Enzyme-Free Electrochemical Sensors for in situ Quantification of Reducing Sugars Based on Carboxylated Graphene–Carboxylated Multiwalled Carbon Nanotubes–Gold Nanoparticle–Modified Electrode

Abstract

The reducing sugars of plants, including glucose, fructose, arabinose, galactose, xylose, and mannose, are not only the energy source of plants, but also have the messenger function of hormones in signal transduction. Moreover, they also determine the quality and flavor of agricultural products. Therefore, the in situ quantification of reducing sugars in plants or agriculture products is very important in precision agriculture. However, the upper detection limit of the currently developed sugar sensor is not high enough for in situ detection. In this study, an enzyme-free electrochemical sensor for in situ detection of reducing sugars was developed. Three-dimensional composite materials based on carboxylated graphene–carboxylated multi-walled carbon nanotubes attaching with gold nanoparticles (COOH-GR–COOH-MWNT–AuNPs) were formed and applied for the non-enzymatic determination of glucose, fructose, arabinose, mannose, xylose, and galactose. It was demonstrated that the COOH-GR–COOH-MWNT–AuNP-modified electrode exhibited a good catalysis behavior to these reducing sugars due to the synergistic effect of the COOH-GR, COOH-MWNT, and AuNPs. The detection range of the sensor for glucose, fructose, arabinose, mannose, xylose, and galactose is 5–80, 2–20, 2–50, 5–60, 2–40, and 5–40 mM, respectively. To our knowledge, the upper detection limit of our enzyme-free sugar sensor is the highest compared to previous studies, which is more suitable for in situ detection of sugars in agricultural products and plants. In addition, this sensor is simple and portable, with good reproducibility and accuracy; it will have broad practical application value in precision agriculture.

Advances in two‐dimensional engineered nanomaterials applications for the agro‑ and food‐industries

“…Focusing on the agro‐industrial area, there are plenty of reports where nanomaterials are investigated for sensing applications 54‐56 . Recent studies show, for instance, the use of carboxylated CNTs and graphene for an increased detection range of reducing sugars in plants, as a part of a technological trend dubbed ‘precision agriculture’ 57 . Another recent article reports on the use of interdigitated electrodes made of multiwalled CNTs for phosphate concentration determination in water samples intended for agricultural use 58 .…”

“…[54][55][56] Recent studies show, for instance, the use of carboxylated CNTs and graphene for an increased detection range of reducing sugars in plants, as a part of a technological trend dubbed 'precision agriculture'. 57 Another recent article reports on the use of interdigitated electrodes made of multiwalled CNTs for phosphate concentration determination in water samples intended for agricultural use. 58 This work proposes machine learning techniques within a whole Internet of Things system for phosphate detection, based in the nanosensor device, demonstrating the practical applicability of these kind of nanoelectronic systems.…”