title: Weak hydrostatic forces in far-scanning ion conductance microscopy used to guide neuronal growth cones.
abstract: Scanning ion conductance microscopy (SICM) is currently used for high resolution topographic imaging of living cells. Recently, it has been also employed as a tool to deliver stimuli to the cells. In this work we have investigated the mechanical interaction occurring between the pipette tip and the sample during SICM operation. For the purpose, we have built a setup combining SICM with atomic force microscopy (AFM), where the AFM cantilever replaces the sample. Our data indicate that, operating in far-scanning mode with current decrease values below 2%, no force can be detected, provided that the level of the electrolyte filling the pipette is equal to that determined by the capillary tension. A filling level different from this value determines a hydrostatic pressure, a flux through the pipette tip and detectable forces, even in far-scanning mode. The absolute value of these forces depends on the pipette tip size. Therefore, a possible pitfall when using SICM for cell imaging is to imply zero-force working conditions. However the hydrostatic forces can be exploited in order to deliver weak mechanical stimuli and guide neuronal growth cones. Evidences of the effectiveness of this approach are herein given.
authors.affiliation: Dipartimento di Scienze Fisiologiche Università di Pisa, via S. Zeno 31, 56127 Pisa, Italy. marpell@dfb.unipi.it
authors.forename: Mario
authors.initials: M
authors.lastname: Pellegrino
authors.forename: Paolo
authors.initials: P
authors.lastname: Orsini
authors.forename: Monica
authors.initials: M
authors.lastname: Pellegrini
authors.forename: Paolo
authors.initials: P
authors.lastname: Baschieri
authors.forename: Franco
authors.initials: F
authors.lastname: Dinelli
authors.forename: Donatella
authors.initials: D
authors.lastname: Petracchi
authors.forename: Elisabetta
authors.initials: E
authors.lastname: Tognoni
authors.forename: Cesare
authors.initials: C
authors.lastname: Ascoli
mesh_terms: D000818:Animals; D004573:Electrolytes; D020439:Growth Cones / Q000502:physiology*; D006874:Hydrostatic Pressure; D007865:Leeches / Q000166:cytology; D018625:Microscopy, Atomic Force / Q000379:methods; D018613:Microscopy, Confocal / Q000379:methods; D009474:Neurons / Q000166:cytology*
chemical_list: D004573:Electrolytes