title: Assembling Bare Au Nanoparticles at Positively Charged Templates.
abstract: In-situ X-ray reflectivity (XRR) and grazing incidence X-ray small-angle scattering (GISAXS) reveal that unfunctionalized (bare) gold nanoparticles (AuNP) spontaneously adsorb to a cationic lipid template formed by a Langmuir monolayer of DPTAP (1,2-dihexadecanoyl-3-trimethylammonium-propane) at vapor/aqueous interfaces. Analysis of the XRR yields the electron density profile across the charged-interfaces along the surface normal showing the AuNPs assemble with vertical thickness comparable to the particle size. The GISAXS analysis indicates that the adsorbed mono-particle layer exhibits short-range in-plane correlations. By contrast, single-stranded DNA-functionalized AuNPs, while attracted to the positively charged surface (more efficiently with the addition of salt to the solution), display less in-plane regular packing compared to bare AuNPs.
authors.affiliation: Division of Materials Sciences and Engineering, Ames Laboratory, USDOE, Ames, Iowa 50011, United States.
authors.forename: Wenjie
authors.initials: W
authors.lastname: Wang
authors.affiliation: Division of Materials Sciences and Engineering, Ames Laboratory, USDOE, Ames, Iowa 50011, United States.|Department of Materials Science and Engineering, Iowa State University, Ames, Iowa 50011, United States.
authors.forename: Honghu
authors.initials: H
authors.lastname: Zhang
authors.affiliation: X-ray Science Division, Advanced Photon Source, Argonne National Laboratory, Lemont, Illinois 60439, United States.
authors.forename: Ivan
authors.initials: I
authors.lastname: Kuzmenko
authors.affiliation: Division of Materials Sciences and Engineering, Ames Laboratory, USDOE, Ames, Iowa 50011, United States.|Department of Chemical and Biological Engineering, Iowa State University, Ames, Iowa 50011, United States.
authors.forename: Surya
authors.initials: S
authors.lastname: Mallapragada
authors.affiliation: Division of Materials Sciences and Engineering, Ames Laboratory, USDOE, Ames, Iowa 50011, United States.|Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011, United States.
authors.forename: David
authors.initials: D
authors.lastname: Vaknin