Meniscus-Directed Assembly of Biologically Active Coatings of Cells, Microparticles, and Nanoparticles
No Thumbnail Available
Files
Date
2009-04-23
Authors
Journal Title
Series/Report No.
Journal ISSN
Volume Title
Publisher
Abstract
Convective assembly principles and techniques were used in two complementary
studies for depositing close packed yeast-coated surfaces and gold nanoparticle wires.
Convective assembly at high volume fraction was used for the rapid deposition of
uniform, close-packed coatings of Saccharomyces cerevisiae onto glass slides. A
computational model was developed to calculate the thickness profiles of such coatings
for various experimental conditions. Both experimentation and numerical simulations
demonstrated that the deposition process is strongly affected by the presence of
sedimentation. The deposition device was inclined to increase the uniformity of the
coatings by causing the cells to sediment toward the three-phase contact line. In
accordance with the simulation, the experiments showed that both increasing the angle of
the device and decreasing the angle between the slides increased the uniformity of the
deposited coatings. Finally, the “convective-sedimentation†assembly method was used
to deposit composite coatings of live cells and large latex particles as an example of
biologically active composite coatings. These coatings were allowed to proliferate and
demonstrate a proof-of-concept of a self-cleaning surface.
Two methods were developed for the deposition of micro- and nanoparticles into
linear assemblies that could be used in biosensors and biomaterials. In capillary-guided
deposition, a capillary is withdrawn across a wettable substrate, resulting in the assembly
of a particle line. We characterized the effects of particle concentration and withdrawal
speed and correlated them to structure of the deposited assemblies. The particles are
assembled into one of three different structures, depending on the particle volume
fraction and deposition speed. We demonstrate that the metallic nanoparticle lines are
Ohmically conductive. Using wedge-templated deposition, linear assemblies were
deposited from sessile droplets on moderately hydrophobic surfaces. The particles
convectively assemble at the freely-receding three-phase contact line and are pulled into a
line against the wedge. The deposited lines can be long and narrow with a few breaks or
significantly wider and shorter but unbroken. These methods could be used for
engineered patterning of nanoparticle structures on surfaces.
Description
Keywords
nanoparticle, cell coating, colloid
Citation
Degree
PhD
Discipline
Chemical Engineering
