Label-Free DNA Biosensor Using Modified Reduced Graphene Oxide Platform as a DNA Methylation Assay

Area of Science:

• Electrochemistry
• Nanomaterials Science
• Molecular Diagnostics

Background:

• DNA methylation assays are crucial for diagnosing diseases.
• Developing sensitive and label-free electrochemical biosensors is an active research area.
• Reduced graphene oxide (rGO) offers a promising platform for biosensor development due to its unique properties.

Purpose of the Study:

• To develop a modified reduced graphene oxide (rGO)-based electrochemical biosensor for label-free DNA methylation detection.
• To enhance biosensor sensitivity using nanoparticles (NPs) such as gold (AuNPs), silver (AgNPs), and copper (CuNPs).
• To evaluate the biosensor's potential as a diagnostic tool for DNA methylation assays.

Main Methods:

• Fabrication of rGO decorated with AuNPs, AgNPs, and CuNPs to increase electrode surface area.
• Hybridization of thiolated DNA probe (ssDNA-1) with target DNA sequence (ssDNA-2).
• Methylation of double-stranded DNA (dsDNA) using M.SssI methyltransferase (MTase) followed by HpaII endonuclease digestion.
• Monitoring MTase activity using differential pulse voltammetry (DPV).

Main Results:

• The rGO-AuNPs platform demonstrated the best performance for monitoring MTase activity.
• The developed biosensor is rapid, cost-effective, sensitive, selective, and highly specific.
• A low limit of detection (LOD) of 0.06 U·mL^-1 was achieved in buffer.
• An LOD of 0.19 U·mL^-1 was achieved using real serum samples.

Conclusions:

• Modified rGO, particularly rGO-AuNPs, serves as an effective platform for label-free electrochemical DNA biosensors.
• The developed biosensor shows significant potential for clinical diagnostics and DNA methylation assays.
• This approach can be adapted for the design of other advanced biosensing platforms.