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2.  The term “dendrimer” is derived from the Greek
words “dendron” means tree or branches and
“meros” means part.
 It was introduced in 1984 by Donald A. Tomalia.

3.  Highly branched
macromolecule
 Capable of encapsulating
 High loading capacity
 Backbone of Carbons or
Nitrogens
 Monodisperse and
controllable
 Highly stable
 Low immunogenicity and
toxicity

4.  The structure is highly defined and organized.
 Dendrimers posses 3 distinguishing architectural
components:
1) Initiator core.
2) Interior layers.
3) Terminal functionalities.

5.  They start from a core molecule with at least 3
chemically reactive arms.
 To these arms, branches are attached.
- Repeated many time

6. •Branches extend from core to periphery.
•Large dendrimers adopt a globular shape, in
which all bonds converge to a focal point
•“Star Burst Effect”.

7.  Monodispersive.
 Exact same molecular weight and structure.
 Peculiar behaviour of intrinsic viscosity

8.  The terminal groups affect solubility and viscosity
 The outer surface area of the molecule increases with the number of
generations
 There are void space within the molecule.
 These unique geometries give the molecule special properties such as ability to
entrap foreign molecules (drugs).

9.  Two common delivery systems
1. Liposome 2. Polymers
 Poor stability
 Difficulty in targeting
 Toxicity
 Reduces circulation time

10. ENTANG L EMENTS
Dendrimers Linear Polymers
less entanglements more entanglement
.

11. Architecture
Dendrimers Linear Polymers
Dendritic architecture Linear architecture
has been shown as has not been shown
elegant, uniform, as elegant and can be
spherical and as visualized as
“green peas” “ cooked spaghetti”.
e.g. e.g Polyether linear
Polyether dendrimer. polymer

12. Size / Polydispersity
Dendrimers L inear Polymers
Have certain size, Does not have
monodisperse certain size and are , .
usually poly disperse.

13. Solubility
Dendrimers Linear Polymers
More solubility in Less soluble than
organic solvent in analogous dendrimer
comparison to the in organic solvent
analogous linear e.g. phenylene linear
polymer e.g. analogue.
1, 3, 5 phenylene
based dendrimer.

14. SYMMETRY
Dendrimers Hyper branched Polymers
Monodispersible regular P olydispersible , neither
and highly symmetrical. regular nor symmetrical.
SYNTHESIS
Obtained by careful , Obtained in a single step
stepwise growth of by poly condensation of
successive an A2B monomer.
generations.

15.  There are two defined methods of dendrimer
synthesis:
-Divergent
-Convergent growth approach.
 In the divergent method the molecule is
assembled from the core to the periphery.

16.  In the divergent method, the surface groups
initially are non-reactive or protected species which
are converted to reactive species for the next stage
of the reaction.
 In the convergent approach the opposite holds, as
the reactive species must be on the focal point of
dendritic wedge.

18. This type of synthesis involves two steps:
( 1 ) The activation of functional surface groups.
( 2 ) Addition of branching monomer units.

20. ADVANTAGE
 The advantage of this method is the ability to modify the
surface of the dendrimer molecule.

21.  In successive generation growth, side reactions and
incomplete additions become more apparent.
 This is due to steric hindrance.
 The overall yield is considerably small
 The outer generation has only one kind of functional
group.

22. •The difficulty of many reactions that have to be
performed on one molecule is overcome by
starting the synthesis at the periphery and ending
at the core.
•In this method, growth begins at what will
become the periphery of the final macromolecule
and proceed inward, the final reaction being
attachment to a polyfunctional core.

23.  It involves the attachment of the outermost functional group
to an inner generation and the attachment of the inner
generation to the core.
 The structural units before the final attachment to the core is
called the wedge.
 Usually 3 to 4 wedges attach to the core.
 Each wedge can have different functional groups at periphery.

25. Advantage of this method over “divergent growth”
approach :-
 control over surface functionality.
 Ease for purification.

26.  More susceptible to steric inhibition at the focal point
group.
 This effectively limits the size of the macromolecules
that may be prepared in conventional fashion.
.

28.  Convergent approach affords better control to obtain a better
dendrites architecture than the divergent approach.
 Divergent approach is for large scale production.
 Both involve stepwise processes that are tedious and time
consuming.

29.  The well-defined structure, compact globular shape, size monodispersity
and controllable „surface‟ functionalities of dendrimer makes them excellent
candidates for evaluation as drug carriers.
 They can be used as drug delivery agents in 2 ways
(1) Drugs molecules can be physically entrapped inside
the dentritic structure.
(2) Drug molecules can be covalently attached onto
surface or other functionalities to afford dendrimer
drug conjugates.

30.  The internal „cavity‟ of the dendritic structure can be
used for the entrapment drugs.
( I ) FIRST STRATEGY: -
First strategy for the encapsulation of the guest
molecules in dendrimers is physical encapsulation.

31.  Held by Van der
Waals or dipole
moments
 Carrier compounds
do not have to be
solublized

32. 1. Targeted delivery would be difficult to achieve because
drug release occurred by dialysis.
2. Difficult to make universal for all drugs, because
encapsulation by the dendrimer varied significantly
depending on drug and the dendrimer structure.

33.  The second strategy for the encapsulation of guest
molecules in dendrimers is based on multiple non-
covalent chemical interactions, such as hydrogen bonding
between guest molecules and dendritic structure.
 Sustained release is possible.

34.  The third and the most easily implemented startegy
for the encapsulation of drug molecules in
dendrimers is making use of hydrophobic
interactions
 Newkome et al. prepared dendritic macromolecules
with a hydrophobic interiors and hydrophilic chain
ends.
 These molecules were said to behave as unimolecular
micelles capable of solubilizing various hydrophobic

35.  e.g.:- Poly (aryl ether) dendrimers bearing
carboxylic groups as chain ends are able to
enhance the water solubility of the
hydrophobic compound such as pyrene and
anthracene.

36.  Higher generation dendrimers
have a greater number of end
groups that can be functionalized
 Longer retention time in blood –
PEG
 Targeting – ability to attach to
certain tissues or active sites
 Imaging – Fluorescence, MRI, or
X-ray

38. Applications in gene delivery

39. Dendrimers as Cancer Therapy
Therapeutic Cancer
agent detector
Reporter Cell death
monitor
Water Nanodevces
molecule

40. A single dendrimer can carry a molecule
that recognizes cancer cells,
A therapeutic agent to kill those cells,
A molecule that recognizes the signals
of cell death

41. YOU