N hydroxysuccinamide

Anhydrous iron (III) chloride (FeCl₃), iron (II) chloride tetrahydrate (FeCl₂·4H₂O) 99%, ammonium hydroxide (30–33% M), Tween-80, folic acid (FA), N,N′-carbonyldiimidazole (CDI), (1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC), and N-hydroxysuccinamide (NHS) were purchased from Sigma-Aldrich. Oleic acid and sodium citrate were purchased from TCI chemicals. 5-Fluorouracil and curcumin were purchased from MOLchem. Nitrogen-purged Mili-Q was used in all the steps involved in the synthesis and formulation of magnetic nanoparticles.

First, 500 mg of MS-Cu-1 nanospheres were dispersed in 40 mL of ethanol. Then, 5 mL of 3-aminopropyl triethoxysilane (FUJIFILM Wako Pure Chemical Corporation, Minato City, Japan) was added and stirred at 25 °C for 1 d in the dark. The products were collected by centrifugation, then washed with ethanol twice. The collected nanospheres were dispersed in 40 mL of 2-(N-morpholino)ethanesulfonic acid monohydrate solution (0.1 mol/L, pH = 5.5, FUJIFILM Wako Pure Chemical Corporation, Minato City, Japan). Then, 65.92 mg of 1-[3-(dimethylamino)propyl]-3-ethylcarbodiimide hydrochloride (Sigma Aldrich, St. Louis, MO, USA), 36.83 mg of N-hydroxysuccinamide (Sigma Aldrich, St. Louis, MO, USA), and 146.4 mg of PEG acid disulfide (Polypure, MW = 915.1) were added slowly and stirred at room temperature for 12 h. The products were collected by centrifugation, washed with ultrapure water twice, and freeze-dried to prepare the PEG-MS-Cu nanospheres.