Ultrasensitive Label-Free Nucleic-Acid Biosensors Based on Bimodal Waveguide Interferometers

Area of Science:

• Biomedical Engineering
• Nanotechnology
• Biosensing

Background:

• The bimodal waveguide (BiMW) biosensor utilizes evanescent field detection for label-free biomolecular interaction analysis.
• Its ultrasensitivity allows for the detection of nucleic acids like mRNA and microRNA at attomolar-femtomolar concentrations.

Purpose of the Study:

• To describe the working principle and application of the BiMW biosensor for nucleic acid analysis.
• To demonstrate the utility of BiMW biosensors for cancer diagnosis using specific RNA biomarkers.

Main Methods:

• Fabrication of BiMW sensors using standard silicon microelectronics technology for miniaturization and cost-effectiveness.
• Functionalization of BiMW sensor surfaces with specific DNA probes for target hybridization.
• Real-time monitoring of light intensity changes to detect target nucleic acid hybridization.

Main Results:

• Detailed DNA functionalization procedures are presented.
• Successful analysis of mRNA transcripts from the Fas gene and miRNA 181a from urine liquid biopsies.
• Demonstrated potential for early bladder cancer diagnosis using miRNA detection.

Conclusions:

• The BiMW biosensor is a powerful, ultrasensitive tool for label-free nucleic acid detection.
• Its application in analyzing cancer-related RNA biomarkers shows promise for point-of-care diagnostics.
• The technology's compatibility with microelectronics fabrication supports portable and disposable sensing platforms.