Electrical Detection of Molecular Transformations Associated with Chemical Reactions Using Graphene Devices

Abstract

This study proposes a method to electrically detect chemical reactions that involve bond changes through reactions on graphene surfaces. To achieve a highly sensitive detection, we focused on the thiol–ene reaction that combines the maleimide and thiol groups. Graphene field-effect transistors (FETs) were used to detect the binding changes of the modified molecules. Graphene has high carrier mobility and is sensitive to changes in the electronic state of its surface. Graphene has been used as a sensor to detect low-concentration targets with high sensitivity. N-(9-Acridinyl)­maleimide (NAM) was chosen as the modified molecule to immobilize maleimide on graphene through π-interaction, and methanethiol (MeSH) was set as the target thiol. The modification of NAM to graphene was first confirmed by attenuated total reflection Fourier transform infrared spectroscopy, and the modification density was 0.5 ± 0.1/nm2 through cyclic voltammetry. Owing to a bond exchange, the transfer characteristics of the graphene FET shifted by 2 V to the negative direction after being exposed to MeSH at 10 parts per billion (ppb), equivalent to 0.2 ng, under ultraviolet irradiation. With 5000 ppb of acetic acid, it only shifted 0.7 V. With 1000 ppb of ethanol and 10,000 ppb of methanol, it shifted to the positive direction by 0.4 and 0.6 V, respectively. Because the nontarget molecule showed only a slight response, a thiol–ene chemical reaction was detected. The proposed method can detect the bond-change reaction using an ultralow concentration of MeSH, which indicates that at least 10 ppb (or 0.2 ng) of MeSH was detected by the graphene FET.

Organic Molecular Detection without Debye-Length Limitation by Desorption of Receptor from the Surface of a Graphene Field-Effect Transistor

“…Additionally, straight lines with a slope of 2.2 for the case affected by strain and 0.7 for the one affected by hole doping are shown in Figure c. − The compressive strain of the samples decreased after modification, indicating the enhancement of the flatness of the underlying graphene by the π-conjugated system of pyrene . Hole doping also increased after modification, which is consistent with the observation that graphene is hole-doped when modified with pyrene. , These results confirm the modification of PMI on graphene.…”

“…40 Hole doping also increased after modification, which is consistent with the observation that graphene is hole-doped when modified with pyrene. 41,42 These results confirm the modification of PMI on graphene.…”

Two-Dimensional Field-Effect Transistor Sensors: The Road toward Commercialization

“…Copyright 2020 The Royal Society of Chemistry. (b) Adapted from ref . Copyright 2021 American Chemical Society.…”

“…Despite the significant progress made for single analyte sensing, multiplex sensing remains challenging due to the imperfect device selectivity for VOCs. Efforts have been made in multianalyte sensing with a wide range of VOCs assisted by light irradiation. , As an example, Sakamoto and colleagues proposed an irradiation-assisted strategy to detect methanethiol via N -(9-acridinyl)­maleimide-modified GFET sensors . The response upon 10 ppb methanethiol was up to 4 times greater than that of 10 000 ppb methanol (Figure b), indicating its evident selectivity for different VOCs.…”

“…422,423 As an example, Sakamoto and colleagues proposed an irradiation-assisted strategy to detect methanethiol via N-(9-acridinyl)maleimide-modified GFET sensors. 422 The response upon 10 ppb methanethiol was up to 4 times greater than that of 10 000 ppb methanol (Figure 19b), indicating its evident selectivity for different VOCs. Also, a similar light-assisted method was employed to enhance the device selectivity during the detection of acetone and ethanol (Figure 19c).…”