Photodynamic therapy, which is mostly used in the treatment of skin cancers and known for its low side effects, cannot give the desired results when cancer cells are located in deep areas where rays cannot easily reach.
Boğaziçi University Chemistry Department faculty member Assoc. Dr. Sharon Çatak and his team started a research that would eliminate this disadvantage of photodynamic therapy and double the beam-trapping capacity of molecules responsible for capturing rays. In the project led by Sharon Çatak, if two photon-absorbing antennas are placed on the molecules, how these molecules behave inside the cell will be calculated and the results obtained will guide the development of photodynamic therapy for the treatment of organ cancers located in deep tissues.
Boğaziçi University Chemistry Department faculty member Assoc. Dr. The project titled “Design of new photo sensitizers for photodynamic therapy” led by Şaron Çatak has been awarded within the scope of TÜBİTAK 1001. In the project that is planned to last two years, Assoc. Dr. With Çatak, one undergraduate, two graduate students and a doctoral student are also involved as a researcher.
A cancer treatment with minimal side effects
Photodynamic therapy (FDT), one of the approaches that do not require surgical intervention in cancer treatment, has fewer side effects on the body than other cancer treatments. Assoc. Dr. Çatak explains how this treatment method works as follows: “The drugs given to the body in photodynamic therapy actually spread to the whole body, but these drugs are drugs that are activated by radiation. For this reason, only the cancerous area to be treated is irradiated and the drugs in that area are activated and it is possible to work in a target-oriented way. Drugs that are not activated are also eliminated from the body. Therefore, the side effects of the treatment on the body are minimized. In addition, its cost is very low compared to other cancer treatments. "
The only disadvantage of photodynamic therapy is when cancer cells are located in deep tissues where rays cannot easily reach. Assoc. Dr. Çatak said, “The molecule that will effectively absorb the rays in the deep tissue is being investigated today. Therefore, FDT treatment has not been performed so far in deep tissue tumors. However, in this project, we will try to overcome this limitation of FDT by proposing drug molecules that can also be activated in deep tissues, ”notes that they aim to increase the effect of photodynamic therapy.
The beam capture capacity of molecules will double
Stating that a drug molecule called PS (photosensitizer) molecule is used in photodynamic therapy, Assoc. Dr. Sharon Çatak states that they aim to increase the effectiveness of the treatment by adding antennas to these molecules: “We will add two photon-absorbing antennas to the FDA-approved PS molecule we will work on. When two photons-absorbing antennas are added to these chlorine-derived molecules, they will be able to capture twice as much light than normal. When the PS molecule receives the rays, the singlet first becomes excited, then depending on the photophysical properties of the molecule, the singlet goes from excited state to triplet excited state. On the other hand, by encountering oxygen in the body environment, which is at the triplet level by nature, the triplet excited PS molecule transforms the oxygen into a reactive state by transferring energy to oxygen. In other words, the molecule's job here is to absorb the beam and transfer the energy provided by that beam to oxygen. In short, the oxygen that does the cell breakdown is not the PS molecule; however, this molecule is responsible for reacting oxygen. "
According to Çatak, the fact that photodynamic therapy can be more effective for cancer cells located in deep tissues depends on the ability of PS molecules to absorb more rays: “We want to add two photon-absorbent antennas on the PS molecule so that it can absorb energy in deep tissues. Because the injected PS molecule cannot absorb effectively at this wavelength even if it goes to deep tissue, and therefore the FDT activity of this molecule is not possible here. However, the high wavelength light (red light) used in the treatment can penetrate deep tissue. With this approach, when we add two photon-absorbing antennas to the molecule, we will double the number of photons absorbed. Also later on, we will have the chance to test how these molecules move through body tissue under laboratory conditions and how drugs interact with the cell membrane. "
A guiding work for experimental chemists
Emphasizing that the project is a purely theoretical molecular modeling study and will proceed with simulations to be made in computer environment, Assoc. Dr. Sharon Çatak explains the advantages of the project's outputs as follows: “There are already laboratories where the molecules we mentioned are synthesized, we will investigate how they behave inside the cell by modeling. The advantage of these studies in computational chemistry comes from being able to find the photophysical properties of molecules in great detail. We give experimental chemists prediction about which molecule they can modify in what way, so they can synthesize molecules according to what we find by calculating instead of repeatedly making trial and error, and we speed up the process. "