Pro- and anti-oxidant properties of near-infrared (NIR) light responsive carbon nanoparticles.

Elemental carbon nanomaterials (ECNMs) are redox active agents that can be exploited to purposely modify the redox balance of cells. Both pro- or antioxidant properties have been reported. However, to the best of our knowledge, there are not comprehensive studies exploring both properties on the same material in view of a potential application in medicine. At the same time, the effect of the bulk structure on the pro/antioxidant properties is poorly known. Here, carbon nanoparticles (CNPs) derived by glucose with definite size and shape have been prepared, and their redox properties evaluated in cell free systems in the dark or following activation with a Near Infrared (NIR) laser beam (945 nm, 1.3 W/cm2). We found that, when irradiated with NIR, CNPs efficiently generate heat and singlet oxygen (1O2), a property that can be exploited for dual photo-thermal (PT)/photodynamic (PD) therapy in cancer. On the other hand, in the absence of photo-activation, CNPs react with both oxidant (hydroxyl radicals) and antioxidant (glutathione) species. When tested on a murine macrophages cell line (RAW 264.7) CNPs were clearly antioxidant. Furthermore, albeit efficiently internalized, CNPs do not exert cytotoxic effect up to 80 µg/ml and do not exacerbate TNF-α-mediated inflammation. Overall, the results reported herein suggest that CNPs may represent a new class of safe nanomaterials with potential applications in medicine.