Poly(L-lactide-co-glycolide)-b-poly(ethylene glycol)-Iodolacetyl (PLGA-PEG-IA) is a functional amphiphilic block copolymer with Iodolacetyl group at the end of PEG. Iodoacetyl (IA) is a thiol (-SH) reactive group that can be used to modify biomolecules or other materials via their available thiol groups. Iodine group can be easily replaced by thiol group to form a stable carbon thiol bond. PLGA-PEG-IA is used to prepare micelles or nanoparticles with Iodoacetyl group on the micelle surface for bioconjugation via thiol substitution. Hydrophobic drugs is encapsulated in the PLGA core for targeted drug delivery.