An amperometric sensor employing glucose oxidase immobilized on nylon membranes with different pore diameter and grafted with different monomers

Glucose oxidase (GOD) was immobilized on nylon membranes having three different pore diameters and chemically grafted with glycidyl methacrylate (GMA) or butyl methacrylate (BMA). Hexamethylenediamine (HMDA) and glutaraldehyde (GA) were used as spacer and coupling agent, respectively. ochemical and electrochemical behaviour of the membranes has been studied as a function of pH, temperature and glucose concentration with reference to the grafted monomer and the membrane pore diameter. The behaviour of the soluble GOD has also been studied in order to see the modification induced by the immobilization process on the enzyme activity. found that the values of the biosensor sensitivity, maximum saturation current and electrochemical affinity increase with the membrane pore diameter, indipendently of the nature of the graft monomer. Opposite behaviour was found relatively to the extension of the linear response ranges and the average response times. eference to the parameters increasing with the pore diameter it was found that membranes grafted with GMA had higher values than those of the membranes grafted with BMA. The contrary occurred to the values of the parameters decreasing with the increase of the pore diameter. mical and electrochemical results have been discussed in terms of the different limitations to the diffusion of substrate and reaction products across the catalytic membrane introduced by the different pore diameters and by the different hydrophobicity of the graft monomers.