Microspheres for Magnetic Separation of Proteins

Transcription

1 Supplementary Information for Preparation of Fe 3 O Double Hydroxide Core Shell Microspheres for Magnetic Separation of Proteins Mingfei Shao, Fanyu Ning, Jingwen Zhao, Min Wei,* David G. Evans, and Xue Duan State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing , P. R. China * Corresponding author. Tel: ; Fax: address: weimin@mail.buct.edu.cn Preparation of Fe 3 O (M= Co, Zn, Mg) microspheres Preparation of Fe 3 O microspheres: An in situ crystallization of a CoAl-LDH nanoplatelet shell on the surface of Fe 3 O microspheres was carried out. In a typical procedure, 0.01 mol of CoCl 2 6H 2 O and mol of NH 4 NO 3 were dissolved in deionized water to form a solution with a total volume of 70 ml. The Fe 3 O microspheres (0.1 g) were placed in the above solution in an autoclave at 100 C for 48 h. Finally, the resulting Fe 3 O microspheres were separated by a magnet, rinsed with ethanol and dried at room temperature. Preparation of Fe 3 O microspheres: The ZnAl-LDH microspheres were prepared by an in situ growth technique according to our previous report. 1 Zn(NO 3 ) 2 6H 2 O (0.01 mol) and NH 4 NO 3 (0.06 mol) were dissolved in deionized water (70 ml), and 1% ammonia solution was then slowly added until the ph reached 6.5. The S1

2 Fe 3 O microspheres (0.1 g) were immersed into the above solution in a glass vessel at 75 C for 36 h. Finally, the resulting Fe 3 O microspheres were separated by a magnet, rinsed with ethanol and dried at room temperature. Preparation of Fe 3 O microspheres: The MgAl-LDH shell was obtained on the surface of Fe 3 O microspheres by means of urea hydrolysis method similar to the previous report by our group. 2 A solution of Mg(NO 3 ) 2 6H 2 O (0.005 mol) and urea (0.04 mol) in 100 ml of deionized water was placed in a glass vessel. The as-prepared Fe 3 O microspheres (0.1 g) were immersed into the solution. The glass vessel was sealed and maintained at 80 C for 1 day. After cooling, the resulting Fe 3 O microspheres were separated by a magnet, rinsed with ethanol and dried at room temperature. Preparation of comparison samples Preparation of NiAl-LDH shell on the surface of Fe 3 O 2 without AlOOH coating. For comparison, the Fe 3 O microspheres were synthesized in the absence of AlOOH layer similar to the previous report. 3 In a typical procedure, 0.1 g of Fe 3 O 2 microspheres were dispersed into a 70 ml of deionized water containing Ni(NO 3 ) 2 6H 2 O (0.01 mol), Al(NO 3 ) 3 9H 2 O (0.005 mol) and urea (0.015 mol), sealed in an autoclave and heated at 120 C for 48 h. The resulting product was filtered, washed thoroughly with deionized water and anhydrous ethanol and subsequently dried at room temperature. Preparation of NiAl-LDH shell on the surface of Fe 3 O without SiO 2 coating. The Fe 3 O 4 microspheres were dispersed in the AlOOH primer sol for 1 h with vigorous agitation, followed by withdrawing the microspheres by a magnet and washing thoroughly with ethanol. S2

3 The resulting Fe 3 O microspheres were dried in air for 30 min. The whole process (dispersion, withdrawing, drying) was repeated 10 times. The Fe 3 O microspheres (0.1 g) were placed in a solution (70 ml) containing Ni(NO 3 ) 2 6H 2 O (0.01 mol) and NH 4 NO 3 (0.015 mol) in an autoclave at 100 C for 48 h. The resulting Fe 3 O microspheres were separated by a magnet, rinsed with ethanol and dried at room temperature. Figure S1. SEM image of the Fe 3 O microspheres. Figure S2. (A) The EDX spectrum of the Fe 3 O microspheres; (B) the corresponding elemental contents. S3

4 Figure S3. SEM images of (A) Fe 3 O (B) Fe 3 O and (C) Fe 3 O microspheres. Table S1. M(II)/Al ratio of the Fe 3 O (M=Ni, Co, Zn, Mg) microspheres Microspheres M(II)/Al ratio Fe 3 O Fe 3 O Fe 3 O Fe 3 O S4

5 Figure S4. (A) The NiAl-LDH material synthesized on the surface of Fe 3 O 2 particles without an AlOOH coating. (B) The Fe 3 O microspheres synthesized without a SiO 2 layer. Figure S5. FT-IR spectra of (a) Fe 3 O 4 particles, (b) Fe 3 O 2, (c) Fe 3 O and (d) Fe 3 O microspheres. The FT-IR spectrum of Fe 3 O microspheres (Figure S5, curve d) shows a new band at 2205 cm 1 due to the presence of cyanate (CNO ) anions in the interlayer region of NiAl-LDH. 4 S5

6 Figure S6. The N 2 -sorption isotherms and pore-size distribution (inset) of the Fe 3 O (M = Co, Zn, Mg) microspheres. Figure S7. Room temperature (300 K) magnetic hysteresis loops of Fe 3 O 4, Fe 3 O 2, Fe 3 O and Fe 3 O microspheres. S6

7 Scheme S1. A schematic representation of the magnetically recyclable protein separation process using Fe 3 O microspheres. Figure S8. XPS spectra in the (A) Al 2p and (B) Fe 2p regions for the Fe 3 O microspheres before (curve a) and after (curve b) reaction with His-tagged GFP. S7

8 Figure S9. Florescence intensity of the His-tagged GFP solution as a function of adsorption time using different types of LDH microspheres. Figure S10. Photographs of His-tagged GFP solutions after reaction for 30 min with different LDH microspheres. S8

9 Figure S11. Plots of binding capacities for His-tagged GFP of various LDH microspheres as a function of reaction time. Figure S12. The zeta potential distribution spectra for the Fe 3 O (M = Ni, Co, Zn, Mg) microspheres. In order to further study the effect of the charge density of different LDH microspheres, zeta potential analysis was carried out using photon correlation spectroscopy (PCS, Nano Granularity Analyzer Zetasizer-3000HS, Malvern Instruments). The zeta potential values were determined to be 26.0, 36.9, 24.2 and 17.0 mv for Fe 3 O Fe 3 O Fe 3 O and Fe 3 O S9

10 respectively (Figure S12). The results show the surface potential decreases in the order: Co/Al > Ni/Al > Zn/Al > Mg/Al, which is consistent with the elemental analysis results (Table S1). However, no correlation between adsorption capacity and surface potential can be found. Figure S13. (A) TEM and (B) SEM images of the Fe 3 O after five reaction cycles with His-tagged GFP solution. References: 1. Zhang, F. Z.; Zhao, L. L.; Chen, H. Y.; Xu, S. L.; Evans, D. G.; Duan, X. Angew. Chem. Int. Ed. 2008, 47, Lv, Z.; Zhang, F. Z.; Lei, X. X.; Yang, L.; Xu, S. L.; Duan, X. Chem. Eng. Sci. 2008, 63, Pan, D. K.; Zhang, H.; Fan, T.; Chen, J. G.; Duan X. Chem. Commun. 2011, 47, Shu, X.; Zhang, W. H.; He, J.; Gao, F. X.; Zhu Y. X. Solid State Sci. 2006, 8, S10