Eumelanin-Fe3O4 hybrid nanoparticles for enhanced MR/PA imaging-assisted local photothermolysis.

In this work, we report on biodegradable eumelanin-Fe3O4 hybrid nanoparticles (euMel-Fe3O4 NPs) for multiple imaging-assisted local photothermolysis. The euMel-Fe3O4 NPs are rationally prepared via a facile one-step co-precipitation method in the aqueous phase in the presence of eumelanin. The obtained NPs exhibited high stability and aqueous dispersity. euMel-Fe3O4 NPs could provide T2-weighted magnetic resonance (MR) and photoacoustic (PA) imaging contrast enhancement prior to the treatment, due to their high r2 relaxivity that was determined to be 245.88 mM-1 s-1 (a value higher than those for other commercially available iron oxide NPs) and good PA signal intensity. Besides, with effective NIR absorbance, the euMel-Fe3O4 NPs promoted an effective photothermolysis treatment in an experimental mouse model of cancer. Cytotoxicity and in vivo histological examination demonstrated no appreciable toxicity. Our work suggests that euMel-Fe3O4 NPs could be proposed as a potential class of theranostic nanoplatform with multiple imaging modalities for cancer therapy.