PCL(5k)-PEG(5k)-BIO contains a polyester PCL block and a hydrophilic PEG block. This amphiphilic polymer is equipped with biotin which has strong binding affinity with streptavidin or avidin. In aqueous solution, the polymer self-assembles to form nanomicellar structure with PCL at the core being shielded by PEG. Hydrophobic drugs can be encapsulated in the core regions during the nanoparticles formation. Reagent grade, for research purpose.