Spectroscopic and microscopic evidence of 2D boron nitride nanoflake interaction with doxorubicin

Doxorubicin (DOX) interaction with 2D boron nitride (BN) nanoparticles was studied experimentally and theoretically. The BN nanoparticles, namely nanoflakes, were obtained by direct liquid-phase exfoliation via preliminary stratification in a planetary ball mill from massive hexagonal BN. 2D BN nanoparticles and DOX/BN composites were characterized using visible steady-state, time-resolved fluorescence, FTIR and Raman spectroscopy, Coherent Anti-Stokes Raman Scattering (CARS) microscopy and density functional theory (DFT). The BN nanoflakes from 2 to 3 layers up to hundred nm in lateral direction possessed crystalline properties that formed the DOX/BN composites with fluorescence in the range of 520–750 nm that can be used in DOX detecting. The calculations revealed a notable electron transfer between the BN monolayer and the DOX molecule, which, however, is partly offset by the redistribution of charge within the monolayer. The energy of interaction of the BN with DOX was estimated as 1.96 eV, indicating that the DOX/BN composite formation is an exothermic process. The Fluorescence quenching of DOX/BN occurs with increased BN nanoparticle concentration. The optimal concentration for composite formation was chosen. In CARS imaging of the Lewis lung carcinoma cells after treatment with DOX/BN, brightly luminous points are observed inside the cells, indicating the accumulation of DOX/BN composites that can be used in bioimaging and theranostics.