Synthesis and sonodynamic performance of spinel ferrites

Sonodynamic therapy has emerged as one of the most valuable treatment methods with low side effects and deep tissue penetration. As a representative inorganic sonosensitizer, spinel-type ferrites have many advantages such as high reactive oxygen species (ROS) production efficiency and stability. However, current studies have not explored how metal doping impacts the sonodynamic effect of spinel ferrites. Herein, we synthesized three kinds of spinel ferrite nanoparticles (ZnFe2O4, CoFe2O4, and MgFe2O4) and systematically investigated their sonodynamic performance. It is shown that three spinel ferrites are capable of producing singlet oxygen under ultrasound irradiation. Hydrogen peroxide further enhances the production of singlet oxygen, increasing the production rate by 1.05–2.31 times. The simultaneous existence of Co2+/Co3+ and Fe2+/Fe3+ redox couples in CoFe2O4 could convert more efficiently hydrogen peroxide into oxygen through catalytic reaction, providing more oxygen to promote singlet oxygen production. Thus, CoFe2O4 exhibits higher production efficiency than ZnFe2O4 and MgFe2O4. In vitro experiments demonstrate the good biocompatibility of CoFe2O4 nanoparticles and high ability to effectively kill cancer cells under ultrasound irradiation. In addition, CoFe2O4 shows good therapeutic efficacy in animal models of colon cancer. These findings highlight the great potential of ferrite sonosensitizer for cancer treatment.