IMPROVEMENT OF ENZYMATIC-ACTIVITY AND LIFETIME OF LANGMUIR-BLODGETT-FILMS BY USING SUBMICRON SIO2 PARTICLES

Improvements in the sensitivity and the lifetime of biosensors continue to be a goal of investigation. In this paper, it is reported that the activity and lifetime of a glucose oxidase (GOD) membrane has been improved by the introduction of submicron hydrophobic SiO2 particles with a diameter of about 30 nm. A new method for the preparation and purification of submicron hydrophobic particles has been developed for this purpose. The enzymatic activity of immobilized GOD has been assessed by two methods: by measuring the fading of indigo camine dye oxidized by H2O2 released from the enzymatic reaction, and by an electrochemical method. Experimental results showed that the ultrafine hydrophobic SiO2 particles combined with Langmuir-Blodgett (LB) films can help the incorporation of GOD into the films. After incorporation, GOD retains its enzymatic activity. In addition, GOD activity per area of membrane increased because of the stable adsorption of GOD on the SiO2 particle surface. The lifetime of the GOD-LB film containing SiO2 particles is much longer than the lifetime of GOD-LB film without SiO2 particles.