Controlled and tailored modification of polymer interfaces for use in biosensing systems
For biosensing applications it is often desirable to immobilise biomolecules securely on the electrode surface. The research described here was performed to develop and characterise modified conducting polymers suitable for use in the development of biosensor arrays. The research pursued centred around a post polymer-deposition modification strategy based on nucleophilic substitution of the pentafluorophenol group of the polymerised pyrrole derivative, pentafluorophenyl 3-(pyrrol-1-yl) propanoate (PFP). The activated ester present within this derivative is as an ideal reaction site for amine terminated species. Initially, electrochemical polymerisation growth conditions were determined and controlled to produce homopolymer and copolymer films with different structural and electrochemical characteristics. These polymer films were subsequently modified through various chemical reactions (e.g. with biotinylated species) to produce templates that could be used to biosensor developments. Furthermore, an important aspect in the development of a biosensing interface is the minimisation of non-specific adsorption and to that end a strategy was developed that involved modifying poly(PFP) films with poly(propyleneglycol) motifs. Usefully, an XPS based technique was developed to determine the extent of adsorption of labelled biological macromolecules on the modified poly(PFP) surfaces. Significantly, towards the development of a multianalyte biosensing substrate, a method was developed to control the reaction of solution based amine terminated species with the homopolymer poly(PFP). This involved electrochemically doping the polymer film to inhibit/promote nucleophilic reaction with amine containing species. Preliminary examples are given of the application of this technique was to micropattern species on multi-digitated electrodes.