کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
5403169 1392753 2007 8 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Europium ion as a probe for binding sites to carrageenans
موضوعات مرتبط
مهندسی و علوم پایه شیمی شیمی تئوریک و عملی
پیش نمایش صفحه اول مقاله
Europium ion as a probe for binding sites to carrageenans
چکیده انگلیسی
Carrageenans, sulfated polysaccharides extracted from red algae, present a coil-helix transition and helix aggregation dependence on the type and concentration of counterions. In this study, we focus attention on a mixed valence counterion system: Eu3+/Na+ or K+ with different gel-forming carrageenans: kappa, iota, and kappa-2. Results of stationary and time-dependent luminescence showed to be a suitable tool to probe ion binding to both the negatively charged sulfate group and the hydroxyl groups present in the biopolymer. For lower europium ion concentrations, a single longer decay emission lifetime was detected, which was attributed to the binding of europium ion to the carrageenan sulfate groups. An additional decay ascribed to europium binding to hydroxyl groups was observed above a threshold concentration, and this decay was dependent on the carrageenan charge density. Symmetry of the europium ion microenvironment was estimated by the ratio between the intensities of its emission bands, which has been shown to depend on the concentration of europium ions and on the specificity of the monovalent counterion bound to the carrageenan.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of Luminescence - Volume 127, Issue 2, December 2007, Pages 461-468
نویسندگان
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