• Effect of Dopamine Concentration on Polydopamine Nanoparticle Synthesis and Antioxidant Properties
  • Mina Bordbar,1 Ali Khatibi,2,*
    1. Department of Biotechnology, Faculty of biological sciences, Alzahra University
    2. Department of Biotechnology, Faculty of biological sciences, Alzahra University


  • Introduction: Polydopamine (PDA) has gained significant attention for its multifunctional properties in material science and biomedical applications. The polymerization of dopamine, a simple and versatile catecholamine, leads to the formation of PDA coatings on various surfaces. Understanding the relationship between PDA synthesis conditions, particle characteristics, and antioxidant properties is crucial for harnessing its potential in biomedical and environmental applications. In this study, we investigate the synthesis of PDA at varying dopamine concentrations and its subsequent antioxidant capabilities.
  • Methods: Polydopamine was synthesized under controlled conditions at 37°C for three days with different dopamine concentrations (0.04 mg/ml, 0.16 mg/ml, 0.64 mg/ml, and 1.9 mg/ml). The antioxidant properties of each PDA sample were evaluated using UV-Vis spectrometry and a ROS scavenging test based on the Fenton reaction. ROS clearance percentages were calculated for each concentration, and the physical characteristics of the PDA nanoparticles were analyzed through sedimentation observations and particle size measurements.
  • Results: Our results revealed a concentration-dependent synthesis of PDA. Lower dopamine concentrations led to faster polymerization, resulting in smaller and lighter nanoparticles with no observable sedimentation. Conversely, higher dopamine concentrations produced larger and heavier particles, accompanied by sedimentation. Interestingly, the antioxidant effect of PDA exhibited a positive correlation with dopamine concentration. At the lowest concentration (0.04 mg/ml), ROS clearance was 29%, and at 0.16 mg/ml, it increased to 30%. Substantially higher ROS clearance rates were observed at the higher concentrations, reaching 80% at 0.64 mg/ml and 75% at 1.9 mg/ml. This suggests that PDA synthesized at higher dopamine concentrations possesses enhanced ROS scavenging capabilities.
  • Conclusion: In summary, our study demonstrates that the concentration of dopamine during PDA synthesis significantly influences both the physical characteristics of the nanoparticles and their antioxidant properties. Lower dopamine concentrations favor faster polymerization, yielding smaller, lighter PDA nanoparticles without sedimentation. In contrast, higher dopamine concentrations result in larger, heavier particles accompanied by sedimentation. Notably, the antioxidant effect of PDA increases with higher dopamine concentrations, indicating its potential as an efficient ROS scavenger. These findings provide valuable insights into tailoring PDA properties for specific applications, such as drug delivery, tissue engineering, and environmental remediation.
  • Keywords: Polydopamine, ROS scavenging, antioxidant properties, nanoparticle synthesis