Abstract: A therapeutic method for catalytically forming persulfide and/or polysulfide from hydrogen sulfide in vitro and in vivo using endogenously or exogenously released hydrogen sulfide is disclosed. That method comprises contacting cells in need including those under oxidative stress, traumatic brain injury (TBI) and hypoxia, or have an excess of hydrogen sulfide or deficiency of protein persulfidation with oxidized carbon nanoparticulate material in which the particles contain a plurality of carbonyl, hydroxyl and carboxyl substituents. Oxidized carbon nanoparticulate (OCN) material can be prepared from any of a variety of sources of which activated charcoal is preferred. A water-dispersible OCN material is described that does not need added hydrophilic polymers to provide dispersibility for at least 7 days at a concentration of about 1-5 mg/mL. These OCN materials also have a UV absorbance maximum in water of about 220 nm and pass through a 0.22 µm pore PES membrane.