dendrimers (1)
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Dendrimers
NANO52
Foo th i l l Col lege
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Overview
What are dendrimers?
How are they formed?
What are their properties?
What are the applications?
How do you characterize them?
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http://www.chemistry.ohio-state.edu/cgi-bin/brochure?Faculty=parquett
Dendr imers Build ing B locks
of Nano techno logy
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Dendrimers consist of a series of chemical shells built on a
small core molecule. Each shell consists of two chemicals,
always in the same order and is called a generation
http://nano.med.umich.edu/Dendrimers.html#dendrimer_introduction http://www.ninger.com/dendrimer/
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http://www3.interscience.wiley.com/cgi-bin/fulltext/106558159/PDFSTART
Dendrimer Components
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Similarities
Size
Weight
Well defined chemical structure (knownbonding structure)
3 dimensional position of each atom is
difficult to determine - yet a consistent
specific 3 dimensional structure exists
Difficult to perform chemical analysis
Easy for cell to uptake
http://nano.med.umich.edu/Dendrimers.html
Main Difference
Proteins are polymers made
from 20 different monomers,
while dendrimers are polymers
made from two monomers.
Dendrimers vs. Proteins
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Light Harvesting Dendrimers
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Organic Light EmittingDiodes (OLEDs)
http://www3.interscience.wiley.com/cgi-bin/fulltext/106558159/PDFSTART
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Dendrimer Applications
"The future of dendritic
macromolecules lies in large
part with cleverly designed
syntheses that can deliver
the structures best-suited for
interesting applications,"Frchet says. "Our group is
deeply involved not only in
mission-oriented synthesis
but also in learning more
about the properties of
dendrimers that take fulladvantage of their precise
nanometer size, high
functionality, and regular
structural features."
This light-harvesting dendrimer performs some
functions of artificial photosynthesis. White light is
gathered through chain-ends that behave like antennae
and funneled into a chromophore in the dendrimer's
core that then emits a single color of amplified light
http :/ /www.lbl.gov /Science-Art ic les/Research-Review/Magazine/2001/Fall/features/02Dendrim ers.html
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Catalysis
http://perceco2.chem.upenn.edu/~percec/inthenews/denx.html http://www3.interscience.wiley.com/cgi-bin/fulltext/106558159/PDFSTART
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A schematic illustration of supramolecular architectures of self-assembled extended
amphiphilic dendrons, developed at Cornell by Ulrich Wiesner, professor of materials
science and engineering , and his research team. The illustration shows (A) cubic micelles,
(B) two-dimensional lamellar layers, (C) hexagonally arranged cylindrical columns and (D)
three-dimensional continuous cubic structures.
Cornell Center for Materials ResearchCopyright Cornell University
http://www.news.cornell.edu/releases/Sept04/Wiesner.supermolecules.deb.html
SupramolecularArchitectures
http://www.news.cornell.edu/Utilities/Copyright.htmlhttp://www.news.cornell.edu/Utilities/Copyright.htmlhttp://www.news.cornell.edu/photos/supermolecules300.jpg -
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Bio-TherapeuticDendrimers
http://www.fda.gov/nanotechnology/powerpoint_conversions/chbsa-nanotech-presentation06-05_files/images/image5.png
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The dendrimer (blue and red) attaches to multiple receptors
(pink) on cell membranes or other biological structures such
as a virus.
The dendrimers (blue and red) in VivaGel interact with
protein structures (yellow) on the surface of HIV, blocking
the interaction of HIV (purple) with healthy human cells
(pink) that results in HIV infection.
Illustrations courtesy of Starpharma Pooled Development, Ltd
http://www.smalltimes.com/document_display.cfm?document_id=6691
Dendrimers Fighting the Spread of Diseases
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Drug Delivery
http://www.davidwang.homestead.com/files/Drug_delivery.pdf
http://www.umich.edu/news/?Releases/2004/Mar04/r032304
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Dendrimer Conjugates
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Dendrimers
www.dendr i tch.com
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Dendrimer Generations
Dendrimers are synthesized in
generations, as shown in thisanimated graphic from Dendritech.
Poly(amido amine) (PAMAM)
dendrimers represent an exciting new
class of macromolecular architecture
called "dense star" polymers. Unlike
classical polymers, dendrimers have a
high degree of molecular uniformity,
narrow molecular weight distribution,specific size and shape
characteristics, and a highly-
functionalized terminal surface. The
manufacturing process is a series of
repetitive steps starting with a central
initiator core. Each subsequent growth
step represents a new "generation" ofpolymer with a larger molecular
diameter, twice the number of reactive
surface sites, and approximately
double the molecular weight of the
preceding generation.
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Dendrimers (Arborols)
Synthesis to 2ndg enerat ion A rbo rol - h ttp: / /en.wik ipedia.org /wik i /Dendr imer
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Dendrimers (Arborols)
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Dendrimer
Superstructures
Dendrimersare repetitivelybranchedmolecules. [1][2]The
name comes from the Greekword
"" (pronounced dendron),
which translates to "tree".
Synonymous terms for dendrimer
include arborolsand cascade
molecules. However, dendrimer is
currently the internationallyaccepted term. A dendrimer is
typically symmetric around the
core, and often adopts a spherical
three-dimensional morphology. The
word dendronis also encountered
frequently. A dendron usually
contains a single chemicallyaddressable group called the focal
point. The difference between
dendrons and dendrimers is
illustrated in figure one, but the
terms are typically encountered
interchangeably.[3]
http://www.gade.uni-hd.de/research.php
http://en.wikipedia.org/wiki/Branching_%28polymer_chemistry%29http://en.wikipedia.org/wiki/Moleculeshttp://en.wikipedia.org/wiki/Dendrimerhttp://en.wikipedia.org/wiki/Dendrimerhttp://en.wikipedia.org/wiki/Greek_languagehttp://en.wikipedia.org/wiki/Dendrimerhttp://en.wikipedia.org/wiki/Dendrimerhttp://en.wikipedia.org/wiki/Greek_languagehttp://en.wikipedia.org/wiki/Dendrimerhttp://en.wikipedia.org/wiki/Dendrimerhttp://en.wikipedia.org/wiki/Moleculeshttp://en.wikipedia.org/wiki/Branching_%28polymer_chemistry%29 -
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Bioactive Dendrimers
Dendrimers can be
functionalized for surfaceactivity., such as attaching
to cells, and using a
quantum dot interior core
for imaging. Dendrimers
can contain metal atoms
including gold which can
absorb radiation at a
particular wavelength, and
used in cancer treatment.
The relatively short lifetime
of a dendrimer enures thatit wont bioaccumulate in
the body, or concentrate
potentially toxic cadmium
(CdS quantum dots).
http://pubs.acs.org/doi/abs/10.1021/nl202220qand http:/ /www.ncbi.nlm.nih.gov/pubmed/21864902
http://pubs.acs.org/doi/abs/10.1021/nl202220qhttp://www.ncbi.nlm.nih.gov/pubmed/21864902http://www.ncbi.nlm.nih.gov/pubmed/21864902http://pubs.acs.org/doi/abs/10.1021/nl202220q -
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Gene Delivery via Dendrimer
The ability to deliver pieces of DNAto
the required parts of a cell includes
many challenges. Current research is
being performed to find ways to use
dendrimers to traffic genes into cells
without damaging or deactivating the
DNA. To maintain the activity of DNA
during dehydration, the dendrimer/DNA
complexes were encapsulated in a
water soluble polymer, and thendeposited on or sandwiched in
functional polymer films with a fast
degradation rate to mediate gene
transfection. Based on this method,
PAMAM dendrimer/DNA complexes
were used to encapsulate functional
biodegradable polymer films for
substratemediated gene delivery.
Research has shown that the fast
degrading functional polymer has great
potential for localized transfection.
http: / /en.wikipedia.org/wiki /Dendr imers
http://en.wikipedia.org/wiki/DNAhttp://en.wikipedia.org/wiki/Transfectionhttp://en.wikipedia.org/wiki/Transfectionhttp://en.wikipedia.org/wiki/DNA -
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Organic Synthesis
Dendrimers have been prepared via click
chemistry, employing Diels-Alder reactions,thiol-
yne reactions and azide-alkyne reactions.An
example is the synthesis of certain
polyphenylene dendrimers is shown in this
figure http: / /en.wik ipedia.org/wiki /Dend r imer
http://en.wikipedia.org/wiki/Click_chemistryhttp://en.wikipedia.org/wiki/Click_chemistryhttp://en.wikipedia.org/wiki/Diels-Alder_reactionhttp://en.wikipedia.org/wiki/Thiol-yne_reactionhttp://en.wikipedia.org/wiki/Thiol-yne_reactionhttp://en.wikipedia.org/wiki/Azide_alkyne_Huisgen_cycloadditionhttp://en.wikipedia.org/wiki/Azide_alkyne_Huisgen_cycloadditionhttp://en.wikipedia.org/wiki/Azide_alkyne_Huisgen_cycloadditionhttp://en.wikipedia.org/wiki/Azide_alkyne_Huisgen_cycloadditionhttp://en.wikipedia.org/wiki/Thiol-yne_reactionhttp://en.wikipedia.org/wiki/Thiol-yne_reactionhttp://en.wikipedia.org/wiki/Thiol-yne_reactionhttp://en.wikipedia.org/wiki/Diels-Alder_reactionhttp://en.wikipedia.org/wiki/Diels-Alder_reactionhttp://en.wikipedia.org/wiki/Diels-Alder_reactionhttp://en.wikipedia.org/wiki/Click_chemistryhttp://en.wikipedia.org/wiki/Click_chemistry -
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Divergent Synthesis
The dendrimer is assembled from a multifunctional core, which is extended
outward by a series of reactions, commonly a Michael reaction. Each step of
the reaction must be driven to full completion to prevent mistakes in thedendrimer, which can cause trailing generations (some branches are shorter
than the others). Such impurities can impact the functionality and symmetry of
the dendrimer, but are extremely difficult to purify out because the relative size
difference between perfect and imperfect dendrimers is very small.
http: / /en.wikipedia.org/wiki /Dendr imers
http://en.wikipedia.org/wiki/Michael_reactionhttp://en.wikipedia.org/wiki/Michael_reaction -
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Supramolecular
Dendrimers
Supramolecular systems arerarely designed from first
principles. Rather, chemists
have a range of well-studied
structural and functional
building blocks that they are
able to use to build up larger
functional architectures. Manyof these exist as whole families
of similar units, from which the
analog with the exact desired
properties can be chosen. The
molecule shown here is a
combination of traditionalorganic synthetic compounds
using significant steric
hinderence to achieve a
particular shape/conformation.
http: / /en.wikipedia.org/wiki /Dendr imers
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Summary
Dendrimers are branching structures
Multiple molecular/synthetic generations
Resemble macromolecules (proteins) Can have an active inner core
Related to supramolecular structures
Applications in medicine/ drug delivery
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References
Wikipedia (dendrimers)
Dendritech - http://www.dendritech.com/
NCBI => molecules and PubMed FDAwww.fda.gov
Institute for Molecular Manufacturing
(IMM)
http://www.dendritech.com/http://www.fda.gov/http://www.fda.gov/http://www.dendritech.com/