title: Tuning the selectivity and sensitivity of an OmpG nanopore sensor by adjusting ligand tether length.
abstract: We have previously shown that a biotin ligand tethered to the rim of an OmpG nanopore can be used to detect biotin-binding proteins. Here, we investigate the effect of the length of the polyethylene glycol tether on the nanopore's sensitivity and selectivity. When the tether length was increased from 2 to 45 ethylene repeats, sensitivity decreased substantially for a neutral protein streptavidin and slightly for a positively charged protein (avidin). In addition, we found that two distinct avidin binding conformations were possible when using a long tether. These conformations were sensitive to the salt concentration and applied voltage. Finally, a longer tether resulted in reduced sensitivity due to slower association for a monoclonal anti-biotin antibody. Our results highlight the importance of electrostatic, electroosmotic and electrophoretic forces on nanopore binding kinetics and sensor readout.
authors: Molecular and Cellular Biology Program, University of Massachusetts Amherst, Amherst, MA 01003; Department of Chemistry, University of Massachusetts Amherst, Amherst, MA 01003.
authors: Monifa A
authors: MA
authors: Fahie
authors: Department of Chemistry, University of Massachusetts Amherst, Amherst, MA 01003.
authors: Bib
authors: B
authors: Yang
authors: Department of Chemistry, University of Massachusetts Amherst, Amherst, MA 01003.
authors: Bach
authors: B
authors: Pham
authors: Molecular and Cellular Biology Program, University of Massachusetts Amherst, Amherst, MA 01003; Department of Chemistry, University of Massachusetts Amherst, Amherst, MA 01003.
authors: Min
authors: M
authors: Chen
keywords: OmpG; antibody; biotin; nanopore; sensing; streptavidin