Abstract

PCR-Free MicroRNA Quantification Based on Ion-Selective Nanoporous Membranes and Nanopores

Hsueh-Chia Chang, Bayer Professor of Engineering / Director, University of Notre Dame

We report an integrated biochip platform that can identify and quantify low copy numbers of microRNA biomarkers in a heterogeneous physiological sample like blood, saliva or urine. This quantification assay is done without PCR amplification, reporter labeling,  extensive off-chip pretreatment and expensive optical sensors.  Consequently, it does not introduce PCR/ligation bias and limits analyte loss during pretreatment.  The main components of the integrated biochips are nanoporous membranes and solid-state nanopores with pore radii smaller than the nm-scale Debye length. We use the ion concentration and charge polarization features of the ion-selective membranes to control the on-chip ionic strength, actuate pH by splitting water, lyse exosomes and isolate/concentrate the target molecules. The final nanopore sensor or sensor array utilizes surface modification and pore geometry to preferentially delay the translocation time of the target microRNAs to achieve single-molecule identification and quantification. The integrated chip achieves a translocation frequency (throughput) that is at least one hundred times higher than any literature or commercial nanopore technology.