Peptide-modified electrolyte-gated organic field effect transistor. Application to Cu²⁺ detection

Area of Science:

• Analytical Chemistry
• Materials Science
• Biotechnology

Background:

• Accurate detection of copper ions (Cu²⁺) in aqueous environments is crucial for environmental monitoring and biological studies.
• Existing methods for Cu²⁺ detection often face challenges with selectivity, sensitivity, or complex sample preparation.
• Electrolyte-gated organic field-effect transistors (EGOFETs) offer potential for sensitive biosensing applications due to their high charge carrier mobility and low operating voltage.

Purpose of the Study:

• To develop a novel sensor for selective and sensitive detection of Cu²⁺ in water.
• To functionalize an EGOFET gate electrode with a Gly-Gly-His (GGH) peptide probe for Cu²⁺ recognition.
• To demonstrate the transduction of Cu²⁺ complexation into a measurable electrical signal by the GGH-functionalized EGOFET.

Main Methods:

• Immobilization of the Gly-Gly-His (GGH) peptide probe onto the EGOFET gate electrode via electrooxidation.
• Electrochemical characterization of Cu²⁺ complexation with the immobilized GGH probe using cyclic and square wave voltammetries.
• Electrical characterization of the GGH-functionalized EGOFET response to varying Cu²⁺ concentrations, monitoring threshold voltage shifts and drain current changes.

Main Results:

• Successful electrochemical evidence of Cu²⁺ complexation by the grafted GGH peptide.
• Demonstration that GGH-functionalized EGOFETs effectively transduce Cu²⁺ binding events.
• Achieved a limit of detection (LOD) of approximately 10^-12 M for Cu²⁺.
• Observed a sensitivity of 1 µA dec^-1 in the linear detection range of 10^-12 M to 10^-8 M.

Conclusions:

• The GGH-peptide-functionalized EGOFET is a highly sensitive and selective platform for Cu²⁺ detection in water.
• This approach offers a promising low-cost, label-free method for real-time monitoring of copper ions.
• The developed sensor technology has significant potential for environmental and biomedical applications requiring trace metal analysis.