Chemistry in every day Life

Nanoparticles in Cosmetics and Health

Dr. Christoph Sontag

SC 2201

facebook.com/up.chemistry UP Oct. 2015

•Sun protection by TiO2 and ZnO

Spectrum of visible and uv light UVA and UVB light effects Absorption and Emission

Organic and inorganic sun protection agents

•Color effects of nano sized particles Production of silver and gold nanoparticles Interaction of nanoparticles with light Use of gold particles in artistic works

•Health effects of nanoparticles Antibacterial effect of silver particles

Effects of silver and gold nanoparticles in health science

http://www.slideshare.net/951384/nanotechnology-in-sunscreen-uv-protection

http://www.slideshare.net/951384/nanotechnology-in-sunscreen-uv-protection

http://fashionhoster.com/sun-protection-factor-calculation-selection-tips/#

SPF (sun protection factor) = the factor how much longer someone can stay in the sunshine until reddening of the skin occurs

Higher factors than 30 do not add more protection In addition look for “+” for UV-A protection (also called “sunblock”)

Five things worth knowing about nanoparticles and sunscreens https://www.youtube.com/watch?v=VV0cCg4clMw

Video Clip Demonstration:

Down-side of sun protection: Vit.D deficiency

• Vit.D prevents Osteomalacia in adults (weak bone and muscle) • It maintains a healthy immune system • Sunscreen may create deficiency of vitamin d • Skin needs sun exposure a couple of times per week for good vitamin d levels

http://www.sun-protection-and-you.com/vitamin-d-deficiency.html

Organic and inorganic substances for sunprotection

Sun Protection by organic substances

Absorbs UVA and degrades -> delocalized pi-electrons over 12 atoms In general: alternating single and double bonds (“conjugated bonds”) over a long distance allow electrons to absorb (light)energy easily !

Compare ZnO particles

Mechanical grinded ZnO powder ZnO by chemical reaction

Chemically produced ZnO NP

Zn(CH3COO)2 + 2 NaOH

Zn(OH)(CH3COO) + Na(CH3COO)

Zn(OH)2+ Na(CH3COO)

ZnO

- H2O

Influence of particle size on appearance

http://www.slideshare.net/951384/nanotechnology-in-sunscreen-uv-protection

Physical methods by Nano Particles

TiO2 and ZnO are like semiconductors – UV light can be absorbed

Calculate band gap energy from UV

Absorption of light energy at 400 nm -> E = h ν = h c/λ in eV (Constant h * c = 1.24 eV * μm)

=> E = 1.24 / 0.4 eV = 3.1 eV

“Natural” SPF

How to make all-natural sunscreen https://www.youtube.com/watch?v=zskLjTjktfg

“Whitening”

Hydroquinone is effective, but can lead to formation of benzoquinone, which can cause cancer !! Vitamin C is a better alternative but not as effective. 2% Hydroquinone

Colors of NP

Demo: create Ag NP from AgNO3

Ag+ + NaBH4 + H2O Ag + Na+ + B(OH)3

How to make Au NP

TechNyou Education- Making Gold Nanoparticles https://www.youtube.com/watch?v=JLrn6AsKfuk

surface plasmon resonance (SPR)

http://nanocomposix.com/pages/plasmonics

surface plasmonc resonance where the free conduction electrons in the metal nanoparticle are driven into oscillation due to strong coupling with incident light.

Absorption maximum is size dependent

Nanoparticles in Art works

http://www.smithsonianmag.com/history/this-1600-year-old-goblet-shows-that-the-romans-were-nanotechnology-pioneers-787224/?no-ist

Antibacterial effects Ag and ZnO NP

Test for inhibition of bacterial growth

http://article.sapub.org/10.5923.j.nn.20120206.03.html

Effect on bacterial cell walls

http://www.inbiochem.com/compresa-lazione-battericida-delle-nanoparticelle-dargento/

Drawbacks for the use of Ag NP

Ag NP are toxic for aquatic life, so it is not a very good idea to use it in washing machines or other products that cause water contamination

http://www.wsj.com/articles/SB114955908525572199

Summary • Sun protection by inorganic particles like ZnO is superior over organic chemicals • For sun protection a SPF greater than 30 is not useful • Over-use of sun protection can cause Vit.D deficiency • Skin-whitening can be harmful, esp. using Hydroquinone • Metal NP often form colored suspensions, useful for optical devices, medical applications and art • Especially Ag NP are known for antibacterial activity and are use in wound cremes, textiles, body care products and washing devices – though the released Ag+ ions are toxic to micro organisms

Absorption and Emission