In recent decades, new methods of cancer treatment have been developed. One of these methods is photodynamic therapy (PDT), which is non-invasive and based on the generation of reactive oxygen species (ROS) when light interacts with photosensitizers (PS). However, photosensitizers often have low solubility and reduced bioavailability under physiological conditions. To address this issue, nanocarriers have been created to deliver photosensitizers more effectively, increasing the depth of penetration into cellular structures and enhancing the therapeutic effect of PDT.
The paper presents nanocarriers obtained through the nanoemulsion polymerization reaction between homologous methyluracil derivatives (4-(3,6-dimethyluracil)-butyl acrylate or 3-(3,6-dimethyluracil)-propyl acrylate) and N,N'-bis(acryloyl)cystamine. These methyluracil derivatives form the shells of the nanocarriers, while N,N'-bis(acryloyl)cystamine, dissolved in DMSO, acts as the dispersed phase to form a hydrophobic core. Porphyrin derivatives with various substituents at the meso-position are encapsulated within the core of these nanocarriers. According to transmission electron microscopy data, carrier sizes ranged from 50 to 200 nanometers (nm), and nanocarriers containing a glycoporphyrin derivative had the smallest hydrodynamic diameters.
The cores, formed by N,N'-bis(acryloyl)cystamine, contain disulfide bonds that can be reduced by intracellular antioxidants such as glutathione. These antioxidants are often found in tumor environments. The reaction of reducing the disulfide bond leads to the disintegration of the particles and the release of PS. This process has been confirmed by the fluorescence method, which shows an increase in emission intensity over time when glutathione is added to the carrier solution.
The formation of singlet oxygen upon irradiation of nanocarriers with PS was confirmed using 1,3-diphenylisobenzofuran (DPBF) and UV spectroscopy. PS in nanocarriers based on 4-(3,6-dimethyluracil)-butyl acrylate generated singlet oxygen at almost twice the rate of individual PS.
