Nanobiotechnology process of self assembly and self organization organization of bacterial s-layer self organization of virus self organization of phospholipid membrane carbon nanotubes key building block for future nanotechnological application graphene the inorganic nanomaterial quantum dots

1. Process of self assembly and self organization
Based on molecular recognition, relatively simple building blocks
recognize each other, associate with one another and then
associate with other molecules to finally form a well organized
functional entity.
Central to all biological systems as all living cells evolve
from simple building blocks which spontaneously associate
into complex networks and structures.

2. Organization of bacterial S- layers
S-layers are bacterial cell surface structures found in all
archaea and many bacterial species.
Archaea are extremophiles (halophiles and thermophiles),
phylogenetically different from bacteria, having some similarities
to eukaryotes in aspects of transcription and translation.
S-layers have evolved to such stable and well organized
form through evolution of billion of years.

3. S-layers are composed of single protein or glycoprotein
species that assemble into ordered layer which completely
covers the cell surface.
These layers have morphology, symmetry and thickness in
the order of nano range in their natural distribution.
These efficient biological self assembling systems may be
used for making stable nano devices.

5. Self organization of viruses
Another self assembly for nanotechnological applications is
the spontaneous template assisted formation of viral shells.
The most investigated example is that of tobacco mosaic
virus (TMV) which was shown invitro as the first
macromolecular structure of self assembly.
Incubation of viral purified coat proteins and its RNA
spontaneously self assemble and formed virus particles.
These structures are rod like, hollow cylinder with 300nm
length and inner diameter of 4 nm.
Each viral particle contains 2000 protein subunits, arranged
as a right handed helix.

6. The RNA molecule is retained in the helix.
TMV self assembly starts by binding of protein bilayer disk to a
site on the RNA. It results the protein subunits to undergo
through a coordinated rearrangement to yield a helical
nucleoprotein complex.
TMV viral nanoparticles resemble to inorganic or carbon
nanotubes, however they are formed spontaneously by self
assembly at the mild conditions.
TMV nanoparticles have many applications in
metallization.

9. Self organization of Phospholipid memberanes
2-D layers closed in space to form closeed- cage spheroid
structures.
Phospholipid is an amphiphilic molecule having phosphate
head as hydrophilic part and aliphatic tail as hydrophobic
part.
Upon transfer to aqous solution, phospholipid undergoes
through a spontaneous association into bilayer structures.
Aliphatic parts of each layer point towards each other while
the hydrophobic heads point to the bulk water or to inside
part of the closed structure.

11. Phospholipis layers can be manipulated at the nano scale in
the form of tubular structures, hexagonal shapes and
spherical shapes.
Small lipid vesicles known as liposomes are well studied
nanoparticles used for drug delivery.

12. Carbon nanotubes: Key building blocks for future
nanotechnological application
Elongated variants of the C60 fullerenes.
Resembles graphite sheets wrapped around into elongated
cylinders with or without capping at their ends.
Their length to width ratio is extremely high.
Can be formed in a single shell called as single walled
nanotubes (SWNTs)
Or in multiwall fashion known as multiwalled nanotubes
(MWNTs)
They have unique mechanical and electrical properties

13. Have ten time more tensile strength than steel.
Thus are suitable candidate materials for development of
ultra strong materials like in construction of car and
aviation industries.
Can be used as a source of fabrics and clothing for making
lightweight bulletproof fabrics.
Can be used in assembly of an ultra strong cable in
construction of space elevator.
Being very small and highly conductive carbon nanotubes
can be used as molecular wires, conductive composites and
interconnects.

14. Graphene
A single layer of carbon which is one atom thick is called
graphene.
It has high thermal and electrical conductivity and is
mechanically very strong yet strechable material.
Being transparent and very conductive it can be used in
liquid crystal displays and solar cells etc.

15. The inorganic nanomaterials
The noncarbon nanotubes made by inorganic material
which resemble like the carbon fullerene structures.
Tungsten, molebdenum etc can form 2D layer
rearrangements as evidenced in graphite structures for
making nanotube.
The structures that have formed in a cage fashion can be
rolled to form fullerene like structures. For instance the
nano particles of the layered WS2 compound can form
closed cage structures that are similar in their molecular
organization to carbon fullerenes.

16. Used in many industrial and technological applications.
as a solid lubricant
Increases the life span and efficiency of motors and other
power tools with motor parts
Used as additives for motor oil.
Used as lubricants of medical and dental devices.

17. Quantum Dots
The nano objects consist of semiconductor materials
surrounded by a shell composed of ZnS or CdS.
Also called as nanocrystals and have dimensions of few nm
to a few tens of nanometers.
Serve as a cage for electrons and the molecular diameters of
these structures reflect the number of electrons they contain.
The size may depends from a single electron to a collection
of several thousands.

18. Quantum dot behave like a giant atom.
Energy levels in a given quantum dot become quantized due to
confinement of electrons.
The band gap b/w the two energetic states determines the energy
of a photon that is being emitted by the transition b/w the two
states
The energy can be either in the visible or the infrared region
depending on the specific band gap