Hydrophilic carbon clusters as therapeutic, high-capacity antioxidants.

•Most antioxidants show little efficacy following trauma such as TBI or stroke.•Carbon nanoparticles quench O2•−, affording no downstream radicals.•Each nontoxic nanoparticle can annihilate thousands of O2•− molecules; the same nanoparticles are selective, being inert to NO•.•Prospects are shown for the treatment of numerous O2•−-induced human pathologies.