Photobleaching of non-covalent complexes of folic acid and photosensitizers

Photodynamic therapy (PDT) is an alternative treatment for the control of malignant diseases. It is based on the action of a photosensitizer (PS) molecule, which, upon being excited by light in a determined wavelength, reacts with oxygen and generates reactive oxygen species in target tissues, leading to cell death. We perform the non-covalent binding of PS’s with folic acid (FA) that have specific interactions with receptors, which are overexpressed on tumor cells to improve the targeted nature of PDT. The photobleaching of complexes and their components also was studied. The study showed that PS’s were actively bonded with FA non-covalently, with the molar ratio of components up to [FA]/ [PS] = 10.8, depending on the structure of the PS. As the duration of illumination increases, the photostability of the samples decreases. 20 % glycerin had a stabilizing effect on all samples. Therefore, the presence of glycerin in the solution is advisable to obtain stable non-covalent complexes.