Emulsion self-assembly synthesis of chitosan/poly(lactic-co-glycolic acid) stimuli-responsive amphiphiles

An amphiphilic graft copolymer using chitosan (CS) as a hydrophilic main chain and poly(lactic-co-glycolic acid) (PLGA) as a hydrophobic side chain is prepared through an emulsion self-assembly synthesis. CS aqueous solution is used as a water phase and PLGA in chloroform is served as an oil phase. A water-in-oil (W/O) emulsion is fabricated in the presence of the surfactant span-80. The self-assembly reaction is performed between PLGA and CS under the condensation of EDC. Fourier transform IR (FTIR) spectroscopy reveals that PLGA is grafted onto the backbone of CS through the interactions between end carboxyl and amino groups of the two components. ¹H NMR spectroscopy directly indicates the grafting content of PLGA in the CS-graft-PLGA (CS-g-PLGA) copolymer is close to 25%. X-ray diffraction (XRD) confirms that the copolymer exhibits an amorphous structure. The CS-g-PLGA amphiphile can self-assemble to form micelles with size in the range of ≈100-300 nm, which makes it easy to apply in various targeted-drug-release and biomaterial fields. Chitosan can be dissolved into deionized water together with 1-hydroxybenzotriazole. A water-in-oil (W/O) chitosan and poly(lactic-co-glycolic acid) microemulsion is prepared and then a chitosan-graft-poly(lactic-co-glycolic acid) stimuli-responsive amphiphile is fabricated. The obtained amphiphile can self-assemble to form micelle in suitable solvents.