The iNAPO Project: Biomimetic Nanopores for a New Generation of Lab-on-Chip Micro Sensors

Abstract

In nature, ion conducting nanopores play a vital role for the function of living cells. They undergo gating processes where they open and close upon an external stimulus, such as the presence of a particular biomolecule, the ligand. When the gating process is observed and is quantitatively measured, one can derive data about the presence and the amount of the ligand. Hence, the nanopores can be utilized for specific sensing. However, biological nanopores are embedded in a biological cell membrane that is fragile and unstable with respect to storage and application. The iNAPO (ion conducting nanopores) project aims at combining robust polymer-based nanopores with protein-based biological nanopores, thus combining the selectivity and sensitivity of the latter with the stability and processibility of the first ones. This paper describes the different steps in the fabrication of ion conducting nanopores. It begins with ion irradiation of polymer foils, combined with chemical etching of the ion damage tracks into nanopores. By means of chemical coupling reactions, the nanopore walls are functionalized with particular molecules which react or bioconjugate with the molecules to be analyzed. As an example, a recent result on sensing a physiologically active phosphorus-based anion is shown. By means of a complexation reaction with Zn-di(picolyl)amine, the selective measurement of the concentration of the anion pyrophosphate is demonstrated. In the final step of the project, the nanopores will be incorporated into a Lab-on-Chip system for applications in e.g. medical diagnostics and environmental analysis.

Multiscale analysis of the effect of surface charge pattern on a nanopore’s rectification and selectivity properties: From all-atom model to Poisson-Nernst-Planck

“…Stimuli can be voltage, pH, molecules, ions, light, or temperature or combination of them. This makes nanopores promising candidates to be the core units of sensors [12,13,14,15,16,17,18]. Natural nanopores (called ion channels) play a crucial role in life due to their ability to facilitate controlled movement of ions through membranes separating cell compartments [19,20].…”

Development of a Biomolecular Analyzer Based on Ion-conducting Nanopores: The iNAPO Project

“…The ion damage track, a cylindrical linear zone through the polymer foil with reduced density and changed chemical composition, was etched in a NaOH solution into a conical pore with a large aperture of several 100 nanometers and a small one of a few nanometers diameter. The electrochemically controlled etch procedure has been described elsewhere [4]. Scanning Electron Micrographs of both apertures of a conical nanopore are shown in Fig.…”

“…Biological nanopores, however, are carried by the fragile lipid bilayer membrane that is not suitable for technical application and are, therefore, replaced by solid state nanopores [2,3]. The iNAPO project aims at fabricating nanopores in polymer foil, in a biomimetic approach, for use in biomedical sensing and analyzing devices [4]. In the iNAPO analyzer device, the ionic transport is measured electrochemically.…”

The effect of the charge pattern on the applicability of a nanopore as a sensor

“…This work was considerably inspired by the studies of Ensinger et al [22,23,24,25,26] who used conical PET nanopores with inherent rectification properties. Binding metal ions with functionalized surfaces changed the surface charge pattern on the nanopores' wall thus changing their conduction properties including rectification.…”