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

Area of Science:

• Materials Science
• Chemical Engineering
• Nanotechnology

Background:

• Graphene exhibits high carrier mobility and surface sensitivity, making it suitable for sensor applications.
• Chemical reactions involving bond changes are crucial but challenging to detect sensitively.
• The thiol-ene reaction, a specific type of click chemistry, offers a model for studying bond transformations.

Purpose of the Study:

• To develop a highly sensitive electrical detection method for chemical reactions involving bond changes.
• To utilize graphene field-effect transistors (FETs) for real-time monitoring of the thiol-ene reaction.
• To demonstrate the selective detection of methanethiol (MeSH) using a graphene-based sensor.

Main Methods:

• Graphene field-effect transistors (FETs) were fabricated and functionalized with N-(9-Acridinyl)maleimide (NAM) via π-interaction.
• The thiol-ene reaction was initiated by exposing the functionalized graphene FET to methanethiol (MeSH) under ultraviolet irradiation.
• Changes in the transfer characteristics of the graphene FET were measured to quantify the reaction.
• Control experiments were performed using acetic acid, ethanol, and methanol to assess selectivity.

Main Results:

• The functionalization of graphene with NAM was confirmed using attenuated total reflection Fourier transform infrared spectroscopy and cyclic voltammetry.
• Exposure to 10 parts per billion (ppb) of MeSH induced a significant negative shift of 2 V in the graphene FET's transfer characteristics, indicating a successful thiol-ene reaction.
• Non-target molecules like acetic acid, ethanol, and methanol showed minimal or opposite shifts, confirming the reaction's specificity.
• The method successfully detected ultralow concentrations of MeSH (down to 10 ppb or 0.2 ng).

Conclusions:

• A novel graphene FET-based sensor enables sensitive and selective electrical detection of the thiol-ene chemical reaction.
• The proposed method can detect bond-change reactions at extremely low analyte concentrations.
• This approach holds promise for developing advanced chemical sensors for various applications.