MN was synthesized following a protocol published previously [22 (link)]. Briefly, 30ml of Dextan-T10 (0.3 g/ml, Pharmacosmos A/S, Holbaek, Denmark) was mixed with 1ml of FeCl3•6H2O (0.65 g/ml, Sigma, Saint Louis, MO) while flushing argon gas for an hour. One milliliter of FeCl2•4H2O (0.4 g/ml, Sigma) was added to the mixture and 15ml of cold NH4OH (28%, Sigma) was added dropwise to the stirred mixture. The temperature was increased to 85°C for 1 h to start the formation of a nanoparticle dispersion and then cooled to room temperature. The magnetic nanoparticles were concentrated to 20 ml using Amicon ultra centrifugal units (MWCO 30 kDa; Millipore, Darmstadt, Germany). The resulting dextran-coated magnetic nanoparticles were cross-linked by epichlorohydrin (14 ml, 8 h, Sigma) and aminated with subsequent addition of NH4OH (28%, 60 ml). Aminated magnetic nanoparticles (MN) were purified by dialysis and concentrated using Amicon ultra centrifugal units.
MN properties were as follows: iron concentration was 10.94 mg/ml as determined using Total Iron Reagent Set (Pointe Scientific, Canton, MI); each nanoparticle contained 74 amine groups as determined by the SPDP quantification method; the size of MN was 20.3±0.6 nm as determined by dynamic light scattering (Zetasizer Nano ZS, Malvern Instruments Ltd., Westborough, MA).
MN properties were as follows: iron concentration was 10.94 mg/ml as determined using Total Iron Reagent Set (Pointe Scientific, Canton, MI); each nanoparticle contained 74 amine groups as determined by the SPDP quantification method; the size of MN was 20.3±0.6 nm as determined by dynamic light scattering (Zetasizer Nano ZS, Malvern Instruments Ltd., Westborough, MA).
