Development Of Glucose Enzyme Sensors Based On Glucose Oxidase Immobilized On Two Plant Materials

There are considerable high efficiency and specialization for the enzyme catalysis. But, to our regret, free enzyme is usually not stable and cannot be easily reused. A technology of enzyme immobilization makes the study of increasing enzymatic stability and reusing enzyme feasible. It emphasizes the process that a soluble enzyme combines with an insoluble support to form an insoluble immobilized enzyme. To date immobilization methods and immobilization materials have been largely enriched and developed. Nevertheless, there is still a need to search for cheaper, more convenient and effective methods and supports for enzyme immobilization.Plant materials of tomato peel and bamboo shell inner membrane, a regular array of microporous structure and a clear stripe image, respectively, can provide microenvironment for the immobilized enzyme so that the activity of the immobilized enzyme is retained. Glucose oxidase (GOx) was immobilized on the tomato peel and bamboo shell inner membrane with glutaraldehyde as a cross-linking agent. This immobilized method is simple and convenient. Moreover,the enzyme was tightly linked biomaterials with a considerable stability.The tomato peel immobilized GOx was applied on a Clark-type oxygen electrode to form an enzyme electrode. The detection mechanism of the sensor is based on the enzymatic oxidation of glucose by oxygen as displayed in Eq. D-glucose + O2 + H2 O glucoseoxidase > D-gluconic acid + H2 O2 and the depletion of dissolved oxygen content upon exposure to glucose solution. The decrease in the oxygen level was monitored and related to the glucose concentration. The sensor showed fast response (6s), excellent reproducibility (RSD=1.8%, n=10), selectivity and more measurement times (after 3000 times determinations, the enzyme activity was retained 85% of initial activity).During the above enzymatic reaction of glucose, dissolved oxygen can be fluorometrically detected since oxygen molecules efficiently quench the fluorescence of [Ru(dpp)3][(4-Clph)4B]2. Bamboo inner shell membrane immobilized GOx was applied on F-4500 spectrofluorometer to form a fluorescent glucose enzyme sensor. The detection scheme of the sensor is based on the depletion of dissolved oxygen content upon exposure to glucose solution and the increase in the fluorescence intensity of the [Ru(dpp)3][(4-Clph)4B]2 and related to the glucose concentration. Due to the excellent reproducibility (RSD=:3.0%, n-10), selectivity and stability (the glucose biosensor retained 95% of its initial response rate after 8-month storage periods at 4°C), the glucose biosensor was successfully applied to determine glucose content in wines and glucose injection samples.