Reasonably retard O2 consumption through a photoactivity conversion nanocomposite for oxygenated photodynamic therapy.

Photodynamic therapy (PDT) brings excellent treatment outcome while also causing poor tumor microenvironment and prognosis due to the uncontrolled oxygen consumption. To solve this issue, a novel PDT strategy, oxygenated PDT (maintain the tumor oxygenation before and after PDT) was carried out by a tumor and apoptosis responsive photoactivity conversion nanocomposite (MPPa-DP). Under physiological conditions, this nanocomposite has a low photoactivity. While at H2O2-rich tumor microenvironment, the nanocomposite could react with overexpressed H2O2 to produce O2 and release high photoactivity chimeric peptide PPa-DP for oxygenated tumor and PDT. Importantly, when the PDT mediates cell apoptosis, the photoactivity of PPa-DP be effectively quenched and the O2 consumption appeared retard, which avoided further consumption of residual O2 on apoptotic cells. In vitro and vivo studies revealed that this nanocomposite could efficiently change photoactivity, reasonable control O2 consumption and increase residual O2 content of tumor after PDT.