Nano zs dynamic

The zeta potential of the magnetite, the GO sheets and their pristine and reduced composite forms were determined in a Nano ZS dynamic light scattering (DLS) apparatus (Malvern Instruments, Malvern, Worcestershire, UK) with a 4 mW He-Ne laser source (λ = 633 nm). Disposable zeta cells (DTS 1070) (Malvern Instruments, Malvern, Worcestershire, UK) were used to record the electrophoretic mobilities at 25 ± 0.1 °C and the Smoluchowski equation was applied to calculate the zeta potentials. The accuracy of the measurements is ±5 mV, and the zeta-standard of Malvern (55 ± 5 mV) was used for calibration. The dispersions were diluted to give an optimal intensity of ~100 cps. The samples were homogenized in an ultrasonic bath for 10 s, after which 2 min relaxation was allowed before the measurements. The electrolyte concentration was kept at constant value (I = 10 mM).

The particle size and surface charge of freshly prepared and 10-days-stored filled hydrogels were analyzed by using a Nano ZS dynamic light scattering instrument (Malvern instruments Ltd., Worcestershire, UK) based on the method proposed by Hinderink, Schröder, Sagis, and Berton-Carabin [17 (link)].