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


7/28http://www3.interscience.wiley.com/cgi-bin/fulltext/106558159/PDFSTART

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/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.



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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/

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