- #1
R0WDY
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Hi everyone,
This is my first thread so I'll try to be as clear as possible and try to follow the rules.
My job is to synthesize silver nanoparticles, characterize them (TEM, DLS, EDAX, Z-POT), and then pass then on to the toxicologists. This is my thesis work to graduate.
A new thing I have been trying to synthesize is silver nanoparticles by using green tea extract. (-) epicatechin. (we have found that cells undergo oxidative stress per western blots, and using a biocompatible reducing equivalent will reverse toxicity) Toxicity assays we have performed support this hypothesis.
http://en.wikipedia.org/wiki/Catechin (slightly soluble in water, completely soluble at 70 degrees for the solutions I'm working with)
So far I have designed the experiment, such that I can produce nanoparticles of small size and with a poly-phenol coating. The issue at hand is inability to control variability in particle size and the presence of an insoluble compound. Here is the protocol I wrote:
Prepare .0025N Silver Nitrate solution (low concentration keeps ions in solution spread out to promote small particle size.
Prepare .005M (-) epicatechin solution (keep at 80-90 degrees C)
Place silver nitrate solution in ice bath with rapid stirring. (this will make excess reducing equivalent insoluble after quickly reacting)
Add hot reducing equivalent dropwise in 3:1 molar ratio (epi:Ag)
Allow to sit for 3 hours in icebath.
Sonicate reaction vessel, then transfer mixture to dialysis bags.
Dialysis at room temperature for 2 days (changing water every 8 hours)
Dialysis at 90 degrees C to remove Reducing equivalent for 4 days (changing every 8 hours)
Obtain nanomaterials from dialysis and run characterization.
Prepare a stock solution and determine concentration; pass to toxicologists.
I'd love to hear some ideas on how to better control my particle sizes. I'm getting a mean particle size of around 25nm with a standard deviation of 20nm, and its a major pain to keep rerunning the procedure. As far as the unknown insoluble organic material, I think it might be a byproduct of the epicatechin undergoing oxidation. Maybe there is a polymerization reaction happening that I'm unaware of?? According to EDAX indicates presence of C,O, and Ag. (H does not show up on our EDAX instrument)
Thanks everyone!
R0WDY
This is my first thread so I'll try to be as clear as possible and try to follow the rules.
My job is to synthesize silver nanoparticles, characterize them (TEM, DLS, EDAX, Z-POT), and then pass then on to the toxicologists. This is my thesis work to graduate.
A new thing I have been trying to synthesize is silver nanoparticles by using green tea extract. (-) epicatechin. (we have found that cells undergo oxidative stress per western blots, and using a biocompatible reducing equivalent will reverse toxicity) Toxicity assays we have performed support this hypothesis.
http://en.wikipedia.org/wiki/Catechin (slightly soluble in water, completely soluble at 70 degrees for the solutions I'm working with)
So far I have designed the experiment, such that I can produce nanoparticles of small size and with a poly-phenol coating. The issue at hand is inability to control variability in particle size and the presence of an insoluble compound. Here is the protocol I wrote:
Prepare .0025N Silver Nitrate solution (low concentration keeps ions in solution spread out to promote small particle size.
Prepare .005M (-) epicatechin solution (keep at 80-90 degrees C)
Place silver nitrate solution in ice bath with rapid stirring. (this will make excess reducing equivalent insoluble after quickly reacting)
Add hot reducing equivalent dropwise in 3:1 molar ratio (epi:Ag)
Allow to sit for 3 hours in icebath.
Sonicate reaction vessel, then transfer mixture to dialysis bags.
Dialysis at room temperature for 2 days (changing water every 8 hours)
Dialysis at 90 degrees C to remove Reducing equivalent for 4 days (changing every 8 hours)
Obtain nanomaterials from dialysis and run characterization.
Prepare a stock solution and determine concentration; pass to toxicologists.
I'd love to hear some ideas on how to better control my particle sizes. I'm getting a mean particle size of around 25nm with a standard deviation of 20nm, and its a major pain to keep rerunning the procedure. As far as the unknown insoluble organic material, I think it might be a byproduct of the epicatechin undergoing oxidation. Maybe there is a polymerization reaction happening that I'm unaware of?? According to EDAX indicates presence of C,O, and Ag. (H does not show up on our EDAX instrument)
Thanks everyone!
R0WDY
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