*3.2. Determination of Preparation Conditions of SeCS Nanoparticles*

SeCS nanoparticles were prepared according to the method as described in previous study with some modifications [23]. CS was dissolved in 30 mL of deionized water and the concentration of CS was 0.05, 0.1, 0.15, 0.2, and 0.25 mg/mL. Different molar ratios of Na2SeO3 to Vc (Na2SeO3: Vc = 1:2, 1:4, 1:6, 1:8, 1: 10) were added to CS solution and stirred at different temperatures (25 ◦C, 40 ◦C, 55 ◦C, 70 ◦C, 85 ◦C) for different times (1 h, 2 h, 3 h, 4 h). Then, the solution was dialyzed against double-distilled water for 48 h with a dialysis bag (MW = 3500). The optimum preparation process of SeCS was determined by particle size analysis. The final solution was freeze-dried to preserve the bioactivity of SeCS.
