@article {17483, title = {Paramagnetic NMR Relaxation in Polymeric Matrixes: Sensitivity Enhancement and Selective Suppression of Embedded Species (1H and 13C PSR Filter)}, journal = {Journal of the American Chemical Society}, year = {2009}, month = {2009-11-16 00:00:00}, pages = {15164}, abstract = {

A study of the practical applications of the addition of paramagnetic spin relaxation (PSR) ions to a variety of polymers (PLL, PAA, PGA, PVP, and polysaccharides such as hyaluronic acid, chitosan, mannan, and dextran) in solution (D2O and DMSO-d6) is described. Use of GdIII, CuII, and MnII\ allows a reduction of up to 500\% in the\ 1H longitudinal relaxation times (T1), and so in the time necessary for recording quantitative NMR spectra (sensitivity enhancement) neither an increase of the spectral line width nor chemical shift changes resulted from addition of any of the PSR agents tested. Selective suppression of the\ 1H and13C NMR signals of certain components (low MW molecules and polymers) in the spectrum of a mixture was attained thanks to their different sensitivity [transverse relaxation times (T2)] to GdIII\ (PSR filter). Illustration of this strategy with block copolymers (PGA-g-PEG) and mixtures of polymers and low MW molecules (i.e., lactose-hyaluronic acid, dextran-PAA, PVP-glutamic acid) in 1D and 2D NMR experiments (COSY and HMQC) is presented. In those mixtures where PSR and CPMG filters alone failed in the suppression of certain components (i.e., PVP-mannan-hyaluronic acid) due to their similarity of\ 1H\ T2\ values and sensitivities to GdIII, use of the PSR filter in combination with CPMG sequences (PSR-CPMG filter) successfully resulted in the sequential suppression of the components (hyaluronic acid first and then mannan)

}, keywords = {NMR, Paramagnetic; Chitosan}, author = {Fernandez-Megia, E. and Correa, J. and Novoa-Carballal, R. and Riguera, R.} }