The third step comprised attachment of either PEI or PHMBG chains. Thus, FeCl3·6H20 (7.58g, 28mmol) and FeCl2·4H2O (2.78g, 14mmol) were dissolved in 25mL DI water and the solution was brought to 80°C under nitrogen purge within ~30min. The solution was poured into 25mL of 30% NH4OH and the ensued black precipitate was stirred and kept at 80°C for 1h. The resulting particle suspension was sonicated for 1min and separated from supernatant by magnetocollection. Inhibitors,research,lifescience,medical The particles were then placed into a tube containing 30mL of 0.33M click here aqueous solution of TMAOH. The suspension was observed to be stable. The suspension

was separated by magnetocollection and washed twice with 50mL of deionized water. The resulting TMAOH-stabilized magnetite suspension (~25mL) was diluted

with (in) 40mL ethanol. To the resulting suspension, 3.6mL (16mmol) of TEOS were added and the suspension was sonicated for 5min, followed by addition of 4.6mL (20mmol) of GPTMS. Inhibitors,research,lifescience,medical The suspension was kept under vigorous shaking at room temperature for 48 hours and the particles were separated using magnetocollection, dialyzed (MWCO 12–14kDa) against an excess of deionized water overnight, snap frozen, and lyophilized. The resulting epoxy-modified particles designated M/SiO2 were characterized by FTIR and TGA. Elemental analysis were found (%):C, 17.0; Fe, 24.1; N, 0.04. The M/SiO2 particles were stored at −20°C Inhibitors,research,lifescience,medical prior to use. Core-Shell Particle Inhibitors,research,lifescience,medical Modified with PHMBG (PHMBG-M/SiO2). Particles designated PHMBG-M/SiO2 were synthesized using

10mL of the aqueous M/SiO2 particle suspension (magnetite content, ~0.5g), to which a solution of 0.9g of PHMBG in 500mL of deionized water was added. The mixture was sonicated for 5min and kept at 80°C for 16h followed by shaking at 250rpm at room Inhibitors,research,lifescience,medical temperature for 2 days, followed by dialysis against deionized water (MWCO, 12–14kDa) and drying by lyophilization. The resulting particles were characterized by elemental analysis, TEM, DLS, SQUID, and TGA. Elemental analysis, found (%):C, 27.8; H, 5.83; Fe, 18.3; N, 19.7. Core-shell particles modified with PEI (PEI- M/SiO2) were during synthesized as follows. To the TMAOH-stabilized magnetite suspension (~25mL) prepared as described above, 40mL of absolute ethanol were added and the diluted suspension was sonicated for 1min. To the resulting suspension, 3.6mL (16mmol) of TEOS were added and the suspension was sonicated for 5min, followed by addition of 4.6mL (20mmol) of GPTMS. The suspension was shaken (200rpm) at room temperature for 1h, aqueous solution of PEI (5g in 100mL water) was added, and the resulting mixture was shaken at room temperature for 1h, kept at 80°C for 1h and then shaken at room temperature for 16h. The suspension was then dialyzed (membrane MWCO, 12–14kDa) against excess deionized water. The resulting suspension did not exhibit any visible sedimentation of particles for several days at rest.