Surface characterization of plasma‐polymerized polyethylene glycol thin film modified by plasma treatment

Abstract

Polyethylene glycol (PEG) is a well‐known non‐fouling material used for protein adsorption and cellular adhesion. Recently, we successfully fabricated plasma‐polymerized PEG (PP‐PEG) thin films on various substrates by using a plasma enhanced chemical vapor deposition method and PEG200 as a precursor. The structure of our PP‐PEG thin film was found to be very similar to the chemical structure of a PEG polymer and also bore a non‐fouling characteristic for numerous proteins and cells without in vitro or in vivo toxicity. In this study, we modified this PP‐PEG thin film with a simple H2/He plasma treatment to change the non‐fouling surface property to a fouling one for proteins and cells. To make the patterned surfaces for proteins or cells on the protein‐ or cell‐resistant areas, depositing a new fouling PP thin film was unnecessary since it was possible to perform a simple H2/He plasma treatment through a metal shadow mask on the PP‐PEG thin film. Various surface analysis techniques such as water contact angle, atomic force microscopy, X‐ray photoelectron spectroscopy and time‐of‐flight secondary ion mass spectrometry were used to confirm the drastic changes in the surface chemical properties resulting from the plasma treatment. These results show that a PP‐PEG film, together with its plasma treatment through a shadow mask, is a very simple and useful patterning technique for various biological applications. Copyright © 2012 John Wiley & Sons, Ltd.