Dynamic light scattering (DLS) was carried out using a Beckman Coulter DelsaMax Pro, measured at 22 • C, with samples dispersed in ultrapure water (1 mg mL -1 ). Transmission electron microscopy (TEM) was performed with a JEOL 2100 transmission electron microscope operated at 200 kV. Samples were prepared by depositing NPs dispersed in water (0.05 mg mL -1 ) onto a carbon coated 300 mesh copper grid (Agar Scientific). NP diameter and population were measured using ImageJ (version v1.53) with a sample size of approximately 300 NPs. By assuming the particles were spherical, the diameter was calculated by measuring the area of the particles, with an estimated resolution of 0.1 nm. This resolution was used as the bin width to produce a histogram of each population. It was then possible to determine the dispersity of the NPs using the concept of information entropy, as first introduced by Shannon, and modified to suit nanoparticle analysis as follows: