Complexes of Magnetic Nanoparticles with Cellulose. Nanocrystals as Regenerable, Highly Efficient, and Selective. Platform for Protein Separation. Jiaqi Guo,.
Supporting information
Complexes of Magnetic Nanoparticles with Cellulose Nanocrystals as Regenerable, Highly Efficient, and Selective Platform for Protein Separation Jiaqi Guo,† Ilari Filpponen,†,ǂ* Leena-Sisko Johansson,† Pezhman Mohammadi,† Mika Latikka,§ Markus B. Linder,† Robin H. A. Ras,§ Orlando J. Rojas†,∥, §
†
Department of Bioproducts and Biosystems, School of Chemical Engineering, Aalto University,
FI-00076 Aalto, Finland ǂ
Alabama Center for Paper and Bioresource Engineering, Department of Chemical Engineering,
Auburn University, Auburn, AL 36849-5127, United States §
∥
Department of Applied Physics, School of Science, Aalto University, FI-00076 Aalto, Finland Departments of Forest Biomaterials and Chemical and Bimolecular Engineering, North
Carolina State University, Raleigh, NC 27695, United States
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1. Protein concentration analysis The overall concentration of lysozyme was analyzed with a Shimadzu UV-2550 spectrophotometer (Shimadzu Corporation, Kyoto, Japan) at the wavelength of 280 nm.1 The calculation of lysozyme concentration followed by Beer-Lambert's law 𝑐=
A ∗ 14307 ε∗b
where: A = absorbance ε = the extinction coefficient, 36000 for lysozyme b = the path length, 1 cm c = the concentration, g/L 14307 = the molecular weight of lysozyme
2. SDS-PAGE analysis of lysozyme SDS-PAGE was performed under reduced conditions. Briefly, sample buffer prepared with 10% w/v SDS, 10 mM beta-mercapto-ethanol, 20 % v/v Glycerol, 0.2 M Tris-HCl pH 6.8 and 0.05% w/v Bromophenol blue. Protein samples were heated with sample buffer for 3 min at 90 ̊C and loaded on Mini-PROTEAN® Tris/Tricine gels (Bio-Rad). Electrophoresis was done using MiniProtein Tetra cell electrophoresis system (Bio-Rad). Gels were stained with Coomassie Brilliant Blue R (Sigma). After the distaining, gel pictures were taken using Gel Doc™ XR Bio-rad System and Image Lab™ (Biorad) was used to analyze the digital images. Protein concentrations were then calculated by converting the density of protein bands in the gel picture with Image Lab™ sodtware and also absorbance at 280 nm using BioTek’s Cytation™3 system.
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3. Characterization of TEMPO-oxidized cellulose nanocrystals (TEMPO-CNC). 3.1 Calculation of degree of oxidation Calculation of degree of oxidation (DO)2 DO≈
I(1730 cm−1) I(1050 cm−1)
=
0.35 0.92
= 0.2
3.2 Transmission electron microscopy (TEM) characterization
Figure S1. TEM image of TEMPO-CNC.
4. Characterization of Fe3O4 NPs.
Figure S2. The mean size and size distribution of synthesized Fe3O4 nanoparticles. S-3
4.1 Stability test of NH2-Fe3O4 NPs and OA-Fe3O4 NPs
Figure S3. Stability of NH2-Fe3O4 NPs (in polar solvent, water) (Left) and OA-Fe3O4 NPs (in nonpolar solvent, toluene) (Right) after storing three months.
Figure S4. DLS graphs of Fe3O4 nanoparticles dispersed in toluene or water after storage of two months. Results indicate that nanoparticles remain stable in the dispersion.
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4.2 Zeta-potential characterization of NH2-Fe3O4 NPs.
Figure S5. Zeta-potential of synthesized NH2-Fe3O4 showing the positively charged surface.
5. Standard curve of copper ions analysis The amount of complexed copper ions was determined by measuring UV-vis absorbance of EDTA-Cu complex according to the method outlined by Kubota.3
Figure S6. Copper ions standard curve for calculation of complexed copper ions onto Fe3O4@CNC hybrids. S-5
REFERENCES 1.
Grimsley, R.G.; Pace, C.N. Spectrophotometric Determination of Protein Concentration. Curr. Protoc. Protein Sci. 2004, DOI: 10.1002/0471140864.ps0301s33.
2. Habibi, Y.; Chanzy, H.; Vignon, M. R. TEMPO-Mediated Surface Oxidation of Cellulose Whiskers. Cellulose 2006, 13, 679-687. 3.
Kubota, N.; Nakagawa, Y.; Eguchi, Y. Recovery of Serum Proteins Using Cellulosic Affinity Membrane Modified by Immobilization of Cu2+ Ion. J. Appl. Polym. Sci. 1996, 62, 1153-1160.
Superlink: Video S1: Magnetic collection of Fe3O4@CNC hybrids mixed with Lysozyme.
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