mPEG(2k)-PCL(5k)-COOH is one of bioconjugation amphiphilic polymers which can react with amine molecule, such as protein or peptide, in the presence of activating agent (HATU or EDC). The polymer forms micelles in water where the core contains polycaprolactone (PCL) and the shell is made of PEG. This polymer can be used to prepare nanocarrier for therapeutic agents/drugs. Reagent grade, for research purpose.