Determination of the self-diffusion coefficient of intracellular water using PGSE NMR with variable gradient pulse length

A new pulsed-gradient spin-echo NMR protocol for assessing the local self-diffusion coefficient D0 of water confined within living cells is proposed. Equations for the apparent mean-square displacement as a function of the effective diffusion time td and the duration of the displacement-encoding gradient pulses δ are derived. The standard method of estimating D0 - reducing td until the influence of collisions between the water molecules and the plasma membrane can be neglected - often fails because of the small size of typical cells. As demonstrated here, the decrease of the apparent with increasing δ at constant td can be utilized to measure D0.