Sol–gel based thermal biosensor for glucose Original Research Article

A sol–gel (SG) based glucose biosensor using thermometric measurement is reported. The enzymes (glucose oxidase, GOD and catalase, CAT) were entrapped on the surface of reticulated vitreous carbon cylinder (RVC cartridge) using SG as a binder. This ‘RVC cartridge’ was placed within the column of an enzyme thermistor (ET) device. Injection of various d-glucose concentrations resulted in changing the heat content of the circulating buffer, recorded as a thermometric peak by a sensitive thermistor. Independent calibration curves between 10 and 50 mM and between 0.2 and 1 mM d-glucose was obtained by plotting the d-glucose concentration versus the thermometric peak height. The sensitivity of the response was optimized to 1 ml min−1 flow rate of the buffer. The stability of the entrapped GOD/CAT stored at room temperature (25°C) or 4–10°C was 3 or 6 months, respectively. The effect of dissolved oxygen and other interferents such as acetaminophen, ascorbic acid, aspartic acid, glutamic acid, urea and uric acid, on the catalytic activity of the enzyme was also investigated. This system was employed to detect glucose in samples of fruit juice, coca cola and human blood serum.