Highly selective and sensitive glucose sensors based on organic electrochemical transistors using TiO2 nanotube arrays-based gate electrodes

• TNTAs are used as the gate electrode of the OECT-based glucose sensor.
• The device shows a linear response from 100 nM to 5 mM.
• Glucose can be selectively detected in the presence of interferences.
• The device also presents a good stability and reproducibility.

In organic electrochemical transistor (OECT) based glucose sensors Pt-based electrodes are usually used as the gate electrodes due to its excellent electrocatalytic activity. In this paper, a cheap and biocompatible material, TiO2 nanotube arrays (TNTAs), was used as the gate electrode of the OECT device for the first time. It is encouraging that the sensing performance of OECTs using TNTAs-based gate electrodes is comparable to or better than those of the previously reported OECTs using Pt-based gate electrodes. Highly sensitive and selective OECT devices can be obtained by modifying TNTAs electrodes with Pt nanoparticles (Pt-NPs) and enzyme (glucose oxidase). The device shows a linear response to the logarithm of glucose concentration over the range from 100 nM to 5 mM, and the detection limit as low as 100 nM was achieved, which is three orders of magnitude lower than that of a conventional electrochemical measurement with the same electrode. On the other hand, the glucose can be selectively detected in the presence of interferences, such as ascorbic acid and uric acid, when the gate electrode is modified with Nafion. Moreover, the device presents a good stability and reproducibility. By modifying with other specific enzymes and nanomaterials, it is expected that many other type of enzyme sensors with high sensitivity and selectivity could be realized.

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