Oligonucleotide and Water Self-Diffusion in Systems of Pluronic Triblock Copolymers and in Buffer Solutions by Pulsed Field Gradient Nuclear Magnetic Resonance

Abstract

Pulsed field gradient nuclear magnetic resonance (PFGNMR) measurements of oligonucleotide (poly-thymidine, T1 to T30) self-diffusion coefficients in gels of Pluronic [poly(ethylene oxide) (PEO)−poly(propylene oxide) (PPO)−poly(ethylene oxide) (PEO)] micelles follow the Zimm scaling theory that predicts the diffusion coefficient to vary with solute molecular weight to the −0.5 power. The ratio of the diffusion coefficients in a 20% Pluronic gel-like liquid crystal phase to those in buffer solutions (without Pluronics) was approximately equal to 0.5 for all molecule sizes tested. PFGNMR water self-diffusion coefficient measurements in the gel phase and the solution phase of Pluronic micelles were interpreted within the context of volume averaging theory and known structural features of Pluronic micelles for various Pluronic concentrations. The result of combining the volume averaging theory and measurements of water and oligonucleotide self-diffusion indicates that the geometrical constraints of the Pluroni...