PCL(3k)-PEG(5k)-BIO has a polycaprolactone (PCL) hydrophobic block and a PEG hydrophilic block. The biotin is tethered to the PEG and can bind strongly to avidin or streptavidin for protein labeling. The polymer can self-assemble to form micelles in water and be used to encapsulate drugs in drug delivery. Reagent grade, for research purpose.