Silver Nanoparticles
(nanosilver)
By
Chris Coulter
Main use
• Antibacterial :
– Anything that destroys bacteria or suppresses
their growth or their ability to reproduce.
• Antifungal:
– Anything that destroys fungi or suppresses their
growth or their ability to reproduce.
Silver uses through history.
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The Greeks used silver vessels to keep
water and other liquids fresh.
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Pioneers in American found that if they
placed silver or copper coins in their casks
of drinking water, it kept the water safe
from bacteria, algae, etc.
•
In the Middle Ages, the wealthy stored
and ate their food from silver vessels to
keep bacteria from growing. This
protected them from the full brunt of the
plague.
•
Silver leaf was used to combat infection in
wounds sustained by troops during World
War I.
•
Settlers in the Australian outback
suspend silverware in their water tanks to
retard spoilage.
•
In the early 1800s, doctors used silver
sutures in surgical wounds with very
successful results.
•
Similarly silver dollars were put in milk to
keep it fresh.
•
Prior to the introduction of antibiotics,
Colloidal Silver was used widely in
hospitals and has been known as a
antibacterial for at least 1200 years.
Applications
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Cosmetics
Odor control
Antimicrobial coatings
Burn and Wound dressing
Appliances
Filters
Soap
• Silver particles penetrate
into cells and prevent the
breathing of virus, bacteria,
mold, and fungus, ultimately
killing them.
• Antibiotics are effective
against 12 kinds of bacteria
at most.
• Silver can kill about 650
kinds of germs including
viruses that are unaffected
by antibiotics.
Odor Control
- kills bacteria that cause odor –
Effective against athletes foot?
Deodorant
Socks and insoles
Antimicrobial coatings
- Effective against resistant strains of bacteria •
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Keyboards
Phones
Appliances
Handrails
Doorknobs
Toilet seats
– In Hong Kong a Nano SilverTitanium Dioxide coating
(NSTDC) has been certified as
effective in killing a wide range
of bacteria, viruses and mold
including the H1N1 flu virus.
This coating will be applied to
all surfaces touched in the
Hong Kong metro rail system.
• Paint
– A research group at the City
College of NY working with Rice
University in Houston
developed an antibacterial
paint.
– They tested it by leaving E.Coli
overnight on a plain glass slide,
one coated with regular paint,
and one coated with nanosilver
paint.
• The nanosilver paint coated slide
killed all of the bacteria.
– This can be used in hospitals to
cover counters and walls where
there is a high risk of spreading
germs.
– Also very useful in homes.
• Especially in bathrooms to keep
germs and mold from breeding.
Burn and Wound Dressing
• Burns are very susceptable
to bacterial infections.
• Current silver burn gel
contains enough silver to
cause toxic effects.
– Nano based silver burn gel
contains 30 times less silver.
Doesn’t cause the side
effects (skin discoloration
and cell damage) while still
being effective against drug
resistant microbes.
• Blood Clotters.
Appliances
Samsung Silver Nano Washing Machine and Refrigerator.
Silver ions released during wash and
rinse cycles
Clothes become antibacterial: killing odor
caused by sweat or fungus for up to 30 days
Samsung Silver Nano refrigerator
A Silver Nano coating to the inner surfaces of refrigerator cause
an anti-bacterial and anti-fungal effect.
As air circulates, the coated
surfaces allow the silver ions to kill
the airborne bacteria.
Filters
• Cotton cloth dipped in a
solution of silver nanowires
and carbon nanotubes.
• An electrical current
supplied by a small solar
panel kills 98% of bacteria
in a single pass.
• Filters about 80,000 times
faster than filters that trap
bacteria.
• Also used in air filters to
improve effectiveness.
Problems and fears
• Silver itself is classified as an environmental hazard by
EPA because it is more toxic to aquatic plants and
animals than any metal except mercury.
– Nanosilver particles are small enough to cross through egg
membranes and into fish embryos.
• Wastewater
– Silver nanoparticles destroy the benign species of bacteria
that are used for wastewater treatment.
– Silver nanoparticles may become concentrated over time.
– Tests are being conducted to see long term effects.
Other uses
• Nano silver paste and ink
– Printed Circuit Boards (PCB).
• Low cost
• Bendable
• Paper Batteries
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Small
Durable
Long lasting
Can be crumpled or folded with no loss of
performance
Paper Batteries
• One dimensional structure
helps ink stick strongly.
• Paper super-capacitors may
last through 40,000 chargedischarge cycles.
– At least 10 times more than
lithium batteries.
• The high surface to volume
ratio of paper gives it an
advantage in uses like hybrid
and electric cars because of
it’s quick transfer of
electricity.
•
Can be made into a paint to
make walls into a battery.
Any Questions?