(577g) Patterned Chemical Vapor Deposition Polymerization of Functionalized Poly-P-Xylylene for Spatial Control of Protein Adsorption and Cell Adhesion
Recent advances in surface engineering technologies as applied to implantable biomedical devices can promote desirable, controllable host response including tissue integration. In particular, vapor-based polymer coatings have shown promise due to their processability and good biocompatibility. For example, parylene-type vapor-deposited polymers have been approved by the regulatory agencies for use with drug-eluting stents. While these vapor-deposited polymer provide appropriate biocompatibility, they are not functionalized and do not possess anchoring chemical groups that enable modifications. As such, these coatings are not conducive to immobilization of biomolecules or incorporation of functionality including resistance to protein adsorption. We have recently established a chemical vapor deposition (CVD) polymerization technique of substituted [2,2]paracyclophanes. Introduction of substituted paracyclophanes yields functionalized poly-p-xylylene coatings with a wide range of functional groups such as esters, amines, and alcohols that can covalently bind biomolecules. Moreover, the CVD polymerization technique offers a method in which the composition and the film thickness can be controlled with high accuracy, and produce excellent film adhesion to the substrate. In addition to obviating the need for solvents, initiators, or catalysts, and as a result minimize contaminations, CVD polymerization procedure is also amenable to further surface modification via other polymerization techniques. Using the CVD polymerization process, we have prepared patterned surfaces coated a photodefinable poly-p-xylylene, poly[4-benzoyl-p-xylylene-co-p-xylylene]. Illumination with light of 360 nm wavelengths will result in spatially-directed binding of molecules adjunct to the reactive coating. For instance, fluorescent model proteins were selectively adsorbed on this photodefinable coating. The proteins effectively adsorbed on the coated surface in a pattern, as established by the CVD coating of poly[4-benzoyl-p-xylylene-co-p-xylylene]. The immobilization of extracellular matrix-based proteins, such as fibronectin or laminin, enables amplification of the surface properties initially defined by the functionalized coatings. Moreover, patterned adsorption of proteins can be used in conjunction with patterned areas of protein-resistance to induce patterned or spatially-controlled cell adhesion. Control of cell adhesion in this manner is expected to be essential in the development of micro-scaled cell-based diagnostics, especially those using microfluidics, as well as in promoting biocompatibility of implantable materials. Preliminary results from this work will highlight these advantages of functionalized CVD coating of poly[4-benzoyl-p-xylylene-co-p-xylylene] in the context of controlled protein adsorption and cell adhesion.