Biosensors for determination of galactose with galactose oxidase immobilized on eggshell membrane

A galactose biosensor was first fabricated using a galactose oxidase-immobilized eggshell membrane and an oxygen electrode. The detection scheme was based on the depletion of dissolved oxygen content upon exposure to galactose solution, and the decrease in oxygen level was monitored and related to the galactose concentration. The effects of pH, buffer compositions, phosphate buffer concentration, and temperature on the biosensor were investigated. The linear range is 0.1 to 8.5 mM with relative standard deviation (RSD) is 3.74% and the response time is 100 s. Some possible interferents such as L-ascorbic acid, ethanol, sucrose, glucose, maltose, and fructose did not give significant interference and retained 83.6% of initial enzyme activity after 3 months when stored in a pH 7.0 phosphate buffer solution at 4 degrees C. The proposed biosensor was applied to the determination of galactose added to plasma samples with the recoveries of galactose is 94%-110%.