Superparamagnetism, that is responsiveness to an applied magnetic field without permanent magnetization, is an especially important property therefore, these magnetic properties are critical in the applications of the biomedical and bioengineering fields. The magnetic response of Fe3O4 MNPs was tested by placing a magnet near the glass bottle. The black particles were attracted toward the magnet; therefore the Fe3O4 MNPs can be separated from the emulsion under an external magnetic field, as shown in Figure 11c.