The development of calorimetric biosensors using chip thermistors

Abstract

Conventional enzyme thermistors need a precise thermostat in order to cancel temperature variations in the surrounding environment. However, such precise thermostats are large and expensive, so applications of enzyme thermistors are limited. We have used chip thermistors as temperature transducers in order to develop an inexpensive and portable enzyme thermistor system. The chip thermistor has a small heat capacity, so it can detect small enthalpy changes of enzymatic reactions with high sensitivity. The enzyme and bovine serum albumin (BSA) were immobilized directly on the surface of two chip thermistors respectively. The temperature difference between the enzyme immobilized thermistor and the BSA immobilized reference thermistor was measured in an insulated cell, allowing detection of small temperature changes. Using glucose oxidase (GOD) as an enzyme, a linear calibration curve was obtained for glucose concentrations in the range from 1 mM to 5 mM. This linear concentration range must be enhanced before the system can be applied to practical use.