title: Cell membrane conformation at vertical nanowire array interface revealed by fluorescence imaging.
abstract: The perspectives offered by vertical arrays of nanowires for biosensing applications in living cells depend on the access of individual nanowires to the cell interior. Recent results on electrical access and molecular delivery suggest that direct access is not always obtained. Here, we present a generic approach to directly visualize the membrane conformation of living cells interfaced with nanowire arrays, with single nanowire resolution. The method combines confocal z-stack imaging with an optimized cell membrane labelling strategy which was applied to HEK293 cells interfaced with 2-11 μm long and 3-7 μm spaced nanowires with various surface coatings (bare, aminosilane-coated or polyethyleneimine-coated indium arsenide). We demonstrate that, for all commonly used nanowire lengths, spacings and surface coatings, nanowires generally remain enclosed in a membrane compartment, and are thereby not in direct contact with the cell interior.
authors.affiliation: Bionanotechnology and Nanomedicine Laboratory, Department of Chemistry and Nano-science Center, University of Copenhagen, Universitetsparken 5, DK-2100, Copenhagen, Denmark.
authors.forename: Trine
authors.initials: T
authors.lastname: Berthing
authors.forename: Sara
authors.initials: S
authors.lastname: Bonde
authors.forename: Katrine R
authors.initials: KR
authors.lastname: Rostgaard
authors.forename: Morten Hannibal
authors.initials: MH
authors.lastname: Madsen
authors.forename: Claus B
authors.initials: CB
authors.lastname: Sørensen
authors.forename: Jesper
authors.initials: J
authors.lastname: Nygård
authors.forename: Karen L
authors.initials: KL
authors.lastname: Martinez
mesh_terms: D001152:Arsenicals / Q000737:chemistry; D002462:Cell Membrane / Q000648:ultrastructure*; D057809:HEK293 Cells; D006801:Humans; D007204:Indium / Q000737:chemistry; D018613:Microscopy, Confocal; D053770:Nanowires / Q000032:analysis*; D061848:Optical Imaging / Q000379:methods*; D011094:Polyethyleneimine / Q000737:chemistry; D012821:Silanes / Q000737:chemistry; D046888:Tissue Array Analysis
chemical_list: D001152:Arsenicals; D012821:Silanes; D007204:Indium; D011094:Polyethyleneimine; C076773:indium arsenide