The Use of Inorganic Compounds in Photodynamic Therapy: Improvements in Methods and Photosensitizer Design

Background: Nanotechnology has provided significant benefits to photodynamic therapy (PDT), which has revolutionized treatments of several diseases. The success of this versatile technique is governed by the sequential in situ generation of reactive oxygen species, after a suitable photosensitizer has been irradiated by a defined wavelength of light. While PDT provides a minimally-invasive and convenient method for the treatment of several afflictions, the efficiency of this therapeutic strategy still has potential for improvements. Several bodies of works within this realm have highlighted the use of inorganic compounds, which is pivotal for the development of photosensitizers (PSs), nanoparticles (NPs) and irradiation sources. Methods: The past decade of online patented reports based on PDT were reviewed. Results: The patented reports analyzed showcased the integration of nanomaterials and inorganic compounds into PDT. The patents were grouped according to the following categories, viz., “Nanoparticles in Photodynamic Therapy”, “Photosensitizers Incorporating Various Metal Centers”, and “Modifications to Light Delivery”. Conclusion: PDT is a suitable treatment option for several diseases however there are several challenges and limitations. The incorporation of NPs in the field of PDT is an extremely promising avenue which can be utilized to improve the execution of PDT. Furthermore, the use of inorganic compounds was noted to be frequented in the development of PSs and NP conjugates. The patents presented addressed the associated problems with PDT but there still remains an opportunity for continued research efforts so that more clinical applications are possible.