Transcript Life Sciences - Human Resource Development Centre

N. Ponpandian – BU-NST
Bharathiar University
Coimbatore
Nanostructures and its Applications
N. Ponpandian
Department of Nanoscience and Technology
Bharathiar University
Coimbatore 641 046
Email: [email protected]
Web: http://www.bunst.org
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ELECTRON WAVES Separate
NanoSCIENCE from MicroSCIENCE
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The discovery that electrons = waves led to QUANTUM MECHANICS
A weird, new, counter intuitive, non-Newtonian way of looking at the nano world
With a particular impact upon our understanding of electrons: Electrons => Waves
How do you figure out an electron’s wavelength?
electron = h / p “De Broglie’s Relationship”
( = electron wavelength, h = Planck’s Constant, p = electron’s momentum)
This relationship was based on series of experiments late 1800’s / early 1900’s
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To put the size of an electron’s wavelength in perspective:
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How to see the Nanoparticles?
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Size of Things
(red = man-made things)
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Millimeters
Ball of a ball point pen
Thickness of paper
Human hair
Talcum Powder
Fiberglass fibers
Carbon fiber
Human red blood cell
E-coli bacterium
Size of a modern transistor
Size of Smallpox virus
0.5
0.1
0.02 - 0.2
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Microns
Nanometers
100
20 – 200
40
10
5
4–6
1
0.25
0.2 – 0.3
250
200 – 300
___________________________________________________________________________________________________
Electron wavelength: ~10 nm or less
Diameter of Carbon Nanotube
Diameter of DNA spiral
Diameter of C60 Buckyball
Diameter of Benzene ring
Size of one Atom
3
2
0.7
0.28
~0.1
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2a
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a
a
a
A = 4 x 2 a x a + 2 a2 = 8 a2 + 2 a2 = 10 a2
A = 6 x a x a + 6 a x a = 12 a2
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Types of materials
1. Metals – No band gap
2. Semiconductors – low band gap
3. Insulators – very high band gap
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• Quantum dots are nanocrystals of semiconductors that
exhibit quantum confinement effects, once their
dimensions get smaller than a characteristic length, called
the Bohr’s radius.
• This Bohr’s radius is a specific property of an individual
semiconductor
• Bohr’s radius can be equated with the electron–hole
distance in an exciton that might be formed in the bulk
semiconductor.
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• Below this length scale (Bohr’s radius) the band gap (the gap
between the electron occupied energy level, similar to
HOMO, and the empty level, similar to LUMO), which are is
size-dependent.
• Band gap is Size Dependent
Conduction band
Valence band
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Structural differences
Nanoscale Carbon
Bulk Carbon
C60 (Buckeyball)
Smalley, Curl, Kroto
1996 Nobel Prize
Graphite
Diamond
Carbon Nanotubes
Sumio Iijima - 1991
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Fe filled MWCNT: Bio-compatible nanomagnets
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Fe filled MWCNT: Bio-compatible nanomagnets
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Why nanocrystalline materials t of have excellent soft magnetic properties
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Lex
?
D
AK1
H c  pc
Js D
Random Anisotropy Model
2
AK
Grain size > exchange length
41 6
J
D
AK
K
D
s
1
H
1
H pp
Hcc ppc c J D
soft magnetic properties  as grain size 
c
c
i
3
AK
s
Js A
0J s D 1
J s2 4D 6
J s2 A3 Grain size < exchange length
  p K1 D
Hi  pc AK3   p
as grain size
4 6 soft magnetic properties 
0
c
Js A 1 i
 0 K1 D 
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
Response of superparamagnets
to applied field described by
Langevin model

Qualitatively
paramagnets

At
room
temperature
superparamagnetic
materials
have a much greater magnetic
susceptibility per atom than
paramagnetic materials
similar
to
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• Iron and living things
 Many animals use magnetic fields to navigate
 Synthesize hemoglobin
 Role of iron in neurodegenerative disease
• Medical applications
 Removal of iron splinters, shrapnel, etc.
 Holding prosthetics
 Guiding instruments through the body
 MRI
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• Magnetic imaging
• Magnetic heating (Hyperthermia)
• Targeted drug delivery
• Detection/purification/isolation
• Manipulation
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Goal: Separate/detect/isolate one type of cell
from others, often when the target is present in
very small quantities
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Functionalized nanoparticles
O
R
O-
O-
O
Ligand
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Cells
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Magnetic nanoparticles bond with targeted cells
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Retain desired cells by applying a magnetic field
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• Cancer cell growth is slowed or stopped at 42 °C - 46 °C
• Magnetic materials inside the body generate heat due to
• Hysteresis
• Brownian motion
• Eddy currents
• Nanoparticles provide
• uniform heating
• non-invasive delivery
• multiple treatments
• Human clinical trials in progress (Germany)
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Magnetic resonance imaging
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Non-invasive method used to render images of the
inside of an object
Primarily used in medical imaging to demonstrate
pathological or other physiological alterations of living
tissues
MRI is currently the most efficient imaging procedure
used in medicine
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Typical MRI device
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Typical MRI images
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Problems in MRI
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Low contrast between different tissues
Low contrast between a healthy tissue and tumors
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Contrast agents
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Different contrast agents are administered in 40–50%
of all MR examinations in order to improve the
efficiency of this procedure
Contrast agents are diagnostic pharmaceutical
compounds
containing
paramagnetic
or
superparamagnetic metal ions or nanoparticles that
affect the MR-signal properties of surrounding
tissues
Gadolinium chelates are the most widely used
extracellular, non-specific contrast agents
Organ
specific
contrast
agents
include
superparamagnetic iron oxides nanoparticles
stabilized with appropriate biopolymers or
biocompatible synthetic polymers
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Clinically approved superparamagnetic contrast
agents stabilized with biopolymers
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Ferumoxide (Endorem, Feridex)  dextran stabilized
Ferumoxtran (Sinerem, Combidex)  dextran
stabilized
Ferucarbotranum (Resovist)  carboxydextran
stabilized
Used for intravenous applications
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MRI of liver tumor
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After SPIO application
Normal liver tissue
contains phagocytic
Kupffer cells 
darkening
after
dextran-coated
SPIO application
Cancer cells do not
contain Kupffer cells
 after dextrancoated
SPIO
application tumor is
brighter
that
surrounding tissue
Before SPIO application
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MRI of gastrointestinal tract
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Oral application of superparamagnetic nanoparticles
Small bowel before (left) and after (right) application of the oral50 of xx
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MRI of gastrointestinal tract
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Commercially available contrast agents:
Ferumoxsil (GastroMARK, Lumirem)  silicon-coated
superparamagnetic iron oxide
Ferristene (Abdoscan)  sulphonated styrenedivinylbenzene latex particles (Ø 3.5 μm) with bound
superparamagnetic nanoparticles
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 Nanomedicine is an interdisciplinary field of science, even a simple
project needs contributions from physicists, engineers, material
chemists, biologists and end users, such as an orthopaedic surgeon.
 A mature nanomedicine will require the ability to build structures and
devices to atomic precision, hence molecular nanotechnology and
molecular manufacturing are key enabling technologies for
nanomedicine.
 Medicine must catch up with the technology level of the human body
before it can become really effective. The result will be the ability to
analyse and repair the human body as completely as we can repair a
conventional machine today.
 If the nanoconcept holds together, it could be the groundwork for a
new industrial revolution.
 BUT: can all different scientists and engineers work together to achieve
crossover dreams?
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 Despite the importance of nanotechnology, literature review of
robotics in 1993 included not a single reference to
nanotechnology or nanomedicine.
 The first nanomedical device design technical paper in 1998 by
Freitas: Respirocyte – an Artificial Red Cell.
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 Nature has created nanostuctures for billenia.
Biological systems are an existing proof of molecular
nanotechnology.
 Biology is an ingenious form of nanotechnology, even
very simple living cells are able to duplicate. So far
there is no machine of any size or type, which could
do the same.
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 Replication is a basic capability for molecular
manufacturing. Still some scientists think that
medical nanorobots need not ever replicate.
 It is unlikely that the FDA would ever approve a
use of a medical nanodevice that was capable of
in vivo replication. Replicators will be very tightly
regulated by governments everywhere. In practice
you would not want anything that could replicate
itself to be turned loose inside your body.
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 Nanomedicine will eliminate
virtually all common diseases, all
medical pain and suffering =>
theoretically eternal life.
 Extension of human capabilities.
Pollution-free industry will
guarantee the well-being for
the nature.
 New era of peace. People who
are well-fed, well-clothed, welleducated, healthy and happy will
have little motivation to make
war.
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 Self replicating nanorobots
could become massive chemical
and biological weapons.
 Changes to human properties,
such as brains, respiration,
muscles and DNA will be
uncontrolled and may threat
the existence of human being.
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 Nanoparticles can deliver drugs in a sophisticated
ways, like target specific and trigger based drug
dose.
 Target specific delivery enables the use of
lower doses, because the whole body is not
saturated with the drug.
 The side effects will be minimized, and it is
possible to use stronger drugs, which could
not be used by conventional drug delivery.
 The use of gold particles in cancer healing is an
example target specific action.
 Gold plated spheres are linked to tumor cells.
Nanoshells can be heated from the outside
using an infrared source. Heating the shells
destroy the cancerous cells, leaving the
surrounding tissue unharmed.
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 Using magnetic nano particle can Improve imaging with better
contrast agents and helps to diagnose diseases more sensitively.
 The method enables the detection of very small tumors and
other organisms which cause disease. When the diagnostics is
improved the healing will also be easier.
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 Semiconductor
nanocrystals,
quantum dots, absorb only photons
of light omitting just the right
wavelength for their size.
 Use of a variety of sizes and
concentrations of quantum dots
produces a spectral bar code with
distinct spectral lines. Such method
allows multiple labels.
 Fast and accurate DNA testing,
comparison of genetic material,
rewriting DNA sequences in vivo,
and even home DNA test systems.
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 SurroMed company is developing
nanobarcode®
technique
with
researchers from the Penn State
University.
 The idea is to use little metallic bars.
Consecutively alternating gold- and
silver-bands on a bar are interpreted
as individual bits.
 Twenty bands equal twenty bits ≈ 106
alternatives.
 The bands can be interpreted with an
optical microscope.
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 Numerous DNA-testers can be attached to a single bar, the testers
combine with receptor molecules. The complex formation results
a multiple DNA-sequence analysis. Also antibody molecules can
be attached to a surface of a bar, after an immunologic reaction
peptide hormones can be analysed.
 Hundreds of components can be measured from one milliliter of
serum, multiple test tubes and plentiful blood samples become
unnecessary.
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 The connection between
implant material and bone/
surrounding tissues is a key
factor to a successful and
long-term
use
of
prostheses.
 Nano-scale modifications
of implant surfaces would
improve implant durability
and biocompatibility.
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Teeth cleaning robots collect harmful bacteria from the mouth.
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 Similar cleaning robots can be used in lungs. We have natural
macrophages in alveoli, but they are not able to metabolize
foreign particles like fibers of asbestos and toxic effects of
smoking from the lungs.
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Extra fat can be removed from the arteries with cleaning robots.
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 It is an artificial mechanical red blood cell floating along in the bloodstream. A
spherical (d = 1 μm) nanomedical device is made of 18*109 atoms (mostly
carbon).
 The design of respirocyte was the first technical paper on nanomedical device
design. It was published in 1998 by Robert A. Freitas.
 It is important to notice that molecular nanotechnology violates no physical
laws and there are technical paths leading to useful results.
 Respirocyte device cannot be built today
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 A nanostructured data storage device measuring a volume
about the size of a single human liver cell can store an
amount of information equivalent to the entire library.
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 Researchers hope to figure out ways to regenerate skin,
bone and more sophisticated organs.
 At present auto-, allo- and xenografts plus some artificial
materials are being used for reconstruction of damaged
tissues and organs.
 The amount of auto- and allografts is limited, and allo- and
xenografts carry a risk of infection (HIV or BSE).
 So the need and interest for artificial regeneration definitely
exists!
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




Shape and size
Biocompatibility
Powering
Communication
Navigation
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Albert Fert
Université Paris-Sud
Unité Mixte de Physique
CNRS/THALES
Orsay, France
Peter Grünberg
Forschungszentrum Jülich
Jülich, Germany
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FM
2
FM
1
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