Modified gas-permeable silicone rubber membranes for covalent immobilisation of enzymes and their use in biosensor development

Novel enzyme membranes are introduced. Modified polymeric gas-permeable lay ers were developed enabling biological components which have available reac tive groups (-NH2, -OH, -SH, -COOH) to couple covalently on to their surfac es. Therefore, gas-permeable two component room temperature vulcanising (2K -RTV) silicone rubber was modified using additional cross-linking agents. T riethoxysilanes with functional groups on their side chains such as epoxy o r amino groups were used. A special attribute of the resulting gas-permeabl e membranes is that their formation and modification occur simultaneously d uring one reaction step. IR spectroscopy was used to observe the changes in the polymeric structure due to the reaction with the additional cross-link ing agents. Sensors equipped with these layers are suitable to measure diss olved gases such as O-2, CO2 and NH3 consumed or produced by enzymes conver ting their substrates. Determination of glucose, a well investigated enzyma tic detection process, was chosen to demonstrate the applicability of the e nzyme immobilisation. Glucose oxidase was immobilised on the membranes and glucose was detected by amperometric measurement of oxygen consumption. It is expected that this immobilisation method will also be useful for miniatu rised planar biosensors.