pH-responsive dual fluorescent core-shell microspheres fabricated via a one-step emulsion polymerization

Dual fluorescent core-shell microspheres with pH-responsive fluorescence resonance energy transfer (FRET) properties were fabricated via a one-step emulsion polymerization. The hydrophobic dye perylene and a hydrophilic fluorescein derivative were designed as donor and acceptor to realize the FRET from the core to the shell of the microspheres under alkaline conditions. Fluorescence spectra, lifetime and confocal images were used to characterize the observed pH-responsive FRET properties. The facile fabrication and controlled FRET of the microspheres will facilitate their applications in a wide variety of fields such as multicolor bio-labeling, high resolution spatial pH displays and optical devices.