PCL(4k)-PEG(5k)-RhB has a red fluorescent probe (rhodamine B) for protein/cell/nanoparticles labeling. The amphiphile polymer contains hydrophilic PEG block and hydrophobic polycaprolactone (PCL) block. Upon dispersion in water, the polymer can self-assemble to form micelles and can be used to encapsulate hydrophobic drugs. This polymer can be used to prepare drug-loaded nanoparticles for controlled release drug delivery. Reagent grade, for research purpose.