Excitable Oil Droplets - FRET Across a Liquid-Liquid Phase Boundary

FRET forms the basis for energy transfer in biological systems and organisms and it has become an investigative tool in the analysis of protein-protein interactions and in the study of semiconductors (SC). Until now, FRET has been restricted to the simultaneous presence of both components in the same phase. Here, we report on the first successful prototype demonstrating interfacial FRET. This innovative FRET between inorganic SC-nanoparticles and illuminating protein chimeras takes place across an oil/water interface. As a 'proof of concept' oil droplets were stabilized by hydrophobin-derivatives in aqueous solution. These proteins possess the ability to attach fused functional domains close to an interface. Moreover, an optically active nanostructure directly docks to the hydrophobin at the oil/water interface. Due to its modular design, this signal amplification array has the potential to be exploited in numerous fields ranging from biosensors, biotechnology to medical applications.