Upconversion nanoparticles for photobiomodulation of neuronal cells

Abstract

Lanthanide doped upconversion nanoparticles (UCNPs) are promising luminescent materials for biomedical applications due to their ability to convert low energy, non-scattering NIR light to higher energy wavelength emissions. Sensing, bioimaging, drug delivery, therapy and photobiomodulation are the expected biomedical fields that will be impacted by the combination of NIR stimulation and upconversion emission. In the case of a typical upconversion from NIR, energy transfer occurs from Yb3+ sensitizer ions, which can be excited at 980 nm, to the activator lanthanide ions such as Er3+, Tm3+, Ho3+, Eu3+. Synthesis and design of the UCNPs and their introduction into the biological system requires stringent procedures due to the complex nature of biological environment at the cellular level. Our goal in this study is to develop small size, biocompatible UCNPs with a facile microwave assisted synthesis method and utilize them for photobiomodulation of neuronal cells. We aim to elucidate the intracellular mechanisms that are impacted by the upconversion photons emitted from designed nanotransducers towards stimulation of cell function. For this purpose, we sensitized blue emitting NaYF4 UCNPs and in-vitro laser irradiation experiments are conducted with NG108-15 (neuroblastoma-glioma hybrid) cells. Experiments are designed to further investigate the thermal and chemical effects that contribute to the resulted modifications in the cell function.