Paper BI-ThP19
Exploring Critical Parameters in Biointerface Design using Plasma-Modified Polymers

Thursday, October 21, 2010, 6:00 pm, Room Southwest Exhibit Hall

The development of new transducing substrate materials, such as polymers, has spurred a growing interest in assessing the influences of surface topography and chemistry of the abiotic layer on the bio-functionality of the biotic layer. However, it is a challenge to differentiate the contributions of surface roughness and surface chemistry to biointerface functionality, as most surface modification methods tend to alter both at the same time. In this work, we discuss a dry and wet chemistry approach to biointerface development on polymeric substrates aimed at minimizing changes in the surface morphology. Specifically, an NRL developed electron beam-generated plasma processing system was used to functionalize the surface of polystyrene microtitre plates, which were then silanized to covalently immobilize biomolecules. Electron beam plasmas are unique in that they deliver high flux of low energy (< 5 eV) ions to substrate surfaces enabling selective, chemical alteration of the top few nanometers of any material without significant morphological modification. Thus, reactive hydroxyl groups, that make the characteristically inert material amenable to silane chemistry, can be introduced while maintaining substrate morphology. Silanization is an easy, controllable, and conformal covalent immobilization method that supports a wide variety of bio-immobilization schemes. Biomolecules covalently immobilized using this combined dry-wet chemistry approach retained functionality and demonstrated attachment efficiency comparable (and in some cases superior) to specialized commercial microtitre plates. We have used a combination of complementary surface analytical techniques to evaluate the relationships between the physical and chemical properties of the treated polymer surfaces, with particular emphasis on attachment of a functional silane layer, which is a critical parameter for efficient covalent bio-immobilization. Based on our results, we conclude that the development of novel interface materials with superior transducing capabilities is contingent on the deeper understanding of the complex physicochemical interactions between substrate polymer and the chemical/biological components attached to it.