(640c) Multipotent Polymer Coatings Based on Chemical Vapor Deposition Copolymerization
The controlled and stable immobilization of multiple types of biomolecules to a surface is a critical challenge in several emerging research fields, such as the regulation of cell shapes, the development of advanced biological assays, or scaffolds for regenerative medicine. While a range of methods has been developed for the immobilization of a single type of biomolecule to artificial substrates, very few concepts are available for the precious immobilization of multiple biomolecules in a controllable fashion. Using chemical vapor deposition (CVD) copolymerization, we have developed a simple strategy towards multi-functional surfaces presenting two different biological ligands in controllable ratios.
Towards this goal, CVD technology was used to copolymerize two reactive monomers, 4-aminomethyl-[2.2]paracyclophane and 4-trifluoroacetyl-[2.2]paracyclophane in different ratios, without cross-reaction, to produce the corresponding copolymers as thin film coatings. FTIR spectroscopy verifies the presence of both aminomethyl and ketone functional groups in their corresponding proportions. High-resolution C1s XPS on the surface also confirms the theoretical bulk composition [C1s: 83.26% (calc. 84.76%), N1s: 2.84% (calc. 3.05%), F1s: 8.54% (calc. 9.15%), O1s: 5.35% (calc. 3.05%);]. Although the trifluoroacetyl homopolymer is semicrystalline after annealing at 120 oC, X-ray diffraction of the copolymer films shows no crystallinity after annealing, indicating homogenous mixing of monomers. As a way of demonstrating the copolymer's parallel reactivity, an amine-reactive ligand (Atto 655 NHS ester) and a keto-reactive ligand (biotin hydrazide + rhodamine-linked streptavidin) were reacted on the copolymer surface in proportion to the monomer ratios, as verified by fluorescence scanning. These results have broader applications in biomaterials engineering, microfluidics, and diagnostic testing. For example, one could fine-tune two different surface properties independently, a powerful tool for optimizing many biological interfaces. Also, this technology could be used as part of a multivariable sensor or bioassay. An added advantage is that surface geometry is not a limiting factor for CVD, and devices with complex geometries can be coated.
Y. Elkasabi, H.Y. Chen, J. Lahann. Adv. Mater. 2006 In press