2. DEFINITION
Aquasomes are nanoparticulate carrier system but
instead of being simple nanoparticles these are
three layered self assembled structures, comprised
of a solid phase nanocrystalline core coated with
oligomeric film to which biochemically active
molecules are adsorbed with or without
modification.
3. AQUASOMES
Aquasomes are first discovered by Nir
Kossovsky.
Aquasomes consists of solid crystalline core,
carbohydrate core &active drug
Aquasomes are spherical 60-300 nm
4. Aquasomes are also called as “bodies of water”
andtheir water like properties protect and preserve
fragile biological molecules,
This property of maintaining conformational
integrity as well as high degree of surfaexposure
made it as a successful carrier system for bioactive
molecules like peptide, protein, hormones, antigens
and genes to specific sites, that is for targeting.
5. METHODS OF PREPARATION OF
AQUASOMES
By using the principle of self assembly, the
aquasomes are prepared in three steps i.e.,
1. preparation of core,
2. coating of core, and
3. immobilization of drug molecule.
6. PRINCIPLE OF SELF ASSEMBLY
In aqueous biological environments , the assembly of
macro molecule Is governed by three process.
(1) Interaction between charged group.
(2) Hydrogen bonding and dehydration
(3) structural stability.
7. 1)INTERACTION BETWEEN
CHARGED GROUP
Most of the Biological product are charged due to intrinsic
chemical group or absorbed ion from the biological
environment.
Interaction of charged group such as amino, carbonyl, sulphate,
phosphate groups facilitate the long range approach of self
assembling sub units.
Charged groups also play role in stabilizing tertiary structure of
folded proteins.
Example of ion pairs -carboxylated /phosphate group boundto
ionized arginine / lysine side chain of protein.
8. 2)HYDROGEN BONDING AND
DEHYDRATION EFFECT
Hydrogen bond are formed between hydrogen atom
attached to an electronegative donor atom (Ex oxygen
,Nitrogen,) and an electronegative or basic acceptor (Ex
carbonyl oxygen).
Hydrogen bond help in base pair matching and
stabilization of Secondary protein structure.
Molecule that form hydrogen bonds are hydrophilicand
these molecules confer significant degree of organization
to the surrounding water molecules.
9. 3)STRUCTURAL STABILITY
The structural stability of Protein in the biological
environment is determined by the interaction between
charged groups and hydrogen bond largely external to
the molecule and vander walls forces largely internal to
the molecule.
Vander walls forces are largely responsible for the
hardness or softness of the molecule. The vanderwalls
interaction among hydrophilic side chains promotes
stability of compact helical structures.
10. METHODS OF PREPARATION
By using the principle of self assembly Aquasomescan
be prepared by three method.
1.Preparation of core.
2. coating of core.
3. Immobilization of drug molecule.
11. 1)PREPARATION OF CORE
This stage mainly depends on the
selection of material for core.
-its physical chemical properties
This can be fabricated by the
-Sonication
-Colloidal precipitation..
For the core material material ceramic material widely
used ,as they are structurally to be known..
12. Commonly used ceramic core are tin oxide, and
calcium phosphate.
Example:
synthesis of nanocrystalline tin oxide core material.
This can be prepared by
-Direct current reactive.
-Magnetron sputtering.
13. 3 inch diameter target of highly purified Tin is
sputtered
↓
High pressure gas mixture of argon and oxygen.
↓
The ultra fine particle form in gas phase are collect on
copper tube and cool at 70oK with liquid nitrogen
14. SYNTHESIS OF NANA CRYSTALBRUSHITE
(CALCIUMPHOSPHATE DIHYRATE)
This can be prepared by
-colloidal dispersion
-Sonication
-By reaction of disodium hydrogen phosphate and
calcium phosphate.
The commonly feature include
-Crystalline
-They measure b/w 50-150nm. And exhibit clean
and reactive surface
15. 2)CARBOHYDRATE COATING
The second step involves coating by carbohydrate on
the surface of ceramic cores.
There are number of processes to enable the
carbohydrate (polyhydroxy oligomers) coating to
adsorb epitaxially on to the surface of the Nano
crystalline ceramic cores.
16. Process generally entail
Addition of poly hydroxy oligomer
↓
To a dispersion of core in ultra pure water.
↓
Lyophilization (to promote the adsorption of
carbohydrate on the surface of ceramic core)
↓
Excess of carbohydrate is removed by
stir cell ultra filteration.
17. Commonly used coating material,
- Cellobiose
- Citrate
- Sucrose
- Trihalose
- Pyridoxal -5- phosphate.
(3) Immobilization of drug
The surface modified Nano crystalline core provide the
solidphase for subsequent non denaturing self assembly for
a broad range of biological active molecule.
Drug can be loaded by partial adsorption
