Oxygen-generating glycol chitosan-manganese dioxide nanoparticles enhance the photodynamic effects of chlorin e6 on activated macrophages in hypoxic conditions

This study aimed to investigate the use of glycol chitosan (GC) for the synthesis of MnO2 nanoparticles (NPs) and to evaluate whether the prepared GC-MnO2 NPs enhance the light-triggered photodynamic effects of chlorin e6 (Ce6) via the generation of oxygen and alleviation of hypoxia in lipopolysaccharide (LPS)-activated macrophages (RAW 264.7), which produce excessive amounts of reactive oxygen species (ROS). GC-MnO2 NPs were synthesized by a simple reaction between GC and KMnO4 in water. The prepared GC-MnO2 NPs were spherical in shape, with a mean diameter of approximately 60 nm. The particles effectively generated oxygen via H2O2-induced degradation under hypoxic conditions, which led to an increase in the singlet oxygen levels upon laser irradiation. Furthermore, GC-MnO2 NPs significantly enhanced the light-triggered photodynamic effects of Ce6 on activated macrophages under hypoxic conditions, as shown by the increased levels of cell death and cell membrane damage in activated macrophages. Therefore, these results suggest that GC can be used as an alternative natural polymer for the synthesis of MnO2 NPs and that oxygen-generating GC-MnO2 NPs enhance the light-triggered photodynamic effects of Ce6 on activated macrophages by alleviating hypoxia.