title: Direct observation of gold nanoparticle assemblies with the porin MspA on mica.
abstract: The octameric porin MspA from Mycobacterium smegmatis is sufficiently stable to form a nonmembrane-supported stand-alone porin on mica surfaces. About 98% of all MspA octamers were found to stand upright on mica, with their periplasmic loop regions bound to the hydrophilic mica surface. Both, small (d = 3.7 nm) and large (d = 17 nm) gold nanoparticles bind to MspA, however, in different positions: small gold nanoparticles bind within the MspA pore, whereas the large gold nanoparticles bind to the upper region of MspA. These experiments demonstrate that gold nanoparticles can be positioned at different, well-defined distances from the underlying surface using the MspA pore as a template. These findings represent a significant step toward the use of electrically insulating stable proteins in combination with metal nanoparticles in nanodevices.
authors.affiliation: Department of Chemistry, Kansas State University, Manhattan, Kansas 66506-3701, USA.
authors.forename: Matthew T
authors.initials: MT
authors.lastname: Basel
authors.forename: Raj Kumar
authors.initials: RK
authors.lastname: Dani
authors.forename: Myungshim
authors.initials: M
authors.lastname: Kang
authors.forename: Mikhail
authors.initials: M
authors.lastname: Pavlenok
authors.forename: Viktor
authors.initials: V
authors.lastname: Chikan
authors.forename: Paul E
authors.initials: PE
authors.lastname: Smith
authors.forename: Michael
authors.initials: M
authors.lastname: Niederweis
authors.forename: Stefan H
authors.initials: SH
authors.lastname: Bossmann
mesh_terms: D000538:Aluminum Silicates / Q000737:chemistry*; D002021:Buffers; D006046:Gold / Q000737:chemistry / Q000378:metabolism*; D057927:Hydrophobic and Hydrophilic Interactions; D053768:Metal Nanoparticles / Q000737:chemistry*; D000432:Methanol / Q000737:chemistry; D008958:Models, Molecular; D020102:Mycobacterium smegmatis; D036103:Nanotechnology; D018272:Porins / Q000737:chemistry / Q000378:metabolism*; D011485:Protein Binding; D011487:Protein Conformation; D055550:Protein Stability; D013499:Surface Properties; D014867:Water / Q000737:chemistry
chemical_list: D000538:Aluminum Silicates; D002021:Buffers; D018272:Porins; C121838:mspA protein, Mycobacterium smegmatis; D014867:Water; D006046:Gold; C011934:mica; D000432:Methanol