Ultra-sensitive Digital Molecular and Viral Assays for Point of Care Diagnosis Using Photonic Crystal Biosensor Microscopy
Brian Cunningham,
Donald Biggar Willett Professor in Engineering,
University of Illinois at Urbana-Champaign
By combining biosensor microscopy that provides high contrast for detecting individual biomolecules and viruses with novel biochemistry methods that can effectively turn each target molecule into many digitally-counted sensing events, it is possible to achieve attomolar-scale limits of detection for cancer-specific nucleic acid target molecules (miRNA and ctDNA) while simultaneously obtaining thousands-to-one selectivity against single base variants. The presentation will describe the use of photonic metamaterials and associated detection instruments to amplify optical absorption and fluorescence emission. The biodetection technology platforms are used to perform assays using nucleic acid strand displacement reactions and CRISPR/Cas chemistry to sense target biomarkers from complex media. We also utilize DNA origami probes in the shape of hand-like “nano-grippers” that selectively recognize and bind with the outer surface proteins of viruses. The “amplify-then-digitize” approach represents a new and powerful paradigm for molecular and viral diagnostics, compared to the “digitize-then-amplify” approach utilized in methods such as droplet digital PCR (ddPCR). Overall, we seek simple, rapid, room temperature, single-step assay methods that can be operate with small, inexpensive, and robust detection systems for applications in point of care diagnostics, laboratory-based diagnostics, and life science research applications.
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