Figure 4.
The data produced for the sample in Fig. 3 were taken for 12 other samples. Each sample had six glycerol concentrations as well as pure PBS (0% glycerol). All 72 relaxation times calculated from the MSB measures are plotted as a function of the relaxation time calculated from the glycerol concentrations. The RMS error was 2.51% and the correlation coefficient was 0.9972 with very high significance (P-value was zero to machine accuracy) supporting the linear relationship between the MSB relaxation times and the ones calculated based on glycerol concentration. The reproducibility estimated from repeated measurements of an identical NP sample in buffer averaged 1.25%. The reference relaxation time of NPs in PBS was based on temperature of 20 °C, viscosity of water at that temperature of 1.0019 mPa·s (Ref. 27), and effective NP diameter of 113 nm.