Dynamics of Phospholipid Membrane Growth and Drug-Membrane Interactions Probed by Atomic Force Microscopy

Atomic Force Microscopy (AFM) has been used to probe the dynamics of phospholipid membranes. The kinetics of the growth processes and the time required to make large scale, stable supported phospholipid bilayers on mica substrates were examined and are shown to be second order. These studies ensure the formation of stable bilayers for experiments where AFM is used to probe the dynamics of the bilayer when it is interacting with the drug chlorpromazine (CPZ). Data generated in the presence of CPZ demonstrated a change in transition temperature. The decrease in transition temperature is caused by a disruption of the layer giving rise to defects. The time scale over which these defects occur was also measured. These AFM measurements give an insight into the interaction mechanism of CPZ with membranes at near molecular levels. Additionally, the AFM images clearly show the effect on the membrane of phospholipidosis, a type of lipid storage disorder.