Scaling laws in confined media applied for biomarker detection

Biological processes often imply dynamics in crowded or confined media. Here, we focus on the entry of molecules into nanopores relevant for applications in health, biotechnologies, or the environment. Polymers in the so-called semi-dilute regime that are excluded from the nanopore generate pressure, allowing controlled entry of analytes and facilitating their detection and identification inside a confined media. In the first example, we use solid-state nanopores to study the entry dynamics of neutral polymers in a semi-dilute solution at the single-molecule level. We investigate the influence of polymer concentration, chain length and nanopore size. In the second example, we study the detection and identification of polysaccharides of various molecular weights in the presence of large polymers. The third example, discriminates between two peptide biomarkers with an enantiomeric difference in only one amino acid (D- or L-) for different stoichiometric ratios. From these examples, we experimentally demonstrate the universal behavior that drives large polymers into a nanopore. When the mesh size of the semi-dilute solution is smaller than the nanopore size, the osmotic energy overcomes the confinement energy, allowing the chain to enter the confined media. The necessary threshold concentration required for polymer entry and transport we found that the power-law dependency of the ratio between nanopore size and monomer size is predicted theoretically by Pierre-Gilles de Gennes. Additionally, we found that the depletion layer thickness depends on the screening length (mesh size). We show three regimes that rely on the ratio between the pore size and the screening length. The application of polymer scaling laws represents a universal approach to control the dynamics of biomolecules through nanopores. Raw data used in the publication "Scaling laws in confined media applied for biomarker detection" by Yuhua Cai, Benjamin Cressiot, Mathias Winterhalter, Sébastien Balme, Juan Pelta, Laurent Bacri