Potassium ferrocyanide anhydrous k4 fe cn 6

Citrate-coated PBNPs were synthesized by following the method published by Shokouhimehr and colleagues with some modifications [14 (link)]. Briefly, PBNPs were prepared by slowly adding 20 mL of 1.0 mM Fe(III) chloride anhydrous (FeCl₃; Sigma-Aldrich, Budapest, Hungary) solution with 0.5 mmol of citric acid (Sigma-Aldrich) to a solution containing an equimolar amount of potassium ferrocyanide anhydrous (K4[Fe(CN)6]; Sigma-Aldrich, Budapest, Hungary) under vigorous stirring for 15 min at 40 °C. The products were isolated with centrifugation at 21,130 rcf (Eppendorf 5424R centrifuge) at 4 °C.

A modified method of Shokouhimehr was used to prepare citrate-coated PBNPs [4 (link)]. Briefly, PBNPs were prepared by slowly adding 20 mL of a 1.0 mM Fe(III) chloride (anhydrous) (FeCl₃) (Sigma-Aldrich) solution containing 0.5 mmol of citric acid (Sigma-Aldrich) to a solution containing an equimolar amount of potassium ferrocyanide (anhydrous) (K₄[Fe(CN)₆]) (Sigma-Aldrich) under rigorous stirring at 40°C. Three samples (n = 3) were synthesized. The products were isolated by centrifugation at 29000 rpm (Beckman Ti 50.2 rotor, 30 min at 4°C) and then dialyzed for 3 × 1 hour (14 kDa filter) (Sigma-Aldrich, D9277).