Single-molecule nucleic acid interactions monitored on a label-free microcavity biosensor platform.

Area of Science:

• Biophysics
• Nanotechnology
• Analytical Chemistry

Background:

• Biosensing requires highly sensitive transducers for detecting molecular interactions.
• Optical microcavities offer label-free detection capabilities.
• Plasmonic enhancements can further boost sensitivity to the single-molecule level.

Purpose of the Study:

• To develop a biosensing platform with single-molecule sensitivity and specificity.
• To detect nucleic acid hybridization and small molecule interactions.
• To enable label-free, real-time monitoring of molecular binding kinetics.

Main Methods:

• Utilized optical microcavity sensors based on glass microspheres.
• Integrated gold nanorods for plasmonic enhancement.
• Employed whispering gallery modes for signal amplification.
• Detected hybridization of 8-mer oligonucleotides and small intercalating molecules.

Main Results:

• Achieved single-molecule sensitivity in detecting nucleic acid hybridization.
• Demonstrated label-free and selective detection of specific binding events.
• Confirmed single-molecule hybridization through detection of intercalating molecules.
• Discriminated between matched and mismatched DNA strands based on kinetics.

Conclusions:

• The developed platform provides unprecedented sensitivity for biosensing applications.
• Transient monitoring of molecular interactions enhances sensor longevity and data analysis.
• This approach mitigates the need for high-affinity binding, broadening applicability.