Figure 7. DPPH radical scavenging activity of RL@ZnO nanoparticles.

RL@ZnO nanoparticles (0, 25, 50, 100, 150, and 200 mg/mL) were added to freshly prepared and stabilized DPPH solution (6×10⁻⁵ M), mixed and incubated at room temperature for 60 min. Then, DPPH radical scavenging potential was monitored by measuring the absorbance in the range A_460−600 nm wavelength using a UV-vis spectrophotometer. The peak intensity at A₅₁₇ nm gradually decreases in RL@ZnO nanoparticles. DPPH radical scavenging activity was measured at different time intervals: (A) 3, (B) 6, (C) 9, (D) 12, and (E) 15 months of the storage of RL@ZnO nanoparticles.