Ultra-sensitive DNA detection with single-base mismatch resolution using graded hollow-core optical microcavity...

Area of Science:

• Photonics and Biosensing
• Nanotechnology for Diagnostics
• Optical Microcavity Sensors

Background:

• Optical microcavities offer high sensitivity for detecting molecular interactions.
• Functionalization with nanoparticles can enhance biosensor performance.
• Real-time, label-free detection methods are crucial for sensitive diagnostics.

Purpose of the Study:

• To propose and demonstrate a graded hollow-core optical microcavity (GHCOM) for ultrasensitive DNA hybridization detection.
• To enhance light-matter interaction and biological binding using polyA-AuNPs.
• To achieve a very low limit of detection (LoD) and high specificity for DNA detection.

Main Methods:

• Fabrication of a GHCOM with a graded longitudinal shape and high Q factor (7.8 × 10^6).
• Functionalization of the GHCOM surface with polyadenylic acid-conjugated gold nanoparticles (PolyA-AuNPs).
• Excitation and spectral tracing of whispering gallery modes (WGMs) for real-time monitoring of DNA hybridization.

Main Results:

• Demonstrated DNA hybridization detection from 1 fM to 1 pM.
• Achieved a DNA biosensing sensitivity of 2.38 pm/lg fM.
• Obtained an ultra-low limit of detection (LoD) of approximately 583 aM.
• Successfully detected single-base mismatch in 19-base target DNA.

Conclusions:

• The PolyA-AuNPs functionalized GHCOM serves as a highly sensitive and specific label-free DNA biosensor.
• The graded cavity design enhances light-matter interaction for improved sensing.
• This robust biosensor holds significant potential for bioengineering and disease diagnosis applications.