Label-free, ultra-low detection limit DNA biosensor using high quality optical microcavity functionalized by DNA...

Area of Science:

• Nanotechnology
• Biomedical Engineering
• Optical Sensing

Background:

• Label-free DNA detection is crucial for medical diagnostics.
• Existing biosensors face limitations in sensitivity and probe density.
• Optical microcavities offer high sensitivity for molecular detection.

Purpose of the Study:

• To develop a novel label-free DNA biosensor with ultra-low detection limits.
• To functionalize an optical microcavity with 3D DNA nanostructures for enhanced DNA sensing.
• To demonstrate the superior performance of the proposed biosensor compared to traditional methods.

Main Methods:

• Fabrication of a high-quality optical microcavity with a hollow core and thin walls.
• Functionalization of the microcavity surface with self-assembled DNA tetrahedral nanostructure (DTN) probes.
• Excitation and tracing of whispering gallery mode (WGM) spectra for real-time DNA detection in a microfluidic channel.

Main Results:

• Achieved high efficiency binding of DTN probes to the sensor and target DNA.
• Demonstrated ultra-low limit of detection (LoD) for DNA, approximately 1000 times lower than with 1D probes.
• Maintained a high quality factor (Q > 10^7) for the optical microcavity.
• Utilized a small sample volume (nL) for detection.

Conclusions:

• The 3D DNA nanostructure functionalized optical microcavity enables highly sensitive, label-free DNA detection.
• Increased probe density and reduced probe entanglement contribute to the improved LoD.
• The biosensor shows significant potential for applications in bioengineering and medical diagnostics due to its sensitivity, real-time capability, and compact size.