Nanotechnology in sunscreen uv protection, sunscreen, uv protection

1. NANOMATERIALS IN SUN-SCREEN
UV PROTECTION
BY,
A. POOJA SHUKLA
M.Tech (NANO)
1821310006

2. HOW SMALL….???
 Nanoparticles are one-twentieth the thickness of a human hair.
 Nanoparticles are smaller than 100 nanometres and invisible to
the human eye – a nanometre is 0.000001 millimetre.
 Microfine particles are smaller than those used in conventional
white zinc sunscreens, however are larger than nanoparticles –
usually in the range of 100 to 2500 nanometres.

3. PROPERTIES….???
NANOTECHNOLOGY,
 is already making today’s products:
 Lighter
 Stronger
 Faster
 Smaller
 More Durable

4. WHAT ARE SUN RAYS…??
 The sun emits several kinds of electromagnetic radiation: Visible (Vis), Infrared (IR)
and Ultra Violet (UV)
High Energy
Low Energy
 Each kind is distinguished by a characteristic wavelength, frequency and energy
 Higher energy radiation can damage our skin

5. SKIN DAMAGE
 The kind of skin damage is determined by the size of the
energy packet ( E = h x f)
 The UV spectrum is broken into three parts:
 Very High Energy (UVC)
 High Energy (UVB)
 Low Energy (UVA)
• As far as we know, visible and IR radiation don’t harm the
skin

6. SKIN DAMAGE
• Very high energy radiation (UVC)
is currently blocked by the ozone
layer (ozone hole issue)
• High energy radiation (UVB) does
the
most
immediate
damage
(sunburns)
• But lower energy radiation (UVA)
can penetrate deeper into the skin,
leading to long term damage

7. SUN RADIATION SUMMARY
Radiation
Type
Characteristic
Wavelength (l)
UVC
~200-290 nm
(Short-wave UV)
UVB
UVA
~290-320 nm
(Mid-range UV)
~320-400 nm
(Long-wave UV)
Vis
~400-700 nm
IR
~700-120,000 nm
Increasing
Wavelength
Energy per
Photon
Increasing
Energy
High Energy
Medium Energy
% of
Total Radiation
Reaching Earth
Effects on
Human Skin
Visible
to
Human
Eye?
~0%
DNA Damage
No
Sunburn
DNA Damage
Skin Cancer
No
Tanning
Skin Aging
DNA Damage
Skin Cancer
No
~43 %
None
Currently
Known
Yes
~49%
Heat Sensation
(high l IR)
No
(<1% of all UV)
~.35%
(5% of all UV)
~6.5%
Low Energy
Lower Energy
Lowest Energy
(95 % of all UV)

8. NANOPARTICALS IN SUN-SCREEN
 The nanoparticles used in sunscreens
and other consumer products may have
novel biological and physical properties,
which can lead to unusual effects – both
good and bad.
 Nanoparticles found in sunscreens are
either titanium dioxide or zinc oxide.

9. WHY USE SUN-SCREEN….??
Too much unprotected sun exposure leads to:

Premature skin aging (e.g. wrinkles)

Sunburns

Skin cancer

10. WHY NANOMATERIALS IN SUN-
SCREEN…??
Sunscreens made with zinc oxide and titanium dioxide
generally score well because:
 they provide strong sun protection with few health concerns
 they don’t break down in the sun
 zinc oxide offers good protection from UVA rays – titanium
oxide less so, but better than most other active ingredients.

11. Inorganic UV Filters
NANOMATERIALS….??
 Titanium
dioxide (TiO2) and zinc oxide (ZnO) pigments are
commonly used in personal care products to provide protection
against UVA and UVB
 They attenuate UV light by absorption and scattering
 They are usually surface coated to minimize photo-catalytic activity.
 They
are typically produced as finer crystals from the same feed
stocks and with similar processes as pigmentary grades.

12. MANUFACTURING
PROCESS

13. Manufacturing is a two step process :
Process
 The production of TiO and ZnO
2
1. Purification of the raw material
2. Growing of crystals (primary particles) of the desired size
 They are two different processes for TiO2, known as sulfate and chloride,
and three for ZnO, known as American, French and Wet.
 Crystals are grown at high temperatures to the required sizes : 200 nm and
above (pigmentary grades) and finer than 200 nm (attenuation grades).
Attenuation grades
10nm
Pigmentary grades
200nm

14. Surface Treatment of Inorganic UV Filters
Pigment type
(primary particle size)
Surface
Treatment
Pigmentary TiO2
(410 nm)
Attenuation grade TiO2
(30 - 50 nm)
Attenuation grade ZnO
(15 - 35 nm)
Treatment
Rate *
None
4.76
2% Methicone
< 0.01
Alumina
0.13
3% Lecithin
0.033
None
1.83
3% Methicone
< 0.01
M. Kobayashi and al., Cosm & Toil., Vol. 112, No. 6, p83, 1997
* Rate constant of the first order reaction of oxydation of acetalydehyde
It is common industry practice to use surface treated inorganic UV filters when
formulating sunscreens.

15.  Attenuation of UV light is influenced by particle size.
 Scattering of visible light (whitening effect) is influenced by particle
size and the difference between the refractive index of the pigment
and the surrounding media.
 Maximum scattering occurs when size equals 1/2 the wavelength and
particles are uniformly dispersed (Mie theory).
Wavelength
Particle size

16. TiO2
15nm

17. TiO2 Dispersions in Cyclopentasiloxane
195
60
35
15
10 nm
195
195
60
35
15
10 nm
195
60
60
35
15
10 nm
35
15
10 nm
10nm TiO2 (110 nm dispersion particle size) makes transparent dispersions for all skin
types.
All dispersions diluted in Cyclopentasiloxane (to 20% TiO2)

18. Particle Size and UV attenuation
UVB / UVA
100 - 120 nm
balance
7.0 - 8.0
120 - 150 nm
3.4 - 5.5
11 - 55
20 nm
130 - 160 nm
2.0
9
35 nm
150 - 180 nm
1.5 - 2.0
7 - 17
150 nm
> 250 nm
1.1
2.6
20 nm
130 - 180 nm
1.0 - 1.1
30 - 37
60-100 nm
180 - 250 nm
1.1
6.3
120 nm
ZnO
Dispersion
particle size
15 nm
TiO2
Primary particle
size
10 nm
Pigment
> 250 nm
0.9
2.9
(1)
Transparency
308/360 extinction ratio : indication of UVB/UVA balance
(2) 308/524 extinction ratio : indication of transparency
(1)
70 - 90
(2)

19. Conclusions
 Attenuation grade Titanium Dioxide and Zinc Oxide are produced
using the same processes as larger pigmentary grades. They are
usually surface coated to minimize their photo-catalytic activity.
 TiO2 and ZnO attenuate UV light according to their particle size :
 Small primary particle sizes (10 - 15 nm) are necessary to produce
dispersions (100 - 150 nm) transparent to visible light and efficient
against UVB.
 ZnO and larger TiO2 (35 - 150 nm) are more efficient against
UVA.
 The particle size of pigmentary grades are appropriate to scatter
visible light, but they are not efficient at attenuating UV light or
effective as sunscreens.

20. With all of this possible damage, it pays
to wear sunscreen, but which one should
you use?
PRODUCTS….???

23. FREQUENTLY ASKED

24. Do the shape and size of the particles affect sun protection?
Yes. The smaller they are, the better the SPF protection and the worse the UVA
protection. Manufacturers must strike a balance: small particles provide greater
transparency but larger particles offer greater UVA protection. The form of zinc
oxide most often used in sunscreens is larger and provides greater UVA protection
than the titanium dioxide products that apply clear on the skin.
Do the nanoparticles in sunscreen penetrate the skin?
No. Some studies indicate that nanoparticles can harm living cells and organs, but
there is no evidence that zinc oxide and titanium dioxide nanoparticles penetrate
skin in any significant quantities.
Could nanoparticles that penetrate the skin cause skin damage when
energized by sunlight?
Possibly but unlikely, since the materials don’t penetrate deep enough in skin to
reach living skin cells.

25. APPLICATION
 Blocks UVA and UVB radiation
 Full SPF protection
 Protects from SKIN RASHES
 Avoids SKIN CANCER
 Avoids SKIN AGING
Twenty different skin cancer lesions

26. REFERENCES
1.
Images : source internet
2.
http://en.wikipedia.org/wiki/Sunscreen
3.
Nano-ingredients in sunscreen, The need for regulation, july 2012
4.
Nanotechnology and cosmetics, November 2008
5.
http://www.ewg.org/2013sunscreen/nanoparticles-in-sunscreen/
6.
http://spie.org/x33993.xml
7.
http://www.uvawareness.com/sunscreen-info/sunscreen-information.php
8.
http://www.cancer.org.au/preventing-cancer/sun-protection/nanoparticlesand-sunscreen.html
9.
http://www.csiro.au/en/Portals/Publications/Brochures--FactSheets/sunscreens-FAQ.aspx

27. THANK YOU……..!!!