title: Insulated conducting cantilevered nanotips and two-chamber recording system for high resolution ion sensing AFM.
abstract: Biological membranes contain ion channels, which are nanoscale pores allowing controlled ionic transport and mediating key biological functions underlying normal/abnormal living. Synthetic membranes with defined pores are being developed to control various processes, including filtration of pollutants, charge transport for energy storage, and separation of fluids and molecules. Although ionic transport (currents) can be measured with single channel resolution, imaging their structure and ionic currents simultaneously is difficult. Atomic force microscopy enables high resolution imaging of nanoscale structures and can be modified to measure ionic currents simultaneously. Moreover, the ionic currents can also be used to image structures. A simple method for fabricating conducting AFM cantilevers to image pore structures at high resolution is reported. Tungsten microwires with nanoscale tips are insulated except at the apex. This allows simultaneous imaging via cantilever deflections in normal AFM force feedback mode as well as measuring localized ionic currents. These novel probes measure ionic currents as small as picoampere while providing nanoscale spatial resolution surface topography and is suitable for measuring ionic currents and conductance of biological ion channels.
authors.affiliation: Department of Bioengineering, University of California, San Diego, La Jolla, CA 92093, USA.
authors.forename: Brian
authors.initials: B
authors.lastname: Meckes
authors.affiliation: 1] Department of Bioengineering, University of California, San Diego, La Jolla, CA 92093, USA [2] Department of Aerospace and Mechanical Engineering, University of California, San Diego, La Jolla, CA 92093, USA.
authors.forename: Fernando Teran
authors.initials: FT
authors.lastname: Arce
authors.affiliation: 1] Department of Aerospace and Mechanical Engineering, University of California, San Diego, La Jolla, CA 92093, USA [2] Materials Science and Engineering Program, University of California, San Diego, La Jolla, CA 92093.
authors.forename: Laura S
authors.initials: LS
authors.lastname: Connelly
authors.affiliation: 1] Department of Bioengineering, University of California, San Diego, La Jolla, CA 92093, USA [2] Department of Aerospace and Mechanical Engineering, University of California, San Diego, La Jolla, CA 92093, USA [3] Materials Science and Engineering Program, University of California, San Diego, La Jolla, CA 92093.
authors.forename: Ratnesh
authors.initials: R
authors.lastname: Lal
mesh_terms: D001692:Biological Transport; D002462:Cell Membrane / Q000648:ultrastructure*; D007473:Ion Channels / Q000648:ultrastructure; D007477:Ions / Q000737:chemistry; D018625:Microscopy, Atomic Force; D058608:Nanopores / Q000648:ultrastructure*
chemical_list: D007473:Ion Channels; D007477:Ions