Relaxivity and molecular dynamics of spin labeled polysaccharides

Site-selective and stochastic spin labelling of neutral water-soluble dietary fibers optimized for electron paramagnetic resonance spectroscopy

“…9B. This showed the same trend as in the previously published works (Gallez et al, 1994), and may be explained by somewhat larger mobility of the DF ends as compared to the middle parts of the DF chain. The values of the rotational correlation times of the nitroxide radical moieties were calculated using an empirical equation described in the method section.…”

“…To better understand the mechanism behind the interactions between polysaccharides and small nutritionally relevant molecules both at the molecular and macroscopic level, magnetic resonance technologies such as EPR (Electron Paramagnetic Resonance) and NMR (Nuclear Magnetic Resonance) can be applied, with available methodologies for both in vitro and in vivo studies. In particular, EPR spectra of polysaccharides can provide valuable information about the micro-environment of these biopolymers in solution as well as in the gel and solid states (Gallez et al, 1994;Gnewuch & Sosnovsky, 1986).…”

“…When it comes to neutral water-soluble DF, however, only a limited number of papers have been published so far. Gallez et al (1994) synthesised randomly spin labelled arabinogalactan via esterification with an unknown DS; Adma and Hall (1979) as well as Mawhinney et al (1983) synthesised multi-spin labelled guar gum via s-triazine alkylation and esterification, respectively, which yielded a very low DS of 0.5 % and 0.11 %, respectively, even with an excess of labelling reagent. Thus, both for reducing end spin labelling and for stochastic multi-spin-labelling of water-soluble neutral DFs, there is a demand for further improvement of the spin labelling efficiency to make DFs available for pulse EPR and paramagnetic NMR studies.…”

Electron paramagnetic resonance: a powerful tool to support magnetic resonance imaging research

“…Contrary to Gd‐based compounds, the main contribution is due to a distant interaction between the free electron and the water, and the contribution of the inner‐sphere process for hydrophilic nitroxide is considered to be negligible. There were several attempts to increase the relaxivity of nitroxides, namely by using the immobilization of nitroxides directly linked to macromolecules or strongly interacting with proteins such as albumin because of their large lipophilicity . EPR studies demonstrate that the degree of immobilization as evidenced by EPR spectrometry was directly correlated to an increased NMR r 1 relaxivity .…”

“…There were several attempts to increase the relaxivity of nitroxides, namely by using the immobilization of nitroxides directly linked to macromolecules or strongly interacting with proteins such as albumin because of their large lipophilicity . EPR studies demonstrate that the degree of immobilization as evidenced by EPR spectrometry was directly correlated to an increased NMR r 1 relaxivity . In addition, it was shown that the number of lipophilic nitroxides adsorbed on albumin (as quantified by EPR spectroscopy) was directly responsible for the increased relaxivity .…”