The Environmental and Biological Implications of Nanoparticles - - PowerPoint PPT Presentation

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Jul 13, 2023 145 likes •325 views

The Environmental and Biological Implications of Nanoparticles Faculty Advisor: Dr. Arturo Keller UC Center for the Environmental Implications of Nanotechnology INSET Project Mentor: Dr. Milka Montes Jason Gehrke, Chemistry Major, Santa Barbara

SLIDE 1

The Environmental and Biological Implications

f Nanoparticles

Faculty Advisor: Dr. Arturo Keller UC Center for the Environmental Implications of Nanotechnology INSET Project Mentor: Dr. Milka Montes Jason Gehrke, Chemistry Major, Santa Barbara City College

SLIDE 2

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Nanoparticle Lifecycles

 Expand on the knowledge of nanoparticles (NPs)  Increase understanding of NP life cycle  During use and after entering environment  Interactions with biological systems

http://www.futurity.org/science-technology/designer-dots-could shield-food-chain/

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Silver Nanoparticle Size

http://www.jnanobiotechnology.com/content/figures/1477-3155-3-6-1.jpg

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Amino Acid Adsorption and NP Behavior

 TiO2 and Ag-citrate NPs

Widely used in consumer products

 Effects of ionic strength, pH  Stability of suspension:

Amino acid adsorption
Surface charges
Aggregation

http://pubs.acs.org/doi/full/10.1021/es1042832

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Determining Suspension Characteristics

http://en.wikipedia.org/wiki/File:DLS.svg

Spectrophotometry Dynamic Light Scattering

http://en.wikipedia.org/wiki/File:Spetrophotometer-en.svg

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Zeta Potential and Suspension Stability

http://www.bioresearchonline.com/article.mvc/Automated-Protein-Characterization-With-The-M-0002

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Environmental Thiol Concentrations

Bell, 1997

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Ag, L-Cysteine Complex Aggregation

Time (min) Samples: Ag NPs (1 mg/L), L-cysteine (10 mM), NaCl (10 mg/L)

pH < 8.0

pH > 8.0

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Ag-Cysteine Complex as Function of Ionic Strength, pH

Ag-Cysteine Absorption Spectra

0.05

0.05 0.1 0.15 0.2 0.25 200 400 600 800 1000

Wavelength (nm) Absorption

Ag Control (10mg/L) Cys pH 7.0 10mM NaCl Cys pH 9.0 10mM

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Formation Mechanism

Cohen-Atiya et al, Journ. Elec. Chem., 2002

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Cysteine Adsorption Conformation

Ag NP + + + + + + +

 Coadsorption of chloride ion with cysteine

SLIDE 12

12 Ag, L-Cysteine Particle Size

200 400 600 800 1000 1200 20 40 60 80 100 120 140 160

Time (min) Hydrodynamic Diameter (nm) Ag-Cys, pH 7.1, 1 mM NaCl Ag-Cys, pH 7.1, 10 mM NaCl

10 20 30 40 50 60 20 40 60 80 100 120 140 Time (min) Hydrodynamic Diameter (nm)

Complex Formation as a Function of IS

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Ag-Cysteine Complex in Environment

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Complex Characterization

Formation is highly dependent on pH, IS, and

concentration of L-cysteine

Chloride ions are coadsorbed on Ag surface with

cysteine

Complex results in aggregation or disaggregation of

NPs based on IS

Prevents stabilization by natural organic matter (NOM)

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Future Research

Environmental Scenarios - involving freshwater with

natural organic matter

Adsorption isotherms – characterizing the Ag-cysteine

complex formation as a function of cysteine concentration

Fate of Ag-cysteine complex

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Ag-Cysteine Count Rates, [NaCl]=10 mM

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