Hydrophobic SPION NPs were prepared using a thermal decomposition method in accordance with the literature. FeCl 3 • 6 H 2 O (0.54 g, 2 mmol) was dissolved in water (6 mL, 333 mmol), ethanol (8 mL, 137 mmol), and hexane (14 mL, 106 mmol) at room temperature. Oleic acid (1.9 mL, 6 mmol) was added to the solution and stirred for 30 minutes. Sodium hydroxide (0.24 g, 6 mmol) was added to the stirred solution and sealed in a closed vessel and heated to 70 • C for 4 hours. The resulting solution was cooled to room temperature, forming two distinct layers. The top organic layer, containing Fe(oleate) 3 , was separated, collected and washed with ultrapure water three times. To remove hexane, Fe(oleate) 3 was heated in a vacuum oven at 80 • C overnight. The dried Fe(oleate) 3 precursor was resuspended in oleic acid (0.32 mL, 1 mmol) and 1-octadecane (12.5 mL, 38 mmol) in a sealed vessel and oxygen was degassed with N 2 gas for 1 hour at room temperature. Subsequently, the solution was heated at 320 • C for 30 minutes under the inert atmosphere in a sealed vessel. The solution was cooled to room temperature, and excess ethanol was added to precipitate NPs. Hydrophobic SPIONs were collected by centrifugation and the supernatant decanted. The isolated solid was re-dispersed in hexane (approx. 1-2 mL) and subsequently precipitated in excess ethanol. This precipitation-re-dispersion process was repeated three times to purify the magnetic NPs. The SPIONs were stored in cyclohexane (5.0 mg/mL).