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Making It Stick—Patterning on Teflon–like Surfaces

Poly(tetrafluoroethylene) (PTFE) is used extensively in medical devices. A major drawback of this material in some medical applications is the strong hydrophobicity of the PTFE surface. Instead of using complicated processes to chemically modify the surface properties of PTFE devices, a simple physisorption of poly(ethylene glycol) modified with fluorocarbon ends (Rf-PEGs) can be used to attach a biocompatible surface layer. Immersion of the PTFE substrate in a solution of Rf-PEG in ethanol (1 wt %), followed by immersion into water induces the stable adsorption of Rf-PEG onto PTFE. This physisorption makes the PTFE surface hydrophilic, and the stability of the adsorbed PEG layer under flow of water depends on the phase behavior and erosion rate of the bulk gel state of the Rf-PEG. PTFE treated with an Rf-PEG that is insoluble in water exhibits stable surface properties even in the presence of detergents. Patterned networks and arrays of gel layers are readily created as well (see figure). This new method provides a simple, economic way to modify the surface properties of PTFE-based devices for biomedicine and biotechnology.

For further information, please contact Professor David Tirrell, team leader of IRG 1: (626) 395-3140 or tirrell@cheme.caltech.edu.


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