Polydopamine coated substrates as scaffolds for glycopolymer brushes attached via one-pot 'grafting from' synthesis and para-fluoro 'click chemistry' for biomedical applications

摘要

The biomimetically inspired polydopamine coating is a facile surface coating process suitable for a range of substrates. These coatings are robust and provide a wide array of accessible functional groups for further surface modification. This dissertation describes the use of polydopamine coatings on magnetoelastic alloy substrates and silicon dioxide nanoparticles. The magnetoelastic alloys can function as biochemical detection devices if suitably coated with a ‘chemically responsive layer’ to provide an attractive surface for analytes. The silicon dioxide nanoparticles can be further processed to create specially coated hollow particles for ‘smart’ delivery of therapeutic agents. The successful creation of the polydopamine coatings was confirmed with ATR-FTIR, contact angle measurements and thermogravimetric analysis for the particles.Once the polydopamine coatings were created they were further modified to create glycopolymer coated surfaces for protein binding. These glycopolymer coatings were created by attaching polymer brushes to the polydopamine coated substrates. Both traditional ‘grafting to’ and ‘grafting from’ techniques were employed to create polymer brushes of varying grafting densities. Reversible addition-fragmentation chain transfer (RAFT) controlled radical polymerization techniques were used to grow polymer brushes with narrow dispersities and specific molecular weights. While ‘grafting from’ techniques produce a higher grafting density, they typically involve two steps – initiator deposition followed by polymerization. A one-pot single-step method of simultaneously growing a polymer brush and attaching it to a surface was successfully created utilizing a carbonyl azide-terminated RAFT agent for isocyanate coupling. The polymer brush coatings offer the advantages of increased effective surface areas over bulk polymer coatings per unit substrate surface area. Poly(pentafluorostyrene) polymer brushes were created and then simple ‘thiol-click’ reactions with 1-thio-beta-glucose were performed to convert the poly(pentafluorostyrene) polymer brushes to glycopolymers. Thermogravimetric analysis, ATR-FTIR and contact angle measurements confirmed the successful glucosylation of the polymer brushes. Preliminary protein binding results confirmed via confocal microscopy and fluorescence lifetime imaging microscopy (FLIM) showed that protein binding successfully occurred on the glycopolymer coated materials. This work represents the unique combination of polydopamine coatings with glycopolymer brushes via facile synthesis routes to create materials with potential in biochemical detection and as ‘smart’ drug delivery devices.