Photodynamic therapy using Luciferase nanoconjugate as a treatment for colon cancer
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Photodynamic Therapy (PDT) has proven itself in previous studies to be a successful therapeutic treatment for surface tumors, but its effectiveness is limited to only shallow depths that allow for the penetration of light. This study demonstrates that we have improved upon the conventional method of PDT and have overcome the previous depth limitation by creating the light at the location of the tumor in situ. We conjugated a bioluminescent protein, Luciferase, to a semiconductor nanoparticle, TiO2, and with a cell specific antibody, anti-EGFR monoclonal antibody C225. The nanoconjugate, TiDoL-C225, was then activated by ATP and Luciferin in a reaction that creates reactive oxygen species (ROS) and induces apoptosis in the tumor cells. We created the optimal nanoconjugate synthesis protocol to make TiDoL and TiDoL-C225 for use in the PDT treatment. The TiDoL-C225 nanoconjugate is able to bind specifically to colon caner cells as the C225 antibody recognizes EGFR expressed at the surface of the cells, and further, when activated it will react only with the tumor cells. The optimal cell staining protocols were developed to visualize the treatment process and later analyze with the laser confocal microscope. The TiDoL nanoconjugate was found to only be operational and effective at killing tumor cells after being activated by Luciferin and ATP, which then enhances the control we have over the therapy. The TiDoL-C225 nanoconjugate increases the efficacy of binding to tumor cells and the speed of the reaction in the cells to begin apoptosis, even in lower concentrations when compared to the free TiDoL nanoconjugate. Finally, our PDT technique allowed us to monitor the tumor cells as they begin to undergo apoptosis in less than five minutes after the Luciferin was added to activate the reaction. The advantage of our method of PDT with the TiDoL-C225 nanoconjugate is that it can be used for early detection as well as developed into an effective treatment for cancers in all depths of tissue.