Time-differential PAC parameters for 111In-DTPA labelled vesicles

The perturbed angular correlation of γ-rays from labelled phospholipid vesicles has been found to be caused by approximately equal contributions from static and time-dependent effects. A comparison between the PAC parameters from the labelled vesicular system and the labelled DTPA reporter molecule alone suggests that the PAC nuclide is located within, and not on, the bilayer wall. When the vesicles are lysed with triton detergent, there appears to be a reduction in the time-dependent electric quadrupole field gradient seen by the PAC nuclide but not significant reduction in the size of the bilayer fragments.