Chitosan-coated liposomes to stabilize and enhance transdermal delivery of indocyanine green for photodynamic therapy of melanoma

Indocyanine green (ICG) has been used clinically and noticed as a promising candidate for the topical melanoma photodynamic therapy (PDT). Despite its high potentials in topical PDT, the use of ICG has been hampered by the instability in aqueous solution. In the present study, chitosan-coated liposomes were adopted as a formulation strategy which could stabilize and enhance skin permeation of ICG. Chitosan-coating was verified by the significantly increased liposomal size and reversed zeta potential from negative to positive value by positive chitosan coating. Chitosan-coating liposomes protected ICG from degradation while uncoated liposomes did not. Moreover, they significantly increased cellular uptake and photocytotoxicity of ICG in B16-F10 melanoma cells in a chitosan-dependent manner. The skin permeation of ICG was also drastically improved by chitosan-coated liposomes. These findings emphasize the promising potential of ICG-loaded chitosan-coated liposomes for topical PDT of melanoma.