Abstract
A three-electrode amperometric biosensor for the detection of two different saccharides (lactose and glucose) in aqueous solutions is described. On the graphite working electrode, the glucose oxidase (GOD) andβ-galactosidase (β-gal) were coimmobilized by means of covalent bonding. The response of the biosensor as a function of the relative concentration of the two immobilized enzymes was investigated and the best working conditions were identified by measuring the sensitivity and the linear range response. In particular, our best lactose biosensor shows a linear range up to 0.010 mM and a limit of detection (LOD) and a sensitivity equal to 0.001 mM and 850 ± 81 μA/mM, respectively. For glucose, the values of the above-mentioned parameters are equal to 0.015 mM for the linear range, 0.001 mM for LOD, and 505 ± 55 μA/mM for the sensitivity. The working parameters of our biosensors are significant in comparison with other biosensors developed for concentration determination of the two saccharides investigated in the present work. In particular, low (LOD) and high sensitivities are obtained for lactose and glucose. To challenge our biosensor with real samples, it was tested using fruit juices, skim milk, and whey.
Highlights
Saccharides play a relevant role in the food industry and the research for the development of reliable and low-cost biosensors is always very active [1]
The sensitivities range between 380 and 850 μA/mM. These results show that the highest sensitivity is still obtained for the electrode prepared with 2 mg/ml of glucose oxidase (GOD) and 6 mg/ml of β-gal
The concentrations of saccharides measured with our biosensor are in good agreement with those obtained using commercial kits. These results demonstrate that the proposed biosensor may be used in measuring glucose or lactose contents in real food samples
Summary
Saccharides play a relevant role in the food industry and the research for the development of reliable and low-cost biosensors is always very active [1]. In the last years, the determination of this parameter in foods has acquired a significant role since many individuals manifest lactose intolerance and cannot consume milk and dairy products without suffering and gastrointestinal disorders [5]. This intolerance is related to lack of the required enzyme lactase (β-galactosidase) in the digestive system that inhibits the metabolization of lactose into galactose and glucose [6]. The working parameters of the prepared devices have been compared with the performances of other similar biosensors reported in the literature This comparison has confirmed the effectiveness of multienzymes biosensors for lactose and glucose concentration determination. The proposed biosensor has been tested with real samples using fruit juices, skim milk, and whey
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