PCL(4k)-PEG(3k)-SPDP allows self-assembly upon dispersion in water with polycaprolactone (PCL) core and PEG shell arrangement. The core regions can serve as reservoir for hydrophobic drugs. The shell region from PEG not only provides protection against degradation (enzymatic/hydrolysis) but also allows a stealth behavior which is a prerequisite for successful in vivo translation of nanomedicine to achieve long blood circulation and targeted delivery. The SPDP moiety can react with thiol molecule to form a disulfide linkage. Reagent grade, for research purpose.