PFG‐NMR Investigation of Liposome Systems Containing Hydrotrope

Abstract

Particle size is crucially important in determining the usefulness of a liposome system. This is particularly true for drug delivery applications. Until now, the particle size of a liposome is typically determined using a light scattering method. Although NMR pulsed field gradient (PFG) experiments are known to yield self‐diffusion coefficients for micelles and other particulate matters, the application of this technique to vesicle systems has been limited due to the rigid nature of the lipid bilayer, which usually does not give well‐defined NMR signals for PFG experiments. This study shows that the polyethylene oxide chains on a pegylated lipid could serve as an excellent tracer to measure the self‐diffusion coefficient via PFG method. In addition, liposomes containing a hydrotrope also give adequate signal from the lipid for PFG experiments due to the increased flexibility of the lipid molecules. In addition to particle size, PFG‐NMR is also used to determine the extent of association of a hydrotrope with the liposome bilayer.

Keywords:

• Pulse field gradient NMR
• polymer-stabilized liposomes
• sodium xylene sulfonate
• particle size
• dynamic light scattering