Abstract

Photoisomerization properties of amphiphilic stilbazolium markers are used to provoke photo-induced flip-flop in model lipid bilayer membranes. The flip-flop mechanism and dynamics are determined using simultaneous two-photon excited fluorescence and second harmonic generation microscopy. In absence of illumination, trans- is the dominant conformation, however when an illumination pulse is applied to the membrane markers, photo-induced isomerization provokes a significant increase in the cis- population, whose flip-flop rate was determined to be at least a thousand times greater than that for the trans-marker. Following the illumination pulse, all markers rapidly relax to the trans-conformation.

© 2003 SPIE