Dynamic Cellular Adhesion Mediated by Copolymeric Nanofilm Substrates

Amphiphilic block copolymers are finding increased potential in biological and medical research due to their innate alternating hydrophilic and hydrophilic blocks/segments which can be used to package therapeutics, or coat a broad array of biological interfaces. Some studies are already directed towards utilizing these copolymers' ability to form micelles or vesicles to develop novel methods of drug delivery to prevent inflammation or pro-cancer activity. Our study, however, aims to investigate the more fundamental cell-block copolymer interaction for use in protective nanofilms to prevent bio-fouling of non-tissue based implantable devices. Block copolymers could potentially fill the demand for biologically inert, highly functionalizable biomaterials desirable for this type of application. Two such polymers used in our study include PMOXA-PDMS-PMOXA triblock copolymer and PEO/PMMA diblock copolymer. Each block copolymer possesses hydrophilic and hydrophobic blocks that enable it to mimic the cell lipid membrane. So far we have shown that triblock copolymer is capable of inhibiting the accumulation of murine macrophages onto glass substrates. Preliminary evidence has suggested that the triblock copolymer has anti-adsorptive as well as non-inflammatory capabilities during short incubation periods (7 days) in vitro. While the diblock copolymer displays minimal anti-adsorptive activities, nanofilms comprised of a mixture of the two copolymers were able to significantly reduce macrophage accumulation onto glass substrates. The disparate behavior seen by macrophages on the different materials may be due to specific inherent properties such as preference for hydrophobic vs. hydrophilic surfaces and/or rough vs. smooth nano-textures. Furthermore, the specific end groups of the two polymers may exhibit varying capacities to resisting non-specific protein adsorption. Continued investigation outlining the physical and chemical properties desirable for an anti-adsorptive nano-film coating will serve as a basis upon which to design durable implant-tissue interfaces that can react to various external stimuli.