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dc.contributor.author
Huber, Rebecca P.
dc.contributor.supervisor
Spencer, Nicholas
dc.contributor.supervisor
Maniura, Katharina
dc.contributor.supervisor
Berner, Simon
dc.contributor.supervisor
Vörös, Janos
dc.date.accessioned
2018-06-13T13:56:20Z
dc.date.available
2018-06-13T12:59:32Z
dc.date.available
2018-06-13T13:56:20Z
dc.date.issued
2018
dc.identifier.uri
http://hdl.handle.net/20.500.11850/269701
dc.identifier.doi
10.3929/ethz-b-000269701
dc.description.abstract
Gradient surfaces with a continuously changing surface parameter allow rapid, high-throughput investigations and systematic studies in tribology, adhesion and biology. Surface roughness is an important surface parameter on both micrometer and nanometer scales. In this thesis, different methods for the fabrication of micro- and/or nano-featured morphology gradients and their applications in biology are described. Nanoparticle-density gradients were produced by a simple dip-coating process of a positively charged poly(ethylene imine) (PEI)-coated silicon wafer into a negatively charged silica-nanoparticle suspension. To ensure firm anchoring of the particles to the surface the gradients were sintered at 1050 °C. All fabricated gradients were extensively characterized by SEM and AFM. Gradients were coated with TiO2 to mimic the surface of bone implants. A step-by-step in vivo like model that follows the natural processes occurring after implantation of an osseous implant was chosen to study the effect of nano-rough surfaces on protein adsorption, blood coagulation as well as cell behavior. TiO2-coated nanoparticle-density gradients were used for protein-adsorption studies. For gradients with 39- and 72-nm-diameter nanoparticles no influence of nano-features on the amount of adsorbed proteins could be found. In contrast, for gradients with 12-nm-diameter nanoparticles, fibrinogen in competition with albumin and fibronectin or serum, showed a higher adsorption at the high-particle-density end of the gradient. Blood-coagulation studies revealed that nanostructures involving 39-nm-diameter nanoparticles seem to enhance blood coagulation. With an increase in 39 nm particle-density, faster fibrin-network formation was observed, while smaller (12 nm) and bigger (72 nm) nanoparticles did not influence the activation of platelets or the fibrin-network formation. Monoclonal-antibody binding specific for the dodecapeptide sequence of the fibrinogen γ chain was measured on fibrinogen adsorbed onto nanoparticle-density gradients to gain further insight into the correlation between the protein and blood experiments. The ratio of antibody to adsorbed fibrinogen decreased by approximately 65% with increasing nanoparticle density for 39 nm particles, indicating conformational changes of adsorbed fibrinogen along the gradient. Human-bone-cell (HBC) experiments performed on nano-roughness gradients exhibited a gradual change in the cell behavior along the gradient with decreasing proliferation with decreasing inter-particle distance. Ten days post seeding, the number of HBCs on 39 nm particle-density gradients was six times higher at positions without particles compared to the high-density end of the gradient. Since biological experiments require a large number of substrates, different replication techniques were used to create copies of master gradients. Injection molding from polymer inserts was shown to be a successful replication technique for the mass production of samples with 72 nm features. For smaller nanoparticle, a novel replication method called substrate conformal imprint lithography (SCIL) demonstrated the replication of nanofeatures down to a size of 12 nm and was proven to be able to replicate combined nano- and micro-featured structures. Lastly, silver-particle gradients with changing particle size, height and density along the gradient were prepared by dewetting of gradients in silver thickness. Replication of the silver-particle gradients in PDMS and epoxy was shown to be a possible way to produce identical particle-size gradients and TiO2 coated epoxy replicas could be used for biological applications.
en_US
dc.format
application/pdf
en_US
dc.language.iso
en
en_US
dc.publisher
ETH Zurich
en_US
dc.rights.uri
http://rightsstatements.org/page/InC-NC/1.0/
dc.title
Morphological Gradients for Protein-Adsorption and Blood-Coagulation Studies
en_US
dc.type
Doctoral Thesis
dc.rights.license
In Copyright - Non-Commercial Use Permitted
ethz.size
250 p.
en_US
ethz.code.ddc
DDC - DDC::6 - Technology, medicine and applied sciences::610 - Medical sciences, medicine
ethz.code.ddc
DDC - DDC::5 - Science::570 - Life sciences
ethz.identifier.diss
25057
en_US
ethz.publication.place
Zurich
en_US
ethz.publication.status
published
en_US
ethz.leitzahl
ETH Zürich::00002 - ETH Zürich::00012 - Lehre und Forschung::00007 - Departemente::02160 - Dep. Materialwissenschaft / Dep. of Materials::02646 - Institut für Polymere / Institute of Polymers::03389 - Spencer, Nicholas / Spencer, Nicholas
en_US
ethz.date.deposited
2018-06-13T12:59:33Z
ethz.source
FORM
ethz.eth
yes
en_US
ethz.availability
Open access
en_US
ethz.rosetta.installDate
2018-06-13T13:59:25Z
ethz.rosetta.lastUpdated
2020-02-15T13:32:06Z
ethz.rosetta.versionExported
true
ethz.COinS
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