Turn-on fluorescence detection of apoptotic cells using a zinc(II)-dipicolylamine-functionalized poly(diacetylene) liposome.

A liposome-based fluorescence sensing system for apoptotic cells has been developed from stimuli-responsive poly(diacetylene)-liposomes for the first time. The combination of the liposome components, a phosphatidylserine-binding Zn(II)-dipicolylamine component and an alcohol-terminated component in the ratio of 2:1, has led to an efficient detection system for apoptotic cells, as demonstrated by confocal fluorescence microscopy and FACS analysis. The liposome shows a color change from blue to reddish purple and emits fluorescence in the turn-on mode upon interaction with phosphatidylserine. The present system thus avoids the washing steps required for "always-on"-type sensing systems.