Effect of Electrode Modification with Chitosan and Nafion® on the Efficiency of Real-Time Enzyme Glucose Biosensors Based on ZnO Tetrapods

Abstract

Noninvasive, continuous glucose detection can provide some insights into daily fluctuations in blood glucose levels, which can help us balance diet, exercise, and medication. Since current commercially available glucose sensors can barely provide real-time glucose monitoring and usually imply different invasive sampling, there is an extraordinary need to develop new harmless methods for detecting glucose in non-invasive body fluids. Therefore, it is crucial to design (bio)sensors that can detect very low levels of glucose (down to tens of µM) normally found in sweat or tears. Apart from the selection of materials with high catalytic activity for glucose oxidation, it is also important to pay considerable attention to the electrode functionalization process, as it significantly contributes to the overall detection efficiency. In this study, the (ZnO tetrapods) ZnO TPs-based electrodes were functionalized with Nafion and chitosan polymers to compare their glucose detection efficiency. Cyclic voltammetry (CV) measurements have shown that chitosan-modified ZnO TPs require a lower applied potential for glucose oxidation, which may be due to the larger size of chitosan micelles (compared to Nafion micelles), and thus easier penetration of glucose through the chitosan membrane. However, despite this, both ZnO TPs modified with chitosan and Nafion membranes, provided quite similar glucose detection parameters (sensitivities, 7.5 µA mM−1 cm−1 and 19.2 µA mM−1 cm−1, and limits of detection, 24.4 µM and 22.2 µM, respectively). Our results show that both electrodes have a high potential for accurate real-time sweat/tears glucose detection.

Electrochemical Immunosensor for the Determination of Antibodies against Prostate-Specific Antigen Based on ZnO Nanostructures

“…The optimal parameters for ZnO and PSA immobilization were chosen based on previous research [ 60 ]. The 2% Nafion mixture was prepared by diluting 10% Nafion solution in ethanol and adding NaOH to increase the pH until it reached a value of 7.0.…”

Unprecedented Multifunctionality in Novel Monophase Micro/Nanostructured Ti‐Zn Alloy

“…This anti-interference polymer plays no significant role in the effectiveness of glucose detection. [49,50] Especially for sucrose and uric acid, noise has aroused during spike followed by drain current reducing back to baseline current. This could probably be due to a disturbance in the formed electric double layer while adding analytes.…”

Fabrication and Optimization of Nafion as a Protective Membrane for TiN-Based pH Sensors

“…Significant interest in the special features of Nafion has been shown in numerous research fields and applications, such as fuel cells and batteries [ 19 ], chemical sensors [ 20 ], biosensors [ 21 , 22 , 23 ], and medical diagnosis technologies [ 24 , 25 ]. Nafion has received a lot of attention recently in the context of electrochemical sensors for biomedical and environmental applications as a membrane or electrode modification [ 26 , 27 , 28 ]. The chemical structure of Nafion allows it to behave as a semipermeable membrane, where only protons can reach the electrode and all other types of ions are blocked.…”