Core‑shell type thermo‑nanoparticles loaded with temozolomide combined with photothermal therapy in melanoma cells

A novel coreshell type thermonanoparticle (CSTNP) coloaded with temozolomide (TMZ) and the fluorescein new indocyanine green dye IR820 (termed ITCSTNPs) was designed and combined with a nearinfrared (NIR) laser to realize its photothermal conversion. The ITCSTNPs were prepared using a twostep synthesis method and comprised a thermosensitive shell and a biodegradable core. IR820 and TMZ were entrapped in the shell and the core, respectively. Dynamic light scattering results demonstrated that the average hydrodynamic size of the ITCSTNPs was 196.4+/-3.1 nm with a zeta potential of 24.9+/-1.3 mV. The encapsulation efficiencies of TMZ and IR820 were 6.1 and 16.6%, respectively. Temperature increase curves under NIR laser irradiation indicated that the ITCSTNPs exhibited the desired photothermal conversion ef fi ciency. The in vitro drug release curves revealed a suitable release capability of ITCSTNP under physiological conditions, whereas NIR laser irradiation accelerated the drug release. Inverted fluorescence microscopy and flow cytometry results revealed that the uptake of ITCSTNPs by A375 melanoma cells occurred in a concentrationdependent manner. Confocal laser scanning microscopy results indicated that ITCSTNPs entered tumour cells via endocytosis and were located in intercellular lysosomes. In summary, the present study explored the photothermal conversion capability, cellular uptake, and intracellular localization of ITCSTNPs.