Enzyme-polyelectrolyte multilayer assemblies on reduced graphene oxide field-effect transistors for biosensing...

Area of Science:

• Materials Science
• Nanotechnology
• Biotechnology

Background:

• Graphene-based field-effect transistors (FETs) offer high sensitivity for biosensing applications.
• Urea detection is crucial in medical diagnostics and environmental monitoring.
• Layer-by-layer (LbL) assembly provides a versatile method for surface functionalization.

Purpose of the Study:

• To develop a novel biosensor for urea detection using reduced graphene-oxide field-effect transistors (rGO FETs).
• To investigate the enhanced performance of rGO FETs modified with polyethylenimine and urease.
• To demonstrate the simultaneous detection of urea and heavy metals using the developed platform.

Main Methods:

• Fabrication of rGO FETs with an interdigitated microchannel.
• LbL assembly of polyethylenimine and urease onto rGO FETs.
• Exploitation of pH dependency of liquid-gated transistors and urease-catalyzed urea hydrolysis.
• Urease inhibition for heavy metal quantification.

Main Results:

• rGO FETs exhibited high pH sensitivity (20.3µA/pH) and transconductance up to 800 µS.
• The biosensor detected urea in the range of 1-1000µm with a limit of detection (LOD) down to 1µm.
• Urea detection performance improved with increased LbL bilayers.
• Quantification of Cu²⁺ with a LOD down to 10nM was achieved via urease inhibition.

Conclusions:

• The developed rGO FET-based biosensor is a versatile and sensitive platform for urea detection.
• The LbL assembly strategy enhances sensor performance and stability.
• The platform demonstrates potential for simultaneous detection of urea and heavy metals.