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WATER AND CARBOHYDRATES: MACROSCOPIC AND MOLECULAR ASPECTS OF THEIR INTERACTIONS

Grant number: 08/00908-4
Support type:Scholarships in Brazil - Doctorate
Effective date (Start): August 01, 2008
Effective date (End): February 29, 2012
Field of knowledge:Physical Sciences and Mathematics - Chemistry - Physical-Chemistry
Principal researcher:Edvaldo Sabadini
Grantee:Marcus Vinícius Cangussu Cardoso
Home Institution: Instituto de Química (IQ). Universidade Estadual de Campinas (UNICAMP). Campinas , SP, Brazil

Abstract

Carbohydrate aqueous solutions comprise systems of great importance in broad and general terms, from industrial applications to the more elaborated mechanisms taking place in the cells. Aqueous solutions of mono, di, and oligosaccharides were studied at macroscopic and molecular standpoints by undertaking thermodynamic and spectroscopic experiments. The effect of hydrogen-bonding strength on the solubility of a series of mono, di and oligosaccharides showed to be strongly dependent of the solubility of the carbohydrate in H2O. As lower is the solubility of the carbohydrate, greater will be the deuterium isotopic effect on its solubility caused by the replacement of H2O for D2O. These results suggest that low-soluble carbohydrates perturb more strongly the water structure. Owing to the cooperativity of the coil-helix transition, the deuterium isotopic effect on the gelling of k-carrageenan, is intensified leading to stronger gels and helical states more stable in D2O. On the molecular perspective, based on spin-spin nuclear magnetic relaxation, the proton exchange rates, k_b, between water and OH-carbohydrate, are dependent of the nature of the saccharide. The value is higher for linear than for pyranoside, and the slowest value is found for fructofuranoside form. The magnetization transferring between proton pools of water and CH-carbohydrates are modulated by proton molecular motions and by the exchanging process between water and OH-carbohydrate protons. 1H NMR relaxation experiments of exchangeable protons provide to be rich to probe the micelar aggregation of n-alkyl-glycosides. It was possible to demonstrate experimentally that the aggregation of the surfactants molecules provokes a drastic reduction on the water and saccharide heads interactions.

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Scientific publications
(References retrieved automatically from Web of Science and SciELO through information on FAPESP grants and their corresponding numbers as mentioned in the publications by the authors)
CARDOSO, MARCUS V. C.; SABADINI, EDVALDO. Before and Beyond the Micellization of n-Alkyl Glycosides. A Water-H-1 NMR Relaxation Study. Langmuir, v. 29, n. 51, p. 15778-15786, . (08/00908-4)
CARDOSO, MARCUS V. C.; CARVALHO, LARISSA V. C.; SABADINI, EDVALDO. Solubility of carbohydrates in heavy water. Carbohydrate Research, v. 353, p. 57-61, . (08/00908-4)
Academic Publications
(References retrieved automatically from State of São Paulo Research Institutions)
CARDOSO, Marcus Vinícius Cangussu. Water and carbohydrates: macroscopic and molecular aspects of their interactions. 2012. Doctoral Thesis - Universidade Estadual de Campinas (UNICAMP). Instituto de Química Campinas, SP.

Please report errors in scientific publications list by writing to: cdi@fapesp.br.