The use of metal-island-coated pH-sensitive swelling polymers for biosensor applications

Abstract

A new optical sensor principle for the case where the sensor/analyte reaction results in the change of non-spectroscopic parameters is presented. Changing the analyte concentration results in the pH-dependent swelling of special polymers. The sensor material is part of an optical thin-film system, which transforms the variations in volume of the polymer into spectral information. A crosslinked polyvinylpyrrolidone photopolymer has been developed to obtain a gel matrix showing ion/pH-dependent swelling and good attachment to the sensor surface as well as photostructuring properties. For the construction of a biosensor, the device is covered by a photostructured polyvinylpyrrolidone membrane incorporating the desired enzymes. Urea is quantified by using immobilised urease that converts the analyte into carbon dioxide and ammonia.