Facile and green synthesis of α-Fe2O3 nanoparticles stabilized with chitosan for phototherapy with 808 nm laser irradiation

In this research, biocompatible α-Fe₂O₃ nanoparticles were prepared as an agent for photothermal and photodynamic therapy methods by combining green synthesis and hydrothermal methods. The addition of chitosan bio-polymer played a crucial role in this process, as it not only stabilized the suspension of nanoparticles but also enhanced their biocompatibility. This stability was confirmed by zeta potential analysis Various analyses such as transmission electron microscope, X-ray diffraction, UV-visible spectrum, and Fourier transform infrared spectrum were performed to determine the structural and optical characteristics of the nanocomposite. The average size of the spherical crystals of α-Fe₂O₃ nanoparticles was estimated at 43 nm using the Williamson-Hall equation. The corresponding band gap value of nanoparticles was estimated at 1.8 eV by drawing a Tauc diagram. Photothermal effects for several different concentrations of an aqueous solution of CS-nanocomposite were measured by an 808 nm laser with a power density of 1 W/cm^2, and the concentration of 5 mg/ml was chosen as the optimal concentration for use in photothermal therapy. The value of the photothermal conversion efficiency of this nanocomposite was determined at 7% using Roper's equation. To investigate the photodynamic properties of nanoparticles, a methylene blue probe was used to detect active oxygen species. Finally, an MTT assay studied the cytotoxicity of nanocomposite on AGS cells before and after laser irradiation. Under laser irradiation, cell viability at concentrations of 250ppm and 500ppm was 88% and 69%, respectively, compared to the control cells, confirming this nanocomposite's photothermal therapy and photodynamic therapy effects.