Metal-organic layers (MOLs) and metal-organic nanoplates (MOPs) comprising photosensitizers are described. The MOLs and MOPs can also include moieties capable of absorbing X-rays or other ionizing irradiation energy and/or scintillation. Optionally, the photo sensitizer or a derivative thereof can form a bridging ligand of the MOL or MOP. Also described are methods of using MOLs and MOPs in photodynamic therapy, X-ray induced photodynamic therapy (X-PDT), radiotherapy (RT), radiodynamic therapy, or in radiotherapy-radiodynamic therapy (RT-RDT), either with or without the co-administration of another therapeutic agent, such as a chemotherapeutic agent or an immunomodulator.