
Interaction between Poly(9,9-bis(6′-N,N,N-trimethylammonium)hexyl)fluorene phen...
Monteserín, María; Burrows, Hugh D.; Valente, Artur J. M.; Mallavia, Ricardo; Paolo, Roberto E. Di; Maçanita, António L.; Tapia, María J.The interaction between three poly(9,9-bis(6-N,N,N-trimethylammonium)hexyl)fluorene phenylene) bromide (HTMA-PFP) samples of different molecular weights (Mn = 14.5, 30.1 and 61.3 kg/mol) and both dsDNA and ssDNA secondary structures has been studied using UV−visible absorption and fluorescence spectroscopies (including steady-state, time-resolved, and anisotropy measurements for the latter), viscosity, and elec...
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...
Aggregation and micellization of sodium dodecyl sulfate in the presence of Ce(I...
Valente, Artur J. M.; Burrows, Hugh D.; Cruz, Sandra M. A.; Pereira, Rui F. P.; Ribeiro, Ana C. F.; Lobo, Victor M. M.Aggregation properties of sodium dodecyl sulfate (SDS) in the presence of cerium(III) chloride, at various temperatures (298.15-323.15 K) have been measured by the electrical conductance technique. The experimental data on aqueous solutions as a function of SDS concentration show the presence of two inflexion points indicating the presence of two distinct interaction mechanisms: the first, occurring at SDS conc...
Mean distance of closest approach of ions: Lithium salts in aqueous solutions
Ribeiro, Ana C. F.; Lobo, Victor M. M.; Burrows, Hugh D.; Valente, Artur J. M.; Amado, Ana M.; Sobral, Abílio J. F. N.; Teles, Ana S. N.Numerical values for the mean distance of closest approach of ions, "a", for lithium salts in aqueous solutions are presented and discussed. These values were obtained from both experimental activity and diffusion coefficients, and estimated by using different theoretical approaches. ; http://www.sciencedirect.com/science/article/B6TGR-4RR1NKM-1/1/b8d3cdac33991c5424d567940bc0c3a6
Diffusion coefficients and electrical conductivities for calcium chloride aqueo...
Ribeiro, Ana C. F.; Barros, Marisa C. F.; Teles, Ana S. N.; Valente, Artur J. M.; Lobo, Victor M. M.; Sobral, Abílio J. F. N.; Esteso, M. A.http://www.sciencedirect.com/science/article/B6TG0-4T7XGV2-6/2/9f2789c31efbabbadc8d9358c079cafe
Interaction between DNA and Cationic Surfactants: Effect of DNA Conformation an...
Dias, Rita S.; Magno, Luís M.; Valente, Artur J. M.; Das, Dibyendu; Das, Prasanta K.; Maiti, Souvik; Miguel, Maria G.; Lindman, BjörnThe interactions between DNA and a number of different cationic surfactants, differing in headgroup polarity, were investigated by electric conductivity measurements and fluorescence microscopy. It was observed that, the critical association concentration (cac), characterizing the onset of surfactant binding to DNA, does not vary significantly with the architecture of the headgroup. However, comparing with the ...
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