By-

Vaibhav Kumar Maurya

Ph.D Scholar

NIFTEM,

Haryana, India

Richard Feynman (1959) laid foundation

step of nanotechnology in his lecture on

“there is plenty of room at the bottom”.

Term was given by Nario Taniguchi and

popularized by Drexler

Nano means dwarf (Greek word “nanos”).

Defination: The manipulation of matter

with at –least one dimension sized

between 1 to 100 nanometers (by National

Nanotechnology Initiative)

A Nanometre is a unit of length in the

metric system, equal to one billionth of a

metre (10-9).

Technology is the making, usage, and knowledge of tools, machines and

techniques, in order to solve a problem or perform a specific function.

Nanoparticle characterization is necessary to establish understanding

and control of nanoparticle synthesis and applications.

Characterization is done by using a variety of different techniques like:

Scanning Tunneling microscope (STM) are scanning probes

Atomic force microscopy (AFM)

Electron microscopy (TEM, SEM)

Dynamic light scattering (DLS)

X-ray photoelectron spectroscopy (XPS)

Powder X-ray diffraction (XRD)

Fourier transform infrared spectroscopy (FTIR)

Matrix-assisted laser description/ionization time-of-flight mass

spectrometry (MALDI-TOF)

Ultraviolet-visible spectroscopy

Dual polarisation interferometry and

Nuclear magnetic resonance (NMR)

Synthesis of Nanomaterials

Two approaches:

1. Bottom-up

2. Top-down

Bottom-up Approach

In the bottom-up approach, molecular components arrange themselves

into more complex assemblies atom-by-atom, molecule-by-molecule,

cluster-by cluster from the bottom (e.g., growth of a crystal).

Molecular components arrange themselves into some useful

conformation using the concept of molecular self-assembly.

For example, synthesis of nanoparticles by colloid dispersions.

Top-down Approach

In this approach,

nanoscale devices

are created by

using larger,

externally-

controlled devices

to direct their

assembly.

The top-down approach often uses the traditional workshop or micro-

fabrication methods in which externally-controlled tools are used to cut,

mill and shape materials into the desired shape and order.

Attrition and milling for making nanoparticles are typical top-down

processes.

Hybrid Approach

Both the techniques i.e., bottom-up and top-down are employed.

Lithography is an example in which the growth of thin film is a bottom-

up method whereas itching is a top-down method.

Nanoparticles are synthesize using techniques such as ultraviolet

irradiation, aerosol technologies, lithography, laser ablation, ultrasonic

fields and photochemical reduction techniques.

Disadvantages: Expensive and involve use of hazardous chemicals.

Green synthesis: make use of biological systems (microbial sysnthesis)

Disadvantages: low monodispersity, low production rates and high

production costs.

Structure of Nanomaterials

Classified by their dimensions:

Zero-dimensional nanostructures – nanoparticles

One-dimensional nanostructures – whiskers, fibers (or fibrils),

nanowires, nanorods, nanocables and nanotubes

Two-dimensional nanostructures – thin films

Three-dimensional nanostructures – colloids bearing complex shapes

Carbon Nanotubes (CNT)

Tubular form of carbon

- Diameter - as small as 1nm

- Length – few nm to microns

Configuration is similar to 2D graphene

sheets rolled in a tube.

Two types of carbon nanotubes:

1. Single wall Nanotubes (SWNT): made up of single rolled graphene layer,

difficult to synthesize in pure, defect-free form. It accumulates less in the

body, hence used for biomedical purposes.

2. Multi wall Nanotubes (MWNT): made of bunch of graphene layers rolled

together. Bulk synthesis is easy, high purity is attained. It accumulates

more in the body.

Applications:

Helps in creating light weight spacecrafts.

Easily penetrate membranes such as cell walls – helps in cancer detection

and treatment.

Helps in developing sensors that can detect chemical vapours.

Fabrication of gene chip can be done – used for environmental monitoring

and pathogen detection.

Limitations:

Difficult to produce in bulk, maintaining homogeneity and purity.

It’s scarcely soluble in water – can be overcome by fictionalization.

Quantum Dots (Nanorods)

A crystalline nanoparticle made of semiconductor material, small

enough to show quantum mechanical properties.

Dimensions range from 1-100 nm.

Electronic properties are intermediary of bulk semiconductor and

discrete molecules.

They are closely related to their shape and size, the size is inversely

proportional to band gap.

Made from range of materials – zinc sulphide, lead sulphide, cadmium

selenide, and indium phosphide.

Can be toxic while using in human body therefore coated with a

protective polymer.

Application:

Detection of toxins and pathogens, and defining their characteristics

including virulence. Examples of pathogens targeted so far:

Cryptosporidium parvum, Giardia lamblia, Escherichia coli

0157:H7, Salmonella Typhi and Listeria monocytogenes.

Used in display technologies.

Used in micro-electromechanical systems (MEMS).

Used in cancer therapeutics.

Nanowires (Quantum Wires)

Extremely thin wire

- Thickness or diameter = ≤ 10-9m.

- Aspect ratio (length-to-width ratio) = ≥ 1000

Applications:

Development of microprocessors, prototype sensors and nanobots.

Used for bio-sensing purposes.

Nanowire based devices are ultrasensitive and thus can detect wide

range of biological and chemical species from DNA to drug molecules

and viruses and pH.

Can detect the presence of altered genes associated with cancer and

even determine the exact location of the mutation.

Nanofiber

Produced from a variety of polymers like nylon, polystyrene,

polyacrylonitrile, polycarbonate and water soluble polymers.

Generally not used as a single fiber thus, layered as a sheet or mat.

Properties: Low density, large surface area to mass, high pore volume,

small pore size, superior mechanical properties and possibility to

incorporate different additives.

Applications:

Peptide nanofibers associates to form nanofiber scaffold with well-

ordered nanopores - ideal material for 3D cell culture of artificial

organs, or tissues, controlled cell differentiation, regenerative medicine,

wound healing and slow drug delivery applications.

Used to make sensors to detect chemical agents; filters for air, water,

beverage, oil and fuel purification; lightweight clothing; better

efficiency batteries and food packaging.

Nanobiosystems, Medical, and Health Applications

Enhanced biological imaging for medical diagnostics (Quantum

dots).

Early diagnosis of atherosclerosis or the build up of plaque in

arteries.

Detection of early-stageAlzheimer’s disease (Gold particles).

Detect rare molecular signals associated with malignancy.

Multifunctional therapeutics.

Agriculture Applications

Nanotechnology enables delivery of agriculture chemicals

(fertilizers, pesticides, herbicides, plant growth regulators etc).

Field sensing system to monitor the environmental stresses and crop

condition.

Nanotechnology enables the study of plant disease mechanisms.

Improving plant traits against environmental stresses and diseases.

Electronics and Information technology Applications

Nanoscale transistors.

Magnetic random access memory (MRAM) enabled by

nanometer‐scale magnetic tunnel junctions.

Displays for electronic items incorporate

nanostructured polymer films known as

organic light-emitting diodes (OLEDs).

Flash memory chips for iPod nanos.

Ultraresponsive hearing aids.

Morph, a nanotechnology concept

device developed by Nokia Research

Center (NKC) and the University of

Cambridge (UK).

Antimicrobial/antibacterial coatings on mouse/keyboard/cell phone

casings.

Conductive inks for printed electronics for RFID/smart cards/smart

packaging.

More life-like video games.

Flexible displays for e-book readers.

Sustainable Energy Applications

Prototype solar panels.

Improved efficiency of fuel production and consumption.

Nano-bioengineering of enzymes.

Batteries.

Conversion of waste heat in computers, automobiles, homes,

power plants, etc., to usable electrical power.

An epoxy containing carbon nanotubes - used to make windmill

blades.

Nanostructured materials - to improve hydrogen membrane and

storage materials and the catalysts needed to realize fuel cells for

alternative transportation technologies at reduced cost.

Low-friction nano-engineered lubricants for all kinds of higher-

efficiency machine gears, pumps, and fans.

More efficient lighting systems in advanced electronics.

Light-responsive smart coatings for glass to complement alternative

heating/cooling schemes.

High-light-intensity, fast-recharging lanterns for emergency crews.

Environmental Remediation Applications

Lighter cars and machinery requiring less fuel or alternative fuel and

energy sources.

Affordable, clean drinking water.

Nanofabric "paper towel”.

Many airplane cabin and other types of air filters are nanotechnology-

based filters that allow “mechanical filtration”.

New nanotechnology-enabled sensors - to detect, identify, and filter out,

and/or neutralize harmful chemical or biological agents in the air and

soil with much higher sensitivity than is possible today.

Other uses

800 commercial products rely on nanoscale materials and processes (NNI).

Nanoscale additives used in polymer composite materials for baseball bats,

tennis rackets, motorcycle helmets, automobile bumpers, luggage, and

power tool housings.

Fabrics - resist wrinkling, staining, and bacterial growth, and provide

lightweight ballistic energy deflection in personal body armor.

Nanoscale thin films on eyeglasses, computer and camera displays,

windows, and other surfaces.

Cosmetic products.

Nano-engineered materials in the food industry include nanoencapsulation,

nanocomposites in food containers.

Nanosensors built into plastic packaging - warns against spoiled food.

Nanosensors - to detect salmonella, pesticides, and other contaminates

on food before packaging and distribution.

Nano-engineered materials in automotive products:

– high-power rechargeable battery systems;

– thermoelectric materials for temperature control;

– lower-rolling-resistance tires;

– high-efficiency/low-cost sensors and electronics;

– thin-film smart solar panels; and

– fuel additives and improved catalytic converters for cleaner exhaust and

extended range.

Nano-engineered materials make superior household products.

Nanostructured ceramic coatings.

Nanoparticles are used in catalysis to boost chemical reactions. -

petroleum refining and in automotive catalytic converters.

Silver nanocrystals embedded in bandages to kill bacteria and prevent

infection.

Nanoparticulate-based synthetic bone: formed by manipulating calcium

and phosphate at the molecular level.

Aerogels lightest known solid due to good insulating properties is used

in space units and are proposed to use in space craft.

Nanotechnology in INDIA

IIT Mumbai is the premier organization in the field of nanotehcnology.

Institute of Nano-science and Technology (INST), Mohali.

Research in the field of health, environment, medicines are still on.

Starting in 2001 the Government of India launched the Nano Science and

Technology Initiative (NSTI).

In 2007 the Nanoscience and Technology Mission 2007 was initiated for a period

of five years.

The main objectives of the Nano Mission are:

Basic research promotion.

Infrastructure development for carrying out front-ranking research.

Development of nano technologies and their applications.

Human resource development and

International collaborations.

Future

Researchers are developing wires containing carbon nanotubes to have

much lower resistance than the high-tension wires currently used in the

electric grid and thus reduce transmission power loss.

To power mobile electronic devices, researchers are developing thin-film

solar electric panels that can be fitted onto computer cases and flexible

piezoelectric nanowires woven into clothing to generate usable energy

on-the-go from light, friction, and/or body heat.

Researchers are investigating carbon nanotube “scrubbers,” and

membranes to separate carbon dioxide from power plant exhaust.

Researchers are investigating particles such as self-assembled

monolayers on mesoporous supports (SAMMS™), dendrimers, carbon

nanotubes, and metallo-porphyrinogens.

Nanoparticles will in future be used to clean industrial water pollutants

in ground water.

The future of nanotechnology could include the use of nanorobotics.

These nanorobots have the potential to take on human tasks as well as

tasks that humans could never complete. The rebuilding of the depleted

ozone layer could potentially be able to be performed.

There would be an entire nano surgical field to help cure everything

from natural aging to diabetes to bone spurs.

There would be almost nothing that couldn’t be repaired (eventually)

with the introduction of nano surgery.

Pitfalls of Nanotechnology

Nano-particles can get into the body through the skin, lungs, and digestive

system, thus creating free radicals that can cause cell damage.

Once nano-particles are in the bloodstream, they will be able to cross the

blood-brain barrier.

Nanobots because of their replicating behavior can

be big threat to GRAY GOO.

The most dangerous Nano-application use for

millitary purposes is the Nano-bomb that contain

engineered self multiplying deadly viruses that can

continue to wipe out a community, country or even a

civilization.

“The Next Big Thing Is Really Small”

Questions..??

Is Nanotechnology boon or bane for the society. Comment.

What could be the future applications or outcomes of

Nanotechnology?

References:

www.nptel.ac.in

www.nano.gov/you/nanotechnology-benefits

www.slideshare.net/kirtisingh2011/nanotechnology-ppt

Chen, H., and Yada, R. (2011). Nanotechnologies in agriculture:

New tools for sustainable development. Trends in Food Science

and Technology. 22, 585-594.