Device Fabrication and Photosensitizing Role of ZnO Nanostructures in Photodynamic Therapy of Cancer

Abstract: In nanoscience and nanotechnology, zinc oxide (ZnO) is gaining much research attention due to direct wide band gap (3.3 eV), large exciton binding energy (60 meV), and deep level defects emissions that cover the whole visible range. ZnO nanorods (NRs) in comparison to normal bio molecules and large surface area to volume ratio, allow them to interact within the cell thus are used as convincing intracellular carriers of photosensitizers. Vertical NRs are wave guiding cavities enhancing the light extraction efficiency from devices and are stable photosensitizing agents with their biophotonic, and biodegradation properties, therefore are appealing candidates for the photodynamic therapy of cancer.The heterojunction LEDs of ZnO NRs/p-GaN are best choice to take the advantage of GaN ideal blue-light emission and fabricated LEDs explore the potential of white LEDs with superior performance. The main objective of this thesis is not only to fabricate ZnO NRs/p-GaN, or ZnO nanotubes (ZNTs)/p-GaN heterostructures, but also to investigate their optical properties for photodynamic therapy. These LEDs have showed enhanced EL intensity covering the visible band (425–750 nm).ZnO nanorods are grown on the borosilicate glass capillaries (0.7 μm diameter) and then conjugated with photosensitizer. Such glass capillaries having ZnO nanorods complex with photosensitizer on them are used as pointer for intracellular mediated photochemistry in cells to achieve their necrosis. Mitochondrial staining of melanoma and foreskin fibroblast cells was done by Mitotracker Red with the aim of targeting the specific organelle with the prepared ZnO nanowires (NWs) Femtotip to see ROS production. Cytotoxic effects of nanometallic oxides e.g. ZnO-NRs, MnO2 NRs, and Fe2O3 NPs individually and their ligands with photosensitizers in osteosarcoma (U2OS) cells are also explored. Thus bare and ligands of nanometallic oxides, with particular focus of ZnO nanowires are having significant and convincing cytotoxic effects via the liberation of reactive oxygen species as well as Zn+2 ions in labeled cells, thus can be assigned as anticancer agents for breast cancer, melanoma cancer and osteosarcoma cells.