nanoparticles in cosmetics and health
TRANSCRIPT
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://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
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 !
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
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
“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
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.
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