Natural-based melanin nanoparticles for simultaneous chemo/photothermal therapy of melanoma

This study aimed to prepare dacarbazine (DTIC)-loaded melanin nanoparticles (MeNPs), characterize them in vitro, and evaluate their efficacy under NIR irradiation in a mouse model of melanoma. MeNPs were extracted from cuttlefish ink sacs by two-step centrifugation, and particle size, zeta potential, morphology, UV spectroscopy, elemental compositions, and chemical characterization of MeNPs were evaluated. Then, different suspension concentrations were irradiated under continuous-wave NIR 808 nm. The MeNPs were loaded with DTIC through electrostatic bonds and pH-dependent conformers. After in vitro characterization of the MeNPs loaded with DTIC, their efficacy was examined on mouse model of melanoma. Melanin nanoparticles extracted from cuttlefish ink showed a spherical morphology, an intensive photothermal effect, and outstanding biodegradability. The nanoparticles provided controlled-release conditions for DTIC. In vivo results showed that the group receiving DTIC-loaded MeNPs combined with NIR had significantly decreased (P value < 0.05) tumor volume compared to the group receiving normal saline as a treatment. The prepared nanoparticles also provided a more prolonged treatment than DTIC alone. Histopathological analysis revealed that the prepared nanoparticles combined with NIR caused extensive tumor shrinkage with minimal tumor residue, ulceration, and crust formation. These findings highlight DTIC-loaded MeNPs as a potential candidate for simultaneous photo- and chemotherapy of melanoma.