Characterization of molecular dynamics and elastic proper- ties of flexible liposomes using Fast Field-Cycling NMR

MARÍA BELÉN MARZOLA CORONEL; CARLA CECILIA FRAENZA; ESTEBAN ANOARDO

CABA

Conferencia; IV Workshop on Magnetic Resonance; 2018

At present, the development of nanometric vesicles for drug delivery in the human bodyby different routes has become of great interest for the pharmaceutical industry. Flexibleliposomes have proved to be useful for transdermal transport, therefore it is important tomeasure the bending elastic modulus k of the membrane. This constant has an inverseproportionality relation with the parameter called deformability or adaptability of the vesicles,being one of the most relevant parameters related to the penetration dynamics in the skin.In previous works [1-5], a model was presented to interpret the spin-lattice relaxation ratedispersion of protons, obtained with the fast field cycling nuclear magnetic relaxometrytechnique (FFC), for unilamellar liposomes. In addition to providing general information on thelipid dynamics, this model allows us to infer about the elastic properties of the liposomes bymeans of the elastic constant k, which is one of the physical parameters involved in the model.This model has been validated from measurements of k for cholesterol doped vesicles in orderto increase the value of the constant. On the other hand, in order to extend it in the oppositelimit of membrane flexibility, experiments using elastic vesicles were performed in this work.Specifically, we analyzed experimental relaxation dispersions obtained at different temperatures(291-328K) for liposomes of radius of 50nm, composed of SPC (soy phosphatidylcholine) withdifferent ionic (sodium deoxycholate and Span 80) and nonionic (Tween 80 and BrijO20)detergents added to enhance the membrane flexibility, at concentrations up to 40 mol%.The model was successfully extended for this type of liposomes. Slight variations in kwere obtained (around 10%) in response to the additive concentration greater than 20mol%. Itwas also noted that the dynamics of the lipids in the elastic liposomes did not depend on themolecular mass or ionicity of the detergent.References:1. Meledandri, C. J.; Perlo, J.; Farrher, E; Brougham, D.F.; Anoardo, E. J. Phys. Chem. B. 2009,15532, 113.2. Perlo, J.; Meledandri, C. J.; Anoardo, E.; Brougham, D.F. J. Phys. Chem. B. 2011, 3444, 115.3. Fraenza, C. C.; Meledandri, C. J.; Anoardo, E.; Brougham, D. F. ChemPhysChem. 2014, 425,15.4. Domingez, G. A.; Perlo, J.; Fraenza, C. C.; Anoardo, E. Chem. Phys. Lipids. 2016, 21, 201.5. Fraenza, C. C.; Anoardo, E. Biophysical Chemistry. 2017, 38, 228.