pH-Responsive Triplex DNA Nanoswitches: Surface Plasmon Resonance Platform for Bladder Cancer-Associated microRNAs

Area of Science:

• Biomedical Engineering
• Molecular Diagnostics
• Nanotechnology

Background:

• Bladder cancer (BC) recurrence necessitates frequent monitoring.
• Current diagnostic methods can be invasive or lack sensitivity.
• Biomarker microRNAs (miRNAs) show promise for early detection and monitoring.

Purpose of the Study:

• To develop an innovative, noninvasive biosensing platform for sequential detection of BC-related miRNAs.
• To utilize pH-responsive triplex DNA nanoswitches (TDNs) for enhanced miRNA detection.
• To establish a sensitive and specific method for distinguishing BC patients from healthy individuals.

Main Methods:

• A stepwise surface plasmon resonance (SPR) biosensing platform (TDNs-SPR assay) was designed.
• pH-responsive triplex DNA probes (switch A and switch B) were assembled on an SPR sensing interface.
• Reporter units (streptavidin-Au nanoparticles/biotinylated strands) were employed for signal amplification.
• pH-induced displacement at pH 5.0 (miR-183) and pH 8.3 (miR-155) enabled sequential detection.

Main Results:

• The TDNs-SPR assay achieved low detection limits: 0.57 pM for miR-183 and 0.83 pM for miR-155.
• The platform demonstrated quantitative correlation between reflectivity changes and miRNA concentrations.
• The method successfully distinguished bladder cancer patients from healthy individuals using urine samples.

Conclusions:

• The pH-responsive TDNs-SPR assay provides a versatile and noninvasive tool for precise biomarker analysis.
• This platform holds significant potential for sensitive detection of bladder cancer recurrence.
• The adaptable sensing strategy can be applied to detect other disease-associated miRNAs.