Fig. 4.

Macroscale demonstration of nanoparticle-mediated fusion. Sulforhodamine B encapsulated in small liposomes (SUVs) is released into GUVs, upon influx of Ca²⁺, only if the system is incubated with amphiphilic nanoparticles. (A) Time sequence of confocal fluorescence images showing fusion of liposomes with GUVs in the presence of nanoparticles. (B) Time sequence of confocal fluorescence images showing that fusion does not occur in the absence of nanoparticles. Time 0 represents a snapshot right before the addition of Ca²⁺. Note that the timescale of fusion in this case is limited by the diffusion of calcium toward the fusion sites. (Scale bars, 50 μm.)