Mono-M2e formed particles whose hydrodynamic diameters have a distribution which peaks at 34.5 nm, while the distribution of Tetra-M2e peaks at 22.9 nm (Figure 2 ). It is also noteworthy that the size distribution peak of Mono-M2e is broader than that of Tetra-M2e, suggesting that the former has a higher degree of polydispersity.