X-ray induced singlet oxygen generation by nanoparticle-photosensitizer conjugates for photodynamic therapy: determination of singlet oxygen quantum yield.

ABSTRACT: Singlet oxygen is a primary cytotoxic agent in photodynamic therapy. We show that CeF3 nanoparticles, pure as well as conjugated through electrostatic interaction with the photosensitizer verteporfin, are able to generate singlet oxygen as a result of UV light and 8?keV X-ray irradiation. The X-ray stimulated singlet oxygen quantum yield was determined to be 0.79?±?0.05 for the conjugate with 31 verteporfin molecules per CeF3 nanoparticle, the highest conjugation level used. From this result we estimate the singlet oxygen dose generated from CeF3-verteporfin conjugates for a therapeutic dose of 60?Gy of ionizing radiation at energies of 6?MeV and 30?keV to be (1.2?±?0.7)?×?10(8) and (2.0?±?0.1)?×?10(9) singlet oxygen molecules per cell, respectively. These are comparable with cytotoxic doses of 5?×?10(7)-2?×?10(9) singlet oxygen molecules per cell reported in the literature for photodynamic therapy using light activation. We confirmed that the CeF3-VP conjugates enhanced cell killing with 6?MeV radiation. This work confirms the feasibility of using X- or ?- ray activated nanoparticle-photosensitizer conjugates, either to supplement the radiation treatment of cancer, or as an independent treatment modality.

SUBMITTER: Clement S 

PROVIDER: S-EPMC4730142 | biostudies-literature | 2016 Jan

REPOSITORIES: biostudies-literature