Original ArticleMultifunctional near-infrared dye-magnetic nanoparticles for bioimaging and cancer therapy

•The nanoparticles IR820-CS-Fe3O4 have good stability in aqueous solution even for 8 days.•They have insignificant cytotoxicity on cell viability.•An outstanding T1/T2 MR imaging ability of IR820-CS-Fe3O4 nanoparticles was achieved.•The nanoparticles present an obvious killing effect on A375 cells after irradiation under NIR laser.

Theranostics based on nanoparticles have developed rapidly in the past decade and have been widely used in the diagnosis and treatment of liver cancer, breast cancer, and other tumors. However, for skin cancers, there are limited studies. In the present study, we successfully synthesized a theranostic nanoparticle by grating IR820 onto the surface of chitosan-coated magnetic iron oxide, IR820-CS-Fe3O4, showing an excellent magnetic resonance imaging (MRI) capability and cytotoxic effects against melanoma under irradiation with a near-infrared (NIR) laser (808 nm) in vitro. Furthermore, good stability for up to 8 days and negligible cytotoxicity were observed. These characteristics are important for biomedical applications of nanoparticles. In conclusion, we provide a novel and potential theranostic platform for melanoma treatment and detection.