Biomembrane elastometry using fast-field-cycling NMR

CARLA FRAENZA; GABRIELA A. DOMINGUEZ; ESTEBAN ANOARDO

Conferencia; 9th Conference on Fast Field-Cycling NMR Relaxometry; 2015

The study of the lipid dynamics in liposomemembranes using proton NMR field-cycling relaxometry revealed that the smectic collectivenature of the dynamics should be considered for a consistent interpretation ofthe measured relaxation disperssions1-3. An interesting feature isthat the collective dynamics is particularly sensitive to the bending elasticmodulus of the membrane. It was found that the sensitivity of the relaxationdispersion to the elastic modulus is maximal within a restricted frequencyrange4, where the collective dynamics represent the dominantdispersive contribution. A direct consequence of this fact is that the physicalmodel can be simplified within this interval, turning to be more robust for theextraction of the bending modulus from the dispersion. The proton spin-latticerelaxation rate (R1) was measured in typical samples within therestricted Larmor frequency range (typically 200kHz to 2MHz) using twodifferent field-cycling machines: a new Stelar Spinmaster FFC2000 1T C/DC relaxometerand an older version equipped with a degraded magnet homogeneity (lower than350ppm/cm3). The obtained parameters were compared with thoseextracted from the relaxation dispersions measured in an extended frequencyrange. The sensitivity of the dispersions to the magnet homogeneity was analyzed.    [1]- C. Meledandri; J. Perlo; E. Farrher; D.Brougham; E. Anoardo. J. Chem. Phys. B 2009,113, 15532.[2]- J. Perlo; C. Meledandri; E. Anoardo;  D. Brougham. J. Chem. Phys. B 2011,115, 3444.[3]- C. Fraenza; C.Meledandri; E. Anoardo; D. Brougham. ChemPhysChem 2014, 15, 425.[3]- Josefina Perlo, PhD.Thesis. 2011. UniversidadNacional de Córdoba, Argentina.