Label-free quantification of molecular biomarkers using optical trapping assisted nanopore sensing (Invited Paper)

Integrated optofluidic nanopore sensor technologies have enabled label-free quantification of molecular biomarkers by digital detection of target biomolecules with the electrical translocation signal created during passage through a nanoscale opening. The approach utilizes planar waveguide-based optical trapping combined with a customized microfluidic channel geometry for million-fold target concentration enhancement underneath a nanopore. The optofluidic device design is optimized for better optical trapping performance utilizing both gradient and scattering optical forces. Combined with a target-specific bioassay, this simple, direct, and highly sensitive detection method enables amplification-free and calibration-free biomarker quantification. Using this platform, we show viral load day progression of Zika and SARS-CoV-2 infections from different biofluids in primate models across the clinically relevant concentrations range (five orders) down to 10 aM –comparable to and sometimes improving upon qRT-PCR results. We also report the use of this integrated sensor for extracellular vesicle cargo monitoring from cerebral organoids grown in conditioned media.