Malvern nano zs90 zetasizer nano

The morphology of the Fe₃O₄ nanoparticles were examined using a H-700H transmission electron microscope (TEM, Hitachi, Ltd., Tokyo, Japan) at an accelerating voltage of 100 kV, and the samples of Fe₃O₄ nanoparticles for the TEM study were prepared by placing drops of the nanoparticles in ethanol on the surface of carbon grids. The size of Fe₃O₄ nanoparticles was assessed by dynamic light scattering (DLS) using a DynaPro-MS800 instrument (Wyatt Technology, Santa Barbara, CA, USA), for which the Fe₃O₄ nanoparticles were dispersed in phosphate-buffered saline (PBS) at a concentration of 50 μg/mL. After ultrasonication, the aqueous solution was obtained after the samples were equilibrated at 25 °C for 10 min. The surface zeta potential of Fe₃O₄ nanoparticles was measured using a Malvern Nano-ZS90 Zetasizer Nano instrument (Malvern Instruments Ltd., Malvern, UK) at room temperature. The magnetic properties of the Fe₃O₄ nanoparticles were measured with a vibrating sample magnetometer (VSM, Quantum Design, Inc., San Diego, CA, USA) vibrating sample magnetometer at room temperature.

Fe₃O₄ NPs were synthesized by chemical co-precipitation of Fe²⁺ and Fe³⁺ ions with a molar ratio of 1:2 as follows. First, FeCl₃·6H₂O (3.60 g) and FeCl₂·4H₂O (1.33 g) were dissolved in deionized water (50 mL) at 70 °C under continuous nitrogen (N₂) flow and vigorous stirring. Second, NH₃·H₂O (15 mL) was added into the solution dropwise to react until the color of the sample turned to black, and the sample was further kept for 120 min to complete the reaction. Finally, Fe₃O₄ NPs were separated from the suspension solution by a magnet, washed with water and ethanol for three times, and dried in an oven at 80 ^oC overnight. The morphology of Fe₃O₄ NPs was characterized by transmission electron microscopy (TEM, Hitachi, Ltd., Tokyo, Japan). A DynaPro-MS800 instrument (Wyatt Technology, Santa Barbara, CA, USA) was used to determine the size of the NPs. Zeta potential measurement was performed with a Malvern Nano-ZS90 Zetasizer Nano instrument (Malvern Instruments Ltd., Malvern, UK). The magnetic properties were measured on a vibrating magnetometer (VSM, Quantum Design, Inc., San Diego, CA, USA).