Transcript Slide 1

Polypeptides
Hydrophobins
Stackers
Janus
Arborols
Bubbles =
MagnaChain-LC
Expt/Sim
Polycolloid
Magnaphase
hydrophobin-stabilized cylindrical bubbles
*pH, salt, temp, gases, pressure
*persistence length by digital microscopy
*size distribution by Nanosight & SLS/DLS
*SAXS, cryo-TEM and FFTEM for wall thickness
*Particles that adhere
*stabilization
*liquid crystallinity/directed transport
Responsive
3.25
3.20
3.15
 / ppm
Saturn
*Dilutability
*Inhibitor micelles
*Inhibition
*SADLCǂ
*Tunnels
3.10
3.05
3.00
2.95
Muscle
2.90
10
20
30
40
50
T/ °C
*ǂSelf-assembly driven liquid crystals
Star Rods
Aerocrystals
Porphyrins
SAPROD
Blob =
Surfactant-assisted Processing of Rods
Probe
SAD-ColCryst =
Onion
Self-Assembly Driven Col.Crys.
*Dilutability
*Micelle typeStackers
*Inhibition
*Tunnels
*Applications: photodynamic
cancer therapy (Vicente) or
light harvesting
hydrophobin-stabilized oil blobs
*oil spill cleanup
*solvent entrapment
*monomer entrapment/polymerization
*mesogen entrapment
*lyotropic LC entrapment/optical devices
*magnet entrapment
*dried to directed/rough surfaces
Rigatoni
SANCC
LabJack
=Self-Annealing ColCryst
PEGL
Char/DvsC/CUBubbleComposite
Conifer
MACE
Pouch
Jamming
SADLC =
Methods Development
MADLS
*Everyday use
*Ergonomics
*Research-grade
Holo-FPR
Self-Assembly Driven LC
Propellerhead
CCC=
Conc-Conf-Coupling
LBL via Click
Cowlick
OPTICAL MICROSCOPY
*LED FPR
*Particle tracking
*MSFCS
*Video FPR
SAXS
*Summed runs
*Flow cell
*Svergun software
TEM
*FF/TEM
*Cryo
Words
Measure nothing first, measure something unimportant next.
More, bolder, faster. --Frank Karasz
*Making better molecules.
*Mixed polyelectrolytes
*Holo-FPR/Shortscale PE
Policies
Help teammates.
Master’s, then Ph.D.
Seek internal review.
Gutsy mistakes can usually be fixed,
fretfully doing nothing cannot.
Only the inquisitive need join.
Pyramid Scheme
Watch your thoughts, they become your words.
Watch your words, they become your actions.
Watch your actions, they become your habits. –Freeman Hrabowski
Legend to Motivating Themes
Publish & Graduate
Do the right thing—it will gratify some people and astonish the rest. –Mark Twain
Create
Collaborators
Existing: Vicente, Zhang, Negulescu, Daly, Nesterov, F. Hung (ChE), Z. Liu (RNR),
Q. Wu (RNR)
Polyelectrolytes
Physical Insight
DIM (Disease-Inspired Material)
Build
Indulge Curiosity
Serve
Wonder
Discover
Have Fun
Synthetic/Preparative
Solve
Imagine
Janus fuzzballs
Janus was the Roman god of gates,
doors, doorways, beginnings, endings
and time. He had two faces,
sometimes different, looking in both
directions. The idea here is to make a
submicron particle which has one side
coated with polypeptide and the other
side coated with something else, or
uncoated at all.
We think these particles will be good
for applications like controlled surface
chemistry (hydrophobic or hydrophilic,
switchable) or capture/delivery of
chiral molecules. For example, the
polypeptide face could be oriented to
capture a chiral molecule from
solution and then spun around to
deliver it into a different phase.
The closest we have come to making a
Janus fuzzball was the work of Erick
Soto-Cantu, who managed to get one
side of a silica particle coated with
gold and the other coated with silica.
Placement of an azide coupling agent
on the silica side followed by click
reaction with an alkyne-initiated
polypeptide should produce the
desired particle.
Currently
investigated by
Cornelia Rosu of
Romania
Janus car!
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Magnachain
Some fuzzballs are equipped with a
superparamagnetic* nougat. This
enables them to exhibit magnetism
but only in the presence of an
applied field. So….when a magnetic
field is applied, each particle
develops a “north” and a “south”
pole. These are attracted to each
other, resulting in chains.
Currently
investigated by
Cornelia Rosu of
Romania
Applications of this include viscosity
modification (magnetorheological
effect, found in shock absorbers in
expensive luxury and sports cars)
and optical polishing (long story).
Our interest is trying to link the
fuzzballs together once they are
aligned. Then, taking advantage of
the ability of polypeptides to
expand and contract in response to
temperature and pressure (and
maybe one day light) we hope to
expand and contract the chain, like
muscle.
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Jamming
Currently studied by
Melissa Collins of
Louisiana
This is one of our most intricate and subtle projects. When particles bearing surface groups that can be
extended rods but which can also be floppy random coils are jammed together by magnetic attraction, will
the polymers choose the rodlike conformation in order to form “local liquid crystals” at the interfaces? If
so, then we have coupled a magnetic field to a molecular (and optical) transformation.
The very notion of a local liquid crystal was motivated by the observation of former student Jianhong Qiu
that particles jammed together in good solvents for the shell polymers remained stuck to each other, while
selecting a poor solvent for the shell resulted only in transient adhesion of the chained assembly of
particles.
The hypothesis that a local liquid crystal is involved is tested with small-and wide-angle X-ray scattering.
The overall stability of the polypeptide-coated particles is being developed, too—for example, by dynamic
light scattering measurements at modest concentrations.
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Probe Diffusion/Microrheology
Currently studied by
Melissa Collins of
Louisiana
Did you ever wonder what it would be like to ride around on a molecule? How do particles see polymers in
solution. We don’t know, but it’s really important because all sorts of particles from paints to proteins are
dispersed with polymers. Suppose they are carrying drugs, trying to deliver them to the inside of a cell.
How fast will they be able to go? Or, suppose you are trying to measure the viscosity of fluid inside a living
cell, or the viscosity of supercritical CO2 (considered a “green” solvent compared to some organic liqiuds,
despite release of CO2 to the atmosphere after evaporation). Well, you can just measure the speed of
diffusion of some probe particle through the solution and back out the viscosity.
Current research focuses on using polypeptide-coated spheres, whose surface can be altered. For example,
can we have a particle diffuse around inside a living system, then undergo helix-to-coil transition to “latch
onto” materials in the cell?
We use dynamic light scattering and other methods to measure the probe speed.
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Stackers
Stackers are molecules that lay on top
of each other to make a very long
fiber. We study two basic kinds:
porphyrins (with help from Prof.
Vicente) and arborols. Both have a
molecular weight of about 1000
g/mol—pretty small by our standards.
The porphyrins are macrocycles, while
the arborols assume the shape of a
dumb-bell.
Currently studied by
Javoris Hollingsworth
of Georgia
and ChE undergrad Mohammed Abu Laban
The porphyrins can capture light. One
of their main uses is photodynamic
therapy—shine a light on them to
release a drug. The arborols make
great model systems for amyloid
fibrils; we also hope to use them to
force a solution containing rodlike
polymers to switch into a liquid
crystalline phase. This would let
polymer liquid crystals perform
certain sensing and possibly display
applications.
Multiple methods are used to
understand Stackers. At right, results
from small-angle X-ray scattering and
cryo-transmission
electron
microscopy.
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Hydrophobins
The protein Cerato ulmin is one of nature’s most
powerful surfactants. Produced by fungi, cerato ulmin
and related proteins have been in the oceans for eons.
Elm afflicted with Dutch elm
disease
Cerato ulmin rod-shaped bubbles.
http://www.invasive.org/images/768x512/0355036.jpg
Mostly known for its toxicity to
elm trees, yet safe to animals,
cerato ulmin encapsulates air and
oil
in
unusual
cylindrical
structures having remarkable
stability. Very small quantities are
required.
Model of a comparable protein; note
green hydrophobic and gray hydrophilic
regimes. 
Oil-filled bubble can be
moved using optical tweezers.
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Tree: http://www.iwight.com/living_here/planning/images/DutchElmDisease01.jpg
http://cims.hispanictips.com/uploads/2008/03/sickle-cell-picture.jpg