Direct label free ultrasensitive impedimetric DNA biosensor using dendrimer functionalized GaN nanowires

Area of Science:

• Nanotechnology
• Biosensors
• Molecular Biology

Background:

• Label-free DNA detection is crucial for diagnostics.
• Existing methods often lack sensitivity or specificity.
• Gallium Nitride (GaN) nanowires offer unique electronic properties for sensing.

Purpose of the Study:

• To develop an ultrasensitive, label-free DNA biosensor.
• To functionalize GaN nanowires with poly(amidoamine)dendrimer (G3-PAMAM) for enhanced DNA immobilization.
• To demonstrate attomolar detection limits for target DNA hybridization.

Main Methods:

• Functionalization of GaN nanowires with G3-PAMAM.
• Covalent immobilization of probe DNA (p-DNA) onto the functionalized nanowires.
• Electrochemical impedance spectroscopy (EIS) for label-free detection of DNA hybridization.
• Comparative analysis of hybridization with complementary, mismatched, and irradiated target DNA (t-DNA).

Main Results:

• Achieved an ultra-high detection limit down to attomolar concentrations for complementary t-DNA.
• Demonstrated high selectivity and specificity against single/triple base-pair mismatched and γ-irradiated t-DNA.
• Observed significant, concentration-dependent changes in interfacial polarization resistance during hybridization.

Conclusions:

• The p-DNA/PAMAM/GaN NWs sensor probe is highly sensitive, specific, and reproducible.
• This novel methodology offers a robust platform for specific DNA sequence detection.
• The developed biosensor shows promise for various diagnostic applications.