Detecting and measuring analytes or organisms in a mixed solution is needed in numerous applications such as flow cytometry, DNA sequencing, sensing of protein folding, sub-structural analysis, drug binding or vesicle sizing. Techniques for such applications are often limited by speed, accuracy, sample size as well as the need for secondary stains or labels. Direct assay of very small objects in their native state, especially in a mixed solution, needs a better solution.
Researchers at the University of California, Riverside can discriminate between mixed populations of cells and particles in solution using pressure to displace objects across a nanopore multiple times. Ionic current flow through the nanopore indicates the pressure required to translocate the object in the pore, which correlates to the object’s mass and volume. Key to these results is that a nanopore sensor allows pressure oscillations to capture and release repeatedly the same object to learn about its inertia and morphology. Such data can provide details about the size and shape of analytes, their morphologies and structural constraints, or even pathological conditions of living cells.
Fig. 1 Nanopore sensing of differently sized cells in a mixed bacterial culture.