Abstract
In this paper, a simple and specific graphene quantum dots (GQDs)-based fluorescent biosensor adopted for the determination of glucose based on the combination of the enzyme-coupled method and fluorescence quenching mechanism is demonstrated. Glucose was oxidized by the enzyme glucose oxidase (GOx), forming hydrogen peroxide (HO) via the catalysis by horseradish peroxidase (HRP). HO was then employed to oxidize phenol to quinone, which led to effective quenching effect in the GQDs–GOx–HRP–phenol system. By optimizing the reaction conditions of the GQDs-enzyme system, a linear relationship between the concentration of glucose and the fluorescence intensity over a range of 0.2–10 mol/L was obtained. The limit of detection for glucose is 0.08 mol/L. The present biosensor for the determination of glucose showed satisfactory reproducibility and accuracy in human serum samples. Since the enzymes have high specificity and unique affinity to the certain substance, the enzyme-coupled system promises a sensitive way for further detection of those chemicals which could be oxidized by enzymes and generated HO or glucose. GQDs and other fluorescent materials coupled with several enzymes can be applied to extensive sensing field.
Highlights
Glucose is a basic and widely-used monosaccharide that can be found in both human bodies and other species
The principle of Graphene quantum dots (GQDs)-glucose detection is based on the combination of glucose enzyme reaction and the quenching effect of quinone produced on the GQDs, and the idea of the sensing system is illustrated in Scheme 1
A simple and sensitive approach for glucose determination based upon the combination between specific enzymatic reaction and quenching effect of GQDs is reported
Summary
Glucose is a basic and widely-used monosaccharide that can be found in both human bodies and other species. Glucose acts as the raw material and the intermediate product of respiration and metabolism, and an unbalanced glucose level in the human body can lead to such disease as diabetes which is considered a principal health problem that negatively affects millions of people in the world [1,2]. Glucose monitoring and diabetes diagnostic have been continuous concerns among the public. The fast and accurate monitoring of glucose level, mainly in blood, is necessary for diagnostic and treatment [3,4]. Because of the convenient implementation and high sensitivity, several types of bio-probes have been made using enzymes and some fluorescent material for fast and deep sensing detection [13,14]
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