Nose-to-Brain Translocation and Cerebral Biodegradation of Thin Graphene Oxide Nanosheets

Abstract

Summary Understanding the interactions of graphene oxide (GO)-based materials with biological systems is critical due to the potential applications of these materials. Here, we investigate the extent to which single- to few-layer GO sheets of different controlled lateral dimensions translocate from the nose to the brain following intranasal instillation. We explore tissue location and in vivo biodegradability of the translocated materials using various techniques. Mass spectrometry and confocal Raman analyses indicate that trace amounts of GO undergo nose-to-brain translocation in a size-dependent manner. The smallest GO-sheet size category (us-GO, 10-550 nm) gains the greatest access to the brain in terms of quantity and coverage. Confocal Raman mapping and immunofluorescence combinations show that in vivo, us-GO resides in association with microglia. Point-and-shoot Raman spectroscopy shows that trace quantities of us-GO are maintained over 1 month, but undergo biodegradation-related changes. This study adds to growing awareness regarding the fate of graphene-based materials in biological systems.