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Fig. 3 | Journal of Biological Engineering

Fig. 3

From: Quantum dot therapeutics: a new class of radical therapies

Fig. 3

Bandgap and redox state engineering for therapeutic radicals. a-b) EPR spectra for UV illuminated ZnO and TiO2 nanoparticles, respectively, showing DMPO-OH peaks corresponding to the spin-trapped adduct of hydroxyl radicals. c-d) cyclic voltammograms for ZnO and TiO2, respectively, in deoxygenated water. Without a source of oxygen, TiO2 generates no radical signal but ZnO shows a peak corresponding to hydroxyl radicals – indicating superoxide-generating ability from TiO2 but not ZnO. e-f) reduction and oxidation state positions for ZnO and TiO2, respectively, as well as the effects of doping. Anionic doping shifts the VB and cationic doping shifts the reduction potential. g-h) EPR spectra for engineered ZnO and TiO2, respectively. Anionic and cationic doping of ZnO, as well as anionic doping of TiO2, yield hydroxyl production with visible light. Cationic doping of TiO2 shows no radical signal – indicating reliance on the reduction potential for superoxide generation. EPR spectra for N-TiO2/ZnS shows clear DMPO-OOH peaks corresponding to the superoxide radical adduct

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