Development of an electrochemical sensor using carbon nanotubes and hydrophobic natural deep eutectic solvents for the detection of α-glucosidase activity in extracts of autochthonous medicinal plants

Abstract

The present work describes for the first time the use of a hydrophobic natural deep eutectic solvent (H-NADES) as a dispersant for carboxylated nanotubes for the design and construction of an electrochemical sensor for the assay of α-glucosidase and its inhibitors. In this work, we used as the electrochemical probe the product of the enzymatic reaction, which consists of two redox groups and generates the analytical signal. The combination of de carboxylic multi-walled carbon nanotubes (MWCNTc) and the H-NADES of thymol and lactic acid (TLa) increases the electroactive surface area and promotes electron transfer of the electrode modified with carbon nanotubes. The electrochemical sensor enabled the detection of α-glucosidase in a range of 0.004-0.1 U mL^-1 with a detection limit of 0.0013 U mL^-1, which is lower than most existing methods. In addition, two α-glucosidase inhibitors, acarbose and quercetin, and two plant extracts, Schinus molle and Eugenia uniflora, were evaluated to assess the feasibility of screening potential antidiabetic drugs, and the IC50 values were 5.37 μg mL^-1 and 5.28 μg mL^-1. Thus, this sensing strategy represents the beginning of the incorporation of NADES in the development and design of novel sensors and their application in electrochemistry and medical analysis.

Keywords: Carbon nanotubes; Electrochemical sensors; H-NADES; Medicinal plants; Response surface methodology; α-glucosidase.