Synthesis of Lauric Acid-Coated Magnetite Nanoparticles

Lauric acid-coated magnetite nanoparticles were synthesized by coprecipitation and subsequent in situ coating with lauric acid, a variation of the process described by Bica et al.12 Briefly, Fe (II) and Fe (III) salts (1.988 g of FeCl₂·4H₂O and 5.406 g of FeCl₃·6H₂O) were dissolved in 20 mL of Millipore water (Merck Millipore, Billerica, MA, USA) and stirred at 80°C under an argon atmosphere. Under vigorous stirring, 20 mL of NH₃ solution (23%) was then added. Immediately, the solution was heated to 90°C and 1.25 g lauric acid, dissolved in acetone, was added. The blackish precipitate quickly formed a colloidal, brownish suspension, which was left to homogenize for 30 minutes at 90°C. The fluid was then placed inside a dialysis tube with a MWCO of 8 kDa and dialyzed multiple times. The so-prepared suspension was still colloidally stable and was diluted to 100 mL with Millipore water.