Surface analysis of protein-resistant, plasma-polymerized ethylene glycol thin films

Poly(ethylene glycol) (PEG) has been widely used in biomedical applications because of its protein-resistant and nontoxic properties. In this study, a plasma-polymerized ethylene glycol (PPEG) thin film was deposited on a substrate using a capacitively coupled plasma chemical vapour deposition (CCP-CVD) method with various plasma powers and ethylene glycol as a precursor. The surfaces of the PPEG thin films were characterized using time-of-flight secondary ion mass spectrometry (ToF-SIMS) along with a principal component analysis (PCA), and XPS. We confirmed that the PPEG thin film deposited at low plasma power closely resembles PEG polymers in terms of surface chemical composition and protein-resistant property. To make patterned surfaces with protein-resistant property for proteins, a PPEG thin film was first uniformly deposited on a glass slide and patterns were produced on the PPEG coated surface by depositing a plasma-polymerized amine film through a metal shadow mask. When we spotted proteins on the patterned surface, they were immobilized only onto the plasma-polymerized amine areas but not onto the PPEG areas. These results show that PPEG surfaces would be useful for the construction of various protein arrays.