Anionic Star-Like Copolymers Based Nanosystems with Gold Nanoparticles and Temoporfin for Photodynamic Therapy of Carcinoma Cell Lines in vitro

Purpose: Photodynamic therapy (PDT) for carcinomas is an alternative treatment method for this pathology. PDT has a number of advantages, such as targeted therapy, weak side effects and high anticancer efficiency. Polymer branched nanocarriers in a combination with gold nanoparticles (AuNPs) can potentially reduce the side effects of hydrophobic photosensitizers (PS) and improve their pharmacokinetic properties. The aim of the study was to investigate the effect of anionic star-like copolymers of the dextran-graft-(polyacrylamide-co-polyacrylic acid) with a dextran core of 20 kDa and 500 kDa on the combined AuNPs and Temoporfin PDT of squamous cell carcinoma. Patients and Methods: AuNPs were synthesized in situ in a matrix of dextran-graft-(polyacrylamide-co-polyacrylic acid) hybrid polymers with a dextran core of 20 kDa (D20-PAAan) or 500 kDa (D500-PAAan) with grafted Polyacrylamide (PAA) chains. The size and morphology of nanosystems were characterized by DLS and scanning electron microscopy. Cytotoxicity and phototoxicity studies were performed on the Hep-2, KB and MAEC cell lines in vitro. The cytotoxicity of the individual components of the nanosystems, cell inactivation under PDT conditions following irradiation with 660 nm light (15 J/cm 2 ), intracellular reactive oxygen species (ROS) levels, mitochondrial membrane potential (ΔΨ m ), and overall cytomorphological changes were assessed. Results: The optimal concentrations of gold (as AuNPs) 4.3 μg/mL, polymer 5.0 μg/mL and Temoporfin 0.625 μg/mL were determined, at which the maximum plasmon enhancement is achieved with the competing effect of Förster resonance energy transfer. The cytotoxicity of D20-PAA (100 μg/mL) was 80%, 65%, and 45% against KB, Hep-2 and MAEC cells respectively. The cytotoxicity of D500-PAA at the same concentration did not exceed 40%. ROS levels were increased 1.8-fold in Hep-2 cells following incubation with the ternary nanosystems and subsequent irradiation, regardless of the carrier polymer. ΔΨ m was increased 1.4-fold in Hep-2 cells treated with D20-PAAan/AuNPs/Tem and 2.1-fold in cells treated with D500-PAAan/AuNPs/Tem followed by 660 nm light irradiation. In KB and MAEC cells, these changes were less pronounced. Conclusion: D20-PAAan based systems showed a stronger influence on cells by briefly changing the intracellular ROS levels and ΔΨ m . Nanosystems based on D20-PAAan should be more promising for PDT applications.