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Substrate Microstructure Influences Properties of Poly(ethylene glycol) Monolayers on Au
KTH, Superseded Departments, Physics.
KTH, Superseded Departments, Physics.ORCID iD: 0000-0001-8534-6577
(English)In: Nano Letters, ISSN 1530-6992Article in journal (Other academic) Submitted
National Category
Physical Sciences
URN: urn:nbn:se:kth:diva-8846OAI: diva2:14310
QC 20101008Available from: 2005-12-02 Created: 2005-12-02 Last updated: 2010-10-08Bibliographically approved
In thesis
1. Nanometer Scale Protein Templates for Bionanotechnology Applications
Open this publication in new window or tab >>Nanometer Scale Protein Templates for Bionanotechnology Applications
2005 (English)Doctoral thesis, comprehensive summary (Other scientific)
Abstract [en]

Nanofabrication techniques were used to manufacture nanometer scale protein templates. The fabrication approach employs electron beam lithography (EBL) patterning on poly(ethylene glycol) (PEG) thiol (CH3O(CH2CH2O)17NHCO(CH2)2SH) self-assembled monolayers (SAM) on Au. The PEG SAM prevented protein surface adhesion and binding sites for protein were created in the SAM by EBL. Subsequent to EBL, the patterns in the PEG SAM were backfilled with 40-nm NeutrAvidin-coated fluorescent spheres (FluoSpheres). The spontaneous and directed immobilization of the spheres from a solution to the patterns resulted in high resolution protein patterns. The FluoSpheres could be arranged in any arbitrary pattern with ultimately only one or a few FluoSpheres at each binding site.

Growth dynamics and SAM morphology of PEG on Au were studied by atomic force microscopy (AFM). PEG SAMs on three types of Au with different microstructure were examined: thermally evaporated granular Au and two types of Au films produced by hydrogen flame annealing of granular Au, Au(111) and "terraced" Au (crystal orientation unknown). The different Au surfaces' substructure affected the morphology and mechanical properties of the PEG SAM. On Au(111), AFM imaging revealed monolayer formation through three distinct steps: island nucleation, island growth, and coalescence. The fine-structure of the SAM revealed dendritic island formation - an observation which can be explained by attractive intermolecular interactions and diffusion-limited aggregation. Island growth was not observed on the "terraced" Au.

AFM studies of EBL patterned PEG SAMs on Au(111) revealed two different patterning mechanisms. At low doses, the pattern formation occurs by SAM ablation in a self-developing process where the feature depth is directly dose dependent. At higher doses electron beam induced deposition of material, so-called contamination writing, is seen in the ablated areas of the SAM. The balance between these two mechanisms is shown to depend on the geometry of the pattern.

In addition to PEG SAMs, fibronectin monolayers on SiO2 surfaces were patterned by EBL. The areas exposed with EBL lose their functionality and do not bind anti-fibronectin. With this approach we constructed fibronectin templates and used them for cell studies demonstrating pattern dependent cell geometries and cell adhesion.

Place, publisher, year, edition, pages
Stockholm: KTH, 2005. xv, 108 p.
Trita-FYS, ISSN 0280-316X ; 2005:65
nanotechnology, bionanotechnology, nanobiotechnology, electron beam lithography, EBL, poly(ethylene glycol), PEG, self-assembled monolayer, SAM, self-immobilization, protein pattern
National Category
Physical Sciences
urn:nbn:se:kth:diva-530 (URN)91-7178-178-1 (ISBN)
Public defence
2005-12-09, FA32, AlbaNova, Roslagstullsbacken 21, Stockholm, 10:15
QC 20101008Available from: 2005-12-02 Created: 2005-12-02 Last updated: 2012-03-21Bibliographically approved

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