Gravity stop-flow electrophoresis: A high-power technique for size-based separation of graphene oxide nanosheets.

Graphene oxide (GO) exhibits size-dependent properties that enable its use in a range of applications. Current techniques for size-based separation of GO face several notable limitations and challenges. The gravity stop-flow electrophoresis (GSFE) technique is introduced here, for the first time, which addresses a large part of the stated limitations. Characterization methods were applied to each collected fractions for further correlation between size of each fraction and their corresponding properties. Characterization experiments including, a) the UV-Vis spectroscopy (Stokes shift from 195.4 nm for the smallest particle to 200.7 nm for the largest particle), b) capillary electrophoresis (migration time changed from 6.8 min for the smallest particle to 5 min for the largest particle), c) zeta potential measurement (changed from 23.3 mV for the largest particle to 37.7 mV for the smallest particle), d) electrophoretic mobility (determined by dynamic light scattering, changed from 2.9 × 10-8 m2V-1s-1 for the smallest particle to 1.8 × 10-8 m2V-1s-1 for the largest particle) and e) transmission electron microscopy for the smallest and the largest particles were performed. Furthermore, the results demonstrated that this technique has a high resolution with less limitations when compared to most classical separation methods. Finally, the most important limitation of capillary electrophoresis was resolved by significantly improving the throughput of separation.