Studies of polymeric membranes modified for amperometric H2O2 and pO2 sensing with needle-type electrodes

Abstract

Materials used for medical devices are far from ideal for the body, so polymers are applied at the outermost region to counteract the body's natural defences. Component-based failures such as delamination and biocompatibility-based failures such as membrane fouling and degradation still remain a signi cant challenge. This study focuses on the surface properties and modi cation of polyurethane and silicone rubber as coating material for amperometric sensing devices. E ective synthesis of polyurethane, as well as surface modi cation techniques performed on polymers already attached to sensing devices, are proposed. Phase inversion resulted in increased soft segment content on the surface (con rmed by FTIR with a decreased C=O/C=C ratio). It is proposed that such an optimised polymer surface enhances the yield of further surface modi cation, such as hydroxylation (using potassium peroxodisulphate) and sulphonation (employing sodium hydride, triisobutylaluminium and 1,3 propane sultone). A novel method to generate an SO3-derivatised PU surface was proposed. Additionally, successful synthesis of silicone rubber for induced permeability of H2O2 was demonstrated. The physical and chemical properties of these modi ed polymers were examined and evaluated via FTIR, SEM, TGA and contact angle measurements. The biocompatibility of modi ed polymers was con rmed with retarded protein adsorption; cytotoxicity testing showed that polymers were non-toxic to cells. Steady state amperometry on polymer modi ed needle-type electrodes showed enhanced performance with surface modi ed polymers to oxygen and H2O2, both of which are potential biological assay targets. Synthesised Prussian Blue (redox mediator) on platinum surfaces showed that the electrochemical response to H2O2 was increased threefold; and in combination with sulphonated polyurethane, interfering current responses could be successfully eliminated.