Photodynamic Therapy

Today the therapeutic use of light has evolved particularly owing to the milestone discovery and application of photodynamic therapy (PDT).PDT is a noninvasive, less aggressive alternative approach for the cancer treatment which is based on the three criteria – molecular oxygen, activating light and a photosensitizer. PDT implies the excitation of the sensitizing drug by visible or IR light followed by the activation of molecular oxygen from the ground-state triplet to its singlet state.(¹O₂). Due to its high reactivity, ¹O₂ disrupts different biological macrosystems, such as nucleic acids, proteins, and lipid membranes and eventually induces cell death. Various agents as a photosensitizer have been proposed for PDT nowadays such as clinically approved agents – porphyrins, phthalocyanines, or chlorins. There are several drawbacks that limits the transportation of drug in the bloodstream, hence, causes the aggregation-induced quenching in biological environments. In order to increase their efficiency and guarantee their therapeutic effects, encapsulation of drug is widely used – oligosaccharides, liposomes or nanoparticles.

In our research, QM/MM MD and classical MD simulations were conducted for the investigation of the structural and optical properties of photosensitizer. Geometry optimizations and single point energy calculations were performed with DFT and vertical excitations from ground state to stimulate the absorption spectra were obtained via TD-DFT.