Paper BI-TuP9
Effect of Film Fabrication Method on the Protein Fouling Resistance of Mixed Oligo(ethylene glycol) Films

Tuesday, October 21, 2008, 6:30 pm, Room Hall D

A major concern in the design of biosensors for studying protein interactions is protein fouling, or non-specific binding, which masks the signal from the binding event of interest. Mixed oligo(ethylene glycol) (OEG) films have become a standard surface coating used to avoid fouling of gold sensor surfaces. Such films comprise a probe coupling OEG (A) and a diluent of protein resistant OEG (B). Two methods exist for the fabrication of such surfaces: co-deposition of A and B, and sequential deposition, where A is inserted into a pre-existing monolayer of B. Though films fabricated by sequential deposition display better fouling resistance, the source of this resistance is unclear. It has been hypothesized that the improved fouling resistance is due to an absence of islanding in the film, however it could simply result from an extremely low A content. In order to identify the affect of the fabrication method, films prepared by both approaches must contain the same amount of A. Since few techniques exist which can accurately measure low amounts of A attached to a surface, the amount of probe which covalently couples to a film was used to evaluate the film’s A content. Using this technique, the fabrication conditions for both methods were adjusted to produce films containing the same amount of A. The extent of fibrinogen fouling on these now comparable films was measured with surface plasmon resonance imaging to evaluate if the actual fabrication method affects a film’s fouling resistance. Furthermore, electrochemically induced reductive desorption was used to indicate any presence of islanding and to evaluate film stability.