Biological effects of small sized graphene oxide nanosheets on human leukocytes

Since the discovery of graphene, there has been a wide range of the literature dealing withits versatile structure and easy binding of biomolecules as well as its large loading capacity. In theemerging field of immunotherapy, graphene and its derivatives have potential uses as drug deliveryplatforms directly into tumour sites or as adjuvants in cancer vaccines, as they are internalized bymonocytes which in turn may activate adaptive anti-tumoral immune responses. In this study, weexpose cells of the innate immune system and a human acute monocytic leukemia cell line (THP-1)to low doses of small-sized GO nanosheets functionalized with bovine serum albumin (BSA) andfluorescein isothiocyanate (FITC), to study their acute response after internalization. We show byflow cytometry, uptake in cells of GO-BSA-FITC reaches 80% and cell viability and ROS productionare both unaffected by exposure to nanoparticles. On the contrary, GO-BSA nanosheets seem tohave an inhibitory effect on ROS production, probably due to their antioxidant properties. We alsoprovided results on chemotaxis of macrophages derived from peripheral blood monocytes treatedwith GO-BSA. In conclusion, we showed the size of nanosheets, the concentration used and thedegree of functionalization were important factors for biocompatibility of GO in immune cells. Its lowcytotoxicity and high adaptability to the cells of the innate immune system make it a good candidatefor deployment in immunotherapy, in particular for delivering protein antigens to monocytes whichactivate adaptive immunity.