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ARS Home » Midwest Area » Peoria, Illinois » National Center for Agricultural Utilization Research » Plant Polymer Research » Research » Publications at this Location » Publication #217143
Title: Effect of polymer surface modification on polymer-protein interaction via hydrophilic polymer grafting

Author
item Liu, Sean
item KIM, JUN-TAE - CORNELL UNIVERISITY
item Kim, Sanghoon

Submitted to: Journal of Food Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/18/2008
Publication Date: 4/1/2008
Citation: Liu, S.X., Kim, J., Kim, S. 2008. Effect of polymer surface modification on polymer-protein interaction via hydrophilic polymer grafting. Journal of Food Science. 73(3):E143-E150.

Interpretive Summary: To reduce membrane fouling caused by protein adsorption on hydrophobic polyethersulfone (PES) membranes, we investigated polymer grafting as a technique of making PES surface more hydrophilic. Hydrophilic polymers, i.e., poly(vinyl alcohol) (PVA), polyethylene glycol (PEG), and chitosan were used to graft onto PES membrane surfaces after UV/ozone treatment of PES surface because of their excellent hydrophilic property. Instrument techniques such as contact angle measurement, Fourier transform infrared spectroscopy (FTIR), and atomic force microscopy (AFM) were used to determine the results of hydrophilic polymer grafting onto the PES membranes; the data from the instrument measurements indicated that PES membranes were successfully modified by grafting of the hydrophilic polymers. The static protein adsorption experiments with the modified PES membranes showed that increase in hydrophilicity of modified PES membranes resulted in lower protein adsorption by 20 - 60% comparing to the virgin PES membrane. Among three hydrophilic polymers studied, PEG showed the most favorable result in terms of contact angle and protein adsorption. These results will benefit the development of new membranes used for economically extracting high-valued zein from dried distillers grains (DDG), by-products of biofuel production.

Technical Abstract: Surface modification of flat sheet ultrafiltration membranes, polyethersulfone (PES) was investigated to improve the hydrophilicity of the membrane surface thereby reducing adsorption of the proteins onto the membrane. Grafting of hydrophilic polymers onto UV/ozone treated PES was used to improve the hydrophilicity of the commercial PES membranes. Hydrophilic polymers, i.e., poly(vinyl alcohol) (PVA), polyethylene glycol (PEG), and chitosan were employed to graft onto PES membrane surfaces because of their excellent hydrophilic property. The surfaces of modified PES membranes were characterized by contact angle measurement, FTIR, and AFM. The FTIR spectra indicated that PES membranes were successfully modified by grafting of the hydrophilic polymers. The modified PES membranes showed 20 - 50% reduction in contact angle measurements in comparison with those of the virgin PES membrane. Tapping mode AFM technique was employed to investigate the changes of surface topography, cross section, and root mean square roughness of the modified PES membrane surfaces. The modified PES membranes showed elevated roughness (ranging from 7.0 - 25.7 nm) than that of the virgin PES membrane (2.1 nm). It is concluded that grafting of PVA, PEG, and chitosan onto UV/ozone treated PES membranes increases hydrophilicity and lower protein adsorption by 20 - 60% comparing to the virgin PES membrane. Among three hydrophilic polymers studied, PEG showed the most favorable result in terms of contact angle and protein adsorption.