Characterization and development of ZnO nanoparticles as a photosensitizer for diagnostic and treatment of cancer using lasers (abstract)

For over ongoing Biophotonics research we have characterized a cost expensive, and noninvasive Zinc Oxide (ZnO) nanoparticles (Np) and NRs of 11-15nm and nanorods (NRs) of 60-120nm diameter to use a photosensitizer in photodynamic therapy (PDT) of cancer. Confocal microscopy and light polarization techniques were employed to characterize the samples. Confocal microscopy of well known photosensitizer 5-Aminolavlonic acid (ALA) with ZnO and ALA without ZnO significant changes were seen and verified ZnO is tissue non toxic in dark, but enhances endogenous fluorescence in human cells. The fluorescence of ZnO with ALA is prominent if compared with other images. We observed that in dark ZnO is biosafe, biocompatible but cell toxic in the presence of 635nm laser light. ZnO conjugated photo-sensitizers being toxic under exposure of suitable light for malignant cells, and can be used as cancer cell killing drug. Mechanism of cytotoxicity appears to involve the generation of singlet oxygen inside the cell. The novel findings of cell-localized toxicity indicate a potential application of ZnO NRs with and without ALA can be used as efficient drug carrier, biomarker in diagnostic clinical applications, while ZnO NRs can be an appealing candidate for the PDT treatment of malignant diseases epically cancer. (author)