Professor Yeu-Chun Kim’s research team from the Department of Chemical and Biomolecular Engineering has developed a photodynamic therapy (PDT) based on near-infrared (NIR) fluorophore, supplementing the flaws in existing PDTs. With PhD candidate Il Koo Noh as the lead author, the project has been carried out as a joint research with Professor Ji-Ho Park’s team from the Department of Bio and Brain Engineering.
PDT uses light instead of drug administration or genetics. It involves exposing a target body part to a laser beam, which converts oxygen into toxic active oxygen in order to induce apoptosis of the cells. This is a common treatment, but if the existing contrast medium of a PDT is of too low efficiency, it may in turn cause the mutation of cancerous cells, leading to side-effects such as reduced curative effects. Therefore, to maximize the remedial value, it is important to focus high concentrations on the desired body part, and research on focusing the treatment effects on the cellular organelle mitochondrion is in progress.
Active oxygen made by PDT contrast mediums attacks mitochondrial membranes to cause apoptosis. The mitochondria of a cancerous cell tend to have high potential differences between the inner and outer mitochondrial membranes, so the insertion of positively-charged, hydrophobic materials is more favourable.
To maximize these effects of PDT contrast mediums, the research team has developed a material made up of a mitochondria-targeting triphenylphosphonium group, bromide for fortifying the PDT, and an amine group for increasing solubility. This material was then injected into a tumor-transplanted mouse. When light was concentrated on the tumor area to induce anticancer effects, the team was able to confirm that the targeted therapy was carried out successfully.
The material uses a 662 nm laser originating from extinction and radiation in the NIF light range. Whereas the existing PDT contrast material uses visible light, which shows a depth within the micrometer range, the material developed by the research team demonstrated penetrability into millimeters. This shows that the material is over 100 times more sensitive than the existing contrast medium.
“The laser may rest on the mitochondria of the cancerous cell for a long time and only the targeted area is treated effectively without adverse side effects”,” explained Noh, who led the research. “After treatment, the material disassembles without toxicity, overcoming the previous disadvantages of earlier contrast media.”
“Through improving preexisting medications and treatments”, added Professor Kim, “new platform of treatments may be developed with reduced side effects and practicality in various diseases.”