Samples were prepared on 12-well plates by depositing on each well 1 mL of a GO dispersion diluted in Milli-Q water (Merck Millipore, UK) to a concentration of 20 μg/mL. After allowing the flakes to sediment for 24 hours at room temperature, the samples were observed using a PrimoVert inverted microscope (Carl Zeiss, UK) in bright-field at a magnification of 200x. Only micrometre-sized flakes were visible under the optical microscope, which resulted in the recording of images of l-GO only. Hundreds of flakes were manually measured on ImageJ by determining the longest Feret diameter in each object.