Synthesis of Fe@C nanoparticles containing sulfo groups on their surfaces and study of their aggregation behavior in aqueous media

Magnetic iron nanoparticles (MNPs) encapsulated in a carbon shells and containing sulfo groups on the surface (Fe@C-SO3H) were synthesized. The aggregative stability of aqueous suspensions of the Fe@C-SO3H nanoparticles was studied in solutions of bovine serum albumin and calcium chloride and in phosphate-buffered saline, which simulate blood plasma. It is shown that the Fe@C-SO3H particles practically do not aggregate in the phosphate buffer saline for a long time (several days). On the contrary, MNPs encapsulated in a protein shells using ultrasonic treatment form aggregates up to 110–120 nm in size under these conditions. Suspensions of the Fe@C-SO3H particles are stable in aqueous solutions of calcium chloride in the range of the solid phase concentration between 0.05 and 0.10 g L−1. The results obtained indicate the possibility of using the functionalized Fe@C-SO3H nanoparticles in vitro experiments in biological media.