Table 4.
Zeta potentials and hydrodynamic diameters SiO2 NPs in skim milk and casein solutions at 25°C.
| Zeta potential (mV) | Hydrodynamic size (nm) | ||||||
|---|---|---|---|---|---|---|---|
| DW | Time | Skim milk (1 mg/ml) | Casein (0.35 mg/ml) | DW | Time | Skim milk (1 mg/ml) | Casein (0.35 mg/ml) |
| −28.2 ± 1.0A,a | 1 min | −27.3 ± 0.8AB,a | −43.9 ± 3.6C,b | 287.6 ± 1.7A,a | 1 min | 284.5 ± 4.7A,a | 317.87 ± 1.42B,b |
| 1 h | −27.1 ± 0.8AB,a | −36.0 ± 1.4B,b | 1 h | 322.0 ± 11.6C,b | 344.3 ± 18.5C,b | ||
| 24 h | −25.6 ± 1.3AB,a | −33.7 ± 0.7B,b | 24 h | 268.0 ± 9.2B,b | 292.0 ± 4.3A,a | ||
| 48 h | −25.4 ± 1.2B,b | −32.8 ± 2.4AB,c | 48 h | 270.6 ± 4.8B,b | 274.2 ± 1.8A,b | ||
| 7 d | −24.0 ± 1.9C,b | −32.4 ± 1.6A,c | 7 d | 296.6 ± 0.7A,b | 287.9 ± 1.6A,a | ||
Different letters (A–C) in the same column indicate significant differences between incubation times (p < 0.05). Different letters (a–c) in the same row indicate significant differences between skim milk and casein solutions (p < 0.05). Concentration of casein solution was adjusted to have an equivalent amount of protein content in 1 mg/ml of skim milk solution. Zeta potential and hydrodynamic radius of NPs in DW were measured in the absence of skim milk and casein solutions as a control.