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  • br Experimental section br Chemicals and materials

    2019-10-14


    2. Experimental section
    2.1. Chemicals and materials
    Ferric chloride hexahydrate (FeCl3•6H2O, 99%) was purchased from Tianjin Guangfu Technology Development CO., Ltd. Cyclohexane (C6H12, 99%), hexane (C6H2, 98%), and ethanol were obtained from Tianjin Fuyu Fine Chemical CO., Ltdj. Oleic Belinostat (PXD101) (OA, AR) and sodium
    oleate (AR) were purchased from Sinopharm Chemical Reagent CO., Ltd. 1-Octadecene (OD, 90%), tetramethyl orthosilicate (TMOS, 98%), Igepal CO-520 [polyoxyethylene(5) nonylphenylether], and HAuCl4•4H2O were purchased from Aladdin Industrial Corporation. (3-aminopropyl) triethoxysilane (APTES, 98%) was purchased from Shanghai Bu Bai Chemical Technology Co., Ltd.
    2.2. Synthesis of iron-oleic precursor
    5.4 g FeCl3•6H2O and 18.25 g sodium oleate were dissolved in a mixture of 30 mL deionized water, 70 mL hexane and 40 mL ethanol, stirring at 70 °C for 4 h. The mixture was separated to obtain an oil phase liquid and washed with deionized water for several times, then evaporating at 80 °C to obtain brown-red waxy solid.
    2.3. Synthesis of Fe3O4 nanoparticles
    7.2 g iron-oleic precursor was added into mixture of 38 mL OD and 3.6 mL OA, and stirred under argon flow at room temperature. After 30 min, the mixture was heated up to 100 °C for 30 min, then the so-lution was heated up to 320 °C for 40 min. During the heating, argon gas was gently blown through the reaction system to remove the trace hydrate vapor. After cooling to room temperature, the obtained product was precipitated by centrifuge and washed with ethanol. Then cyclo-hexane was added to precipitate and centrifuged to get solution. Ethanol was added to above solution, and the final Fe3O4 nanoparticles were obtained by centrifuge. The as-prepared Fe3O4 nanoparticles were dispersed in hexane.
    0.5 mL Igepal CO-520 and 0.08 mL NH4OH (25%) were injected into 2 mL Fe3O4 hexane solution. Belinostat (PXD101) The mixture was sonicated at room tem-perature for 30 min. Then 60 μL TMOS was dropwise added and the mixture was vigorously stirred at room temperature for 48 h. Finally, 20 μL APTES was added into the reaction system and stirred for another 18 h. [email protected] and [email protected] nanoparticles were obtained by centrifugation, and washed with ethanol and water for several times.
    30 mL of 0.7 mmol/L HAuCl4•4H2O aqueous solution was added into [email protected] and mixture was stirred at 60 °C for 1 h. Then the resulting nanoparticles were collected by centrifuging, washed with water and dried at 80 °C. After calcination at 150 °C for 2 h, the final product was obtained and labeled as FeSiAuO.
    2.6. Synthesis of FeSiAuO-DOX and FeSiAuO-DOX-PEG
    30 mg FeSiAuO was added to 5 mL phosphate buffer solution con-taining 2.5 mg DOX (1 mg/mL) and stirred for 24 h at room tempera-ture in the dark, the product obtained after centrifugation is named FeSiAuO-DOX. Then, the loading process of DOX was repeated, after stirred for 24 h, the PEG−COOH (20 mg), EDC (8 mg) and NHS (6 mg) were added above solution and stirred for further 2 h. The sample was separated by centrifuge, and washed several times with PBS. FeSiAuO-DOX-PEG was obtained after drying.
    2.7. Characterization
    Power X-ray diffraction (XRD) patterns were achieved from a Rigaku D/max TTR- III diffractometer with Cu Kα radiation (λ = 0.15405 nm). Transmission electron microscopy (TEM) images were taken on a JEM-2100 system at an accelerating voltage of 200 kV. Fouriertransform infrared spectra (FT-IR) were performed by a Thermo Nicolet iS50 FT-IR Spectrometer over a potassium bromide pellet, and
    the diffuse reflectance spectra were scanned over the range from 400 cm−1 to 4000 cm−1. The UV–vis spectra were recorded by UV-1901 spectrophotometer. Potential was measured using Malvern zetasizer instrument (ZEN3690, Malvern, UK).
    2.8. Drug loading and controlled release
    In order to determine the specific DOX release by absorbance value, the DOX calibration curve needs to be drawn. The specific experiment is as follows: weigh 4 mg DOX and add PBS buffer solution to 50 mL standard solution and dilute it to 1, 2, 5, 10, 20, 40 and 80 μg/mL. Then, their absorbance values were measured respectively.