How Bound and Free Fatty Acids in Cellulose Films Impact Nonspecific Protein Adsorption

Publication year: 2017
Authors: Niegelhell K. a, Suessenbacher M. b, Sattelkow J. c, Plank H. c, Wang Y. d, Zhang K. d, Spirk S. a

a - Graz University of Technology, Institute for Paper, Pulp and Fiber Technology, Inffeldgasse 23, 8010 Graz, Austria
b - Graz University of Technology, Institute for Chemistry and Technology of Materials, Stremayrgasse 9, 8010 Graz, Austria
c - Graz University of Technology, Institute for Electron Microscopy and Nanoanalysis, Steyrergasse 17, 8010 Graz, Austria
d - Georg-August-University of Goettingen, Wood Technology and Wood Chemistry, Büsgenweg 4, 37077 Göttingen, Germany

Published in: Biomacromolecules, 2017, Vol. 18 (12), p. 4224–4231
doi: 10.1021/acs.biomac.7b01260

The effect of fatty acids and fatty acid esters to impair nonspecific protein adsorption on cellulose thin films is investigated. Thin films are prepared by blending trimethylsilyl cellulose solutions with either cellulose stearoyl ester or stearic acid at various ratios. After film formation by spin coating, the trimethylsilyl cellulose fraction of the films is converted to cellulose by exposure to HCl vapors. The morphologies and surface roughness of the blends were examined by atomic force microscopy revealing different feature shapes and sizes depending on the blend ratios. Nonspecific protein adsorption at the example of bovine serum albumin towards the blend thin films was tested by means of surface plasmon resonance spectroscopy in real-time. Incorporation of stearic acid into the cellulose leads to highly protein repellent surfaces regardless of the amount added. The stearic acid acts as a sacrificial compound that builds a complex with bovine serum albumin thereby inhibiting protein adsorption. For the blends where stearoyl ester is added to the cellulose films, the cellulose:cellulose stearoyl ester ratios of 3:1 and 1:1 lead to much lower nonspecific protein adsorption compared to pure cellulose, whereas for the other ratios, adsorption increases. Supplementary results were obtained from atomic force microscopy experiments performed in liquid during exposure to protein solution and surface free energy determinations.

MP-SPR keywords: AFM, bound mass, BSA, cellulose film, functionalized cellulose, inhibition of protein adsorption, nanocellulose, protein adsorption, stearic acid