Modulating dual carrier-transfer channels and band structure in carbon nitride to amplify ROS storm for enhanced cancer photodynamic therapy

Abstract

Graphite carbon nitride (CN) eliminates cancer cells by converting H₂O₂ to highly toxic •OH under visible light. However, its in vivo applications are constrained by insufficient endogenous H₂O₂, accumulation of OH⁻ and finite photocarriers. We designed Fe/N_V-CN, co-modified CN with nitrogen vacancies (N_V) and ferric ions (Fe³⁺). N_V and Fe³⁺, not only adjust the band structure of CN through quantum confinement effect and the altered coupled oscillations of atomic orbitals to facilitates •OH production by oxidizing OH⁻, but also construct dual carrier-transfer channels for electrons and holes to respective active sites by introducing stepped electrostatic potential and shortening three-electron bonds, thereby involving more carriers in •OH production. Fe/N_V-CN, the novel reactor, effectually produces vast •OH under illumination by expanding OH⁻ as the raw material of •OH and augmenting carriers at active sites, which induces cancer cell apoptosis by disrupting mitochondrial function for significant shrinkage of Cal27 cell-induced tumor under illumination. This work provides not only an effective photosensitizer avoiding the accumulation of OH⁻ for cancer therapy but also a novel strategy by constructing dual carrier-transfer channels on semiconductor photosensitizers for improving the therapeutic effect of photodynamic therapy.