PCL(4k)-PEG(3k)-FITC is an amphiphilic block copolymer which can self-assemble in water with arrangement of polycaprolactone (PCL) as core and PEG as shell. The core can be used as lipophilic drugs reservoir while the shell can provide protection against degradation. The FITC dye can be used for staining cells/nanoparticles and can be easily traced by fluorescence microscopy. Reagent grade, for research purpose.