Fe-quercetin nanozyme: unveiling the chemistry of phenol metal-ligand complexes in reactive oxygen species scavenging

Abstract Reactive oxygen species (ROS) are necessary for cellular metabolism and defence signals, however, imbalanced amounts can lead to major health consequences. Conventional methods use natural enzymes as well as chemical antioxidants for scavenging ROS. Natural enzymes exhibit limitations related to stability, cost-effectiveness, and efficacy in physiological environments. To address these challenges, we synthesized an iron-quercetin (FeQ) coupled nanozyme that integrates iron's catalytic characteristics with quercetin’s antioxidant capabilities. The ROS scavenging activity of nanozyme was analyzed using crystal violet dye and Fenton reaction. We optimized various factors that influence FeQ nanozyme activity, including hydrogen peroxide (H 2 O 2 ), dye, and nanozyme concentrations. This research evaluates the effect of H 2 O 2 on ROS generation across a concentration range of 1–15 mM, demonstrating that a 10 mM concentration achieved a degradation efficiency of 65.7%. The optimal dye concentrations were determined to range between 68.6 and 274.4 μM, achieving a degradation efficiency of 75.78% with a concentration of 137.2 μM. The impact of the nanozyme was evaluated at concentrations ranging from 0.04 to 0.1 mg ml −1 , with notable scavenging of ROS observed at 0.08 mg ml −1 , resulting in a degradation efficiency of 72.48%. The FeQ nanozyme, with a concentration of 0.08 mg ml −1 , effectively scavenged ROS from 10 mM H 2 O 2 , while maintaining the integrity of the dye at a concentration of 137.2 μM. Approximately 70% of dye degraded under control conditions, but only 8% in the presence of nanozymes. FeQ nanozymes ROS scavenging properties suggest therapeutic implications for neurological disorders, cancer, and inflammation.