Modification of the hydrophilic/hydrophobic characteristic of zein film surfaces by contact with oxygen plasma treated PDMS and oleic acid content.
Zein has been widely studied as a biopolymer due to its unique film-forming abilities. Surface properties are of high importance for certain applications which include microfluidics and tissue engineering, as they drastically affect the end result. It is important to develop techniques to modify zein surface properties without compromising bulk material properties. In this study, we developed a facile technique to change the water affinity of zein film surfaces, compatible with patterning techniques via soft lithography. This is achieved by a simple solvent casting technique onto a polydimethylsilohexane (PDMS) substrate that was exposed to oxygen plasma. Water contact angle measurements (WCA) were used to assess the hydrophillicity of zein surfaces and they reached as low as 20°. Atomic force microscopy, optical absorbance and light microscopy were used to study the characteristics of the film and its surface topography. Hydrophilic zein surfaces had higher roughness values compared to hydrophobic ones. Surface roughness, introduced by sandpaper and gratings does not have the same effect as surface chemistry. The amphiphilic nature of plasticizer oleic acid also contributed to the change in the water contact angle of the films. In conclusion, we demonstrated that zein film's surface properties can be controlled by its ability to self-assemble depending on the substrate that it is being cast on.
Department of Food Science and Human Nutrition, University of Illinois Urbana-Champaign, 1304 W. Pennsylvania Ave, Urbana, USA.
P Gizem
PG
Gezer
Department of Agricultural and Biological Engineering, University of Illinois Urbana-Champaign, 1304 W. Pennsylvania Ave, Urbana, USA.
Serena
S
Brodsky
Department of Bioengineering, University of Illinois Urbana-Champaign, 1304 West Springfield Avenue, Urbana, USA.
Austin
A
Hsiao
Department of Electrical and Computer Engineering, University of Illinois at Urbana-Champaign, 1406 W. Green St, Urbana, USA; Micro and Nanotechnology Laboratory, University of Illinois at Urbana-Champaign, 208 North Wright Street, Urbana, USA.
G Logan
GL
Liu
Department of Food Science and Human Nutrition, University of Illinois Urbana-Champaign, 1304 W. Pennsylvania Ave, Urbana, USA; Department of Food Science, Purdue University, 745 Agricultural Mall drive, West Lafayette, IN 47907, USA. Electronic address: jkokini@purdue.edu.
Jozef L
JL
Kokini
D004129:Dimethylpolysiloxanes / Q000737:chemistry*; D057927:Hydrophobic and Hydrophilic Interactions; D018625:Microscopy, Atomic Force; D019301:Oleic Acid / Q000737:chemistry*; D010100:Oxygen / Q000737:chemistry*; D010968:Plasticizers / Q000737:chemistry; D013499:Surface Properties; D015028:Zein / Q000737:chemistry*
D004129:Dimethylpolysiloxanes; D010968:Plasticizers; D019301:Oleic Acid; C013830:baysilon; D015028:Zein; D010100:Oxygen
Films; Hydrophobicity; Surface; Zein