Fig. 1. Discrimination of FANA homopolymers via a static pore blockage. (A) The structure of 2′-deoxy-2′-fluoroarabinonucleic acid (FANA). (B) Schematic diagram of a static pore blockage event. A streptavidin molecule (purple sphere) is tethered to a piece of 3′-biotin (green triangle)-modified FANA. The FANA tethered in this way is electrophoretically driven into the MspA nanopore and held by streptavidin, generating a static, sequence dependent pore blockage current (pink region). (C) Representative pore blockage events from streptavidin-tethered FANA polyU (green), polyA (blue), and polyC (red) sequences. I_o, open pore ionic current; I_b, blocked ionic current. (D) Event statistics of I_b/I_o for different FANA homopolymers. Histogram peaks from different FANA homopolymers (polyU, green; polyA, blue; polyC, red) are Gaussian fitted. The experiments were carried out in the electrolyte buffered solution of 1 M KCl, 10 mM HEPES at pH 8.0.