Starch-based dual amphiphilic graft copolymer as a new pH-sensitive maltidrug co-delivery system

Amphiphilic dual graft copolymer composed of starch (St) as main chain, poly caprolactone (PCL) and poly (2-ethyl 2-oxazoline) (POX) as hydrophobic and hydrophilic side chains were synthesized and characterized successfully. Firstly, polycaprolactone with propargyl end group prepared and attached to the surface of azido starch (St-N3) which was prepared through incomplete azidation of starch tosylate, by click chemistry reaction. Thereafter, the polymerization of 2-ethyl-2-oxazoline initiated from the remaining tosyl groups of PCL-starch. Finally, polymerization of POX quenched by doxorubicin (DOX) as anticancer drug as well as terminator and curcumin (Cur) physically loaded in to the obtained copolymer. Dual graft copolymer (PCL-St-POX) as the co-delivery system containing covalently conjugated doxorubicin and non-covalently loaded curcumin could be promising biocompatible system to achieve combination therapy. The SEM images showed that resulting copolymer exhibited sphere-shaped particles ranging from 50 to 100 nm which is completely different from ungrafted starch. The release studies also revealed that obtained copolymer is pH-sensitive and the release rate was more favorable at acidic pH (tumor cells) than neutral pH (normal cells) for both drugs. [Display omitted] •New amphiphilic dual graft copolymer based on starch prepared•PCL and POX grafted to starch as hydrophobic and hydrophilic side chains•Obtained polymer used for codelivery of Cur and DOX anticancer drugs•Release study indicated that the release rate is effectively controlled by pH.•SEM showed sphere nanoparticles in range of 50–100 nm for graft copolymer.