Thermally Switchable Nanogate Based on Polymer Phase Transition.

Mimicking and extending the gating properties of biological pores is of paramount interest for the fabrication of membranes that could be used in filtration or drug processing. Here, we build a selective and switchable nanopore for macromolecular cargo transport. Our approach exploits polymer graftings within artificial nanopores to control the translocation of biomolecules. To measure transport at the scale of individual biomolecules, we use fluorescence microscopy with a zero-mode waveguide set up. We show that grafting polymers that exhibit a lower critical solution temperature creates a toggle switch between an open and closed state of the nanopore depending on the temperature. We demonstrate tight control over the transport of DNA and viral capsids with a sharp transition (∼1 °C) and present a simple physical model that predicts key features of this transition. Our approach provides the potential for controllable and responsive nanopores in a range of applications.

Versatile transduction scheme based on electrolyte-gated organic field-effect transistor used as immunoassay readout system.

We report on an innovative heterogeneous bisphenol A (BPA) immunoassay based on an electrolyte-gated organic field-effect transistor whose organic semiconductor is poly(2,5-bis(3-tetradecylthiophen-2-yl)thieno[3,2-b]thiophene) co-crystallized with an alkyl derivative of bisphenol A. A decrease of the transistor output current is first observed upon antibody specific binding onto the organic semiconductor. Upon bisphenol A addition, the competitive dissociation of the antibody from the semiconductor surface leads to an opposite increase of the output current. We present here a proof-of-concept for bisphenol A detection; the device could be readily adapted to other small organic molecules of interest and is a promising tool for simple, low-cost, portable and easy-to-use biosensors.