Activity and stability of glucose biosensor based on Escherichia coli immobilized on zeolite-glutaraldehyde

Abstract

Glucose biosensor based on Escherichia coli have been developed recently. Despite of some drawbacks, such as the activity of glucose dehydrogenase (GDH) and the lower electrode stability. The use of zeolite in biosensors can increase the enzyme activity, while the use of glutaraldehyde (GA) as a cross-link can improve the electrode stability. The design optimization employed response surface methods (RSM). The optimum conditions activity of GDH cells with E. coli immobilized was at temperature 30 °C, pH 6, glucose 15 mM, pyrroloquinoline quinone (PQQ) 3.5 μM, zeolite 150 mg/mL, and GA 14.05%. This biosensor was able to detect up to 50 mM glucose concentration. The reaction kinetics followed Lineweaver-Burk equation. KM app value and Imaks app GDH cells E. coli immobilized in a row is 2.69 mM and 3.73 μA. The biosensor was relatively stable at 70–80% for 4 days. Therefore, the use of zeolite-GA as an immobilization matrix can enhance the activity of the stable bacterial cell of GDH-E. coli.

Biosensor glukosa berbasis Escherichia coli hingga saat ini telah dikembangkan. Pengembangan ini memiliki beberapa kelemahan, yaitu aktivitas glukosa dehidrogenase (GDH) dan stabilitas elektrode rendah. Penggunaan zeolit pada biosensor dapat meningkatkan aktivitas enzim, sedangkan penggunaan glutaraldehida (GA) sebagai bahan taut-silang dapat meningkatkan stabilitas elektrode. Perancangan percobaan optimisasi dilakukan menggunakan metode permekaan respons (RSM). Kondisi optimum aktivitas biosensor ini ialah suhu 30 oC, pH 6, konsentrasi glukosa 15 mM, konsentrasi pirolokuinolina kuinon (PQQ) 3.5 μM, zeolit 150 mg/mL, dan konsentrasi GA 14.05%. GDH sel E. coli terimobilisasi dapat mendeteksi konsentrasi glukosa hingga 50 mM. Reaksi kinetika GDH sel E. coli terimobilisasi mengikuti persamaan Lineweaver-Burk. Nilai KM app dan Imaks app biosensor ini secara berturut-turut adalah 2.69 mM dan 3.73 μA. Aktivitas GDH sel bakteri relatif stabil sebesar 70–80% selama 4 hari. Oleh karena itu, penggunaan zeolit-GA sebagai matriks imobilisasi dapat meningkatkan aktivitas GDH sel bakteri E. coli yang relatif stabil.