title: Near-infrared uncaging or photosensitizing dictated by oxygen tension.
abstract: Existing strategies that use tissue-penetrant near-infrared light for the targeted treatment of cancer typically rely on the local generation of reactive oxygen species. This approach can be impeded by hypoxia, which frequently occurs in tumour microenvironments. Here we demonstrate that axially unsymmetrical silicon phthalocyanines uncage small molecules preferentially in a low-oxygen environment, while efficiently generating reactive oxygen species in normoxic conditions. Mechanistic studies of the uncaging reaction implicate a photoredox pathway involving photoinduced electron transfer to generate a key radical anion intermediate. Cellular studies demonstrate that the biological mechanism of action is O2-dependent, with reactive oxygen species-mediated phototoxicity in normoxic conditions and small molecule uncaging in hypoxia. These studies provide a near-infrared light-targeted treatment strategy with the potential to address the complex tumour landscape through two distinct mechanisms that vary in response to the local O2environment.
authors.affiliation: Chemical Biology Laboratory, Center for Cancer Research, National Cancer Institute, Frederick, Maryland 21702, USA.
authors.forename: Erin D
authors.initials: ED
authors.lastname: Anderson
authors.affiliation: Chemical Biology Laboratory, Center for Cancer Research, National Cancer Institute, Frederick, Maryland 21702, USA.
authors.forename: Alexander P
authors.initials: AP
authors.lastname: Gorka
authors.affiliation: Chemical Biology Laboratory, Center for Cancer Research, National Cancer Institute, Frederick, Maryland 21702, USA.
authors.forename: Martin J
authors.initials: MJ
authors.lastname: Schnermann
mesh_terms: D016503:Drug Delivery Systems; D005786:Gene Expression Regulation; D006367:HeLa Cells; D006801:Humans; D008956:Models, Chemical; D010084:Oxidation-Reduction; D010100:Oxygen / Q000378:metabolism*; D010782:Photolysis; D010787:Photosensitivity Disorders; D017382:Reactive Oxygen Species
chemical_list: D017382:Reactive Oxygen Species; D010100:Oxygen