Glucose biosensor based on ENFET doped with SiO2 nanoparticles

While remarkable progress has been made in developing enzyme field-effect transistors (ENFETs), the immobilization of enzymes remains a significant challenge. Recently, nanometer materials such as gold, silver and metal oxide nanoparticles have been widely used in biosensors because of their big surface area and good biocompatibility. However, there are few reports about fabricating biocatalytic layer on ENFETs with nanoparticles. Here, SiO2 nanoparticles were introduced into the construction of ENFET. A glucose-sensitive ENFET was fabricated based on the modification of the gate surface of ion-sensitive field-effect transistors (ISFETs) with SiO2 nanoparticles and glucose oxidase (GOD). Compared with the one without SiO2 nanoparticles, the proposed sensor shows obviously enhanced sensitivity and extended lifetime. It infers that SiO2 nanoparticles can provide a biocompatible environment and improve the enzyme activity, and prevent the immobilized enzymes from leakage as well. The linear range of the ENFET is 0.05-1.8 mM, and the detection limit is ca. 0.025 mM. The effects of buffer concentration, pH and ionic strength were also examined. The biosensor has good stability and reproducibility, and it can be used for the determination of glucose. (C) 2003 Elsevier B.V. All rights reserved.