I have chemically synthesized silver nanoparticle to combat microbes on wound site. I have used many methods of synthesis, but I found minimal field of silver NP product.I am getting whitish precipitate if I target high yield using sodium borohydride and ethanol.
Is there any method that give high yield silver nanoparticles. I would also like to know the post processing steps after AgNP synthesis(drying, finding collidal NP concentration,resuspension), as many articles won't report those steps.
Dear Hari Prasath Nagaiah, many investigations witness precipitation is the best choice for high yield and easy synthesis technique. Please check the following documents and links. My Regards
https://doi.org/10.1155/2010/392572
https://doi.org/10.1039/C5RA20446A
https://doi.org/10.1155/2010/392572
https://www.researchgate.net/post/How_can_one_get_a_high_yield_of_plant_synthesized_silver_nanoparticles
Dear Hari Prasath Nagaiah, many investigations witness precipitation is the best choice for high yield and easy synthesis technique. Please check the following documents and links. My Regards
https://doi.org/10.1155/2010/392572
https://doi.org/10.1039/C5RA20446A
https://doi.org/10.1155/2010/392572
https://www.researchgate.net/post/How_can_one_get_a_high_yield_of_plant_synthesized_silver_nanoparticles
Alan F Rawle High yield I am mentioning here is the raw material (silver nitrate) to silver nanoparticle conversion. I am geting maximum product yield upto 6.5% i.e For 1 gram AgNo3 my yield is only 50 mg.
Hari Prasath Nagaiah
Where does the rest of the material go? When I was making sterically stabilized 'Ag nanoparticles' then I would aim for a loading of 5% and usually ended up with 4.5 - 4.7%; the remainder being lost on washing. The average particle size by number being around 10 nm. Can you elaborate on your method? Concentrations, pH control, stabilization etc? You can't dry a colloidal suspension of Ag nanoparticles and when you mention '50 mg', I suspect you're trying to do so.
Alan F Rawle
Yes, I used precipitation to dry silver nanoparticles purposely because I need accurate concentration of AgNP to do microbial assays.I can't measure nanoparticles in collidal form with appropriate technologies.
I synthesised silver nanoparticles using freshly prepared 0.01 M sodium borohydride and 0.01 M AgNo3 under vigorous stirring. Followed by addition of 25% absolute ethanol and reaction is done in closed amber container for 48 hrs @ 80°C. Centrifuged @7000 rpm for 30 mins and washed repatedly with water and ethanol and dried @80°C.
Other than this I have tried polyol synthesis, one pot synthesis, UV mediated synthesis, eventhough AgNP yield was very low.
Can I know the possiblities I can do to measure the collidal silver nanoparticle suspension. Can I measure the concentration using UV-Spectrometry
Please suggest any method with high silver nanoparticle production and post processing steps to concentrate AgNP/Measure synthesised collidal solution
Hari Prasath Nagaiah
Your method has zero chance of producing silver nanoparticles, IMHO. Your sentence 'I need accurate concentration of AgNP to do microbial assays' is not logical. You cannot preserve the nano nature of your material by drying. Period.
The usual route to measurement of silver concentration is dissolution in nitric acid and then measurement via ICP or AAS. Yes, UV-VIS can be used to measure the concentration of silver nanoparticles - for that you'll need standards of known concentration and interpolate within.
View the webinars I sent you (registration needed):
Silver colloids and invisible ink
https://www.malvernpanalytical.com/en/learn/events-and-training/webinars/W150902SilverColloidInvisibleInk.html
Metal colloids - their preparation, application and characterization
https://www.malvernpanalytical.com/en/learn/events-and-training/webinars/W160218MetalColloids.html
Dispersion and nanotechnology
https://www.malvernpanalytical.com/en/learn/events-and-training/webinars/W190528DispNanoMat
Alan F Rawle
Sodium borohydride acts both as a reducing and stabilizing agent for AgNP synthesis. I have confirmed synthesis using UV Spec wavelength scan from 350 to 650 nm and obtained narrow peak @410 nm. Conformed its higher antimicrobial activity with bacteria. Then what's the possibility that the received particles are not AgNPs.
Hari Prasath Nagaiah
Your prepared silver nanoparticle colloidal suspension should be transparent (probably colored brown). You may be able to absorb this onto a suitable substrate e.g. textile, bandage (or in my case silica). Better is to take a dried substrate of known pore volume and absorb dilute (1% say) ammoniacal silver nitrate on it sufficient to saturate the pores. Then reduce with hydrogen or hydrazine hydrate - the former gives you 100% yield (no silver lost), the latter loses some silver in the washing stage. I have used borohydride reduction and all my products were heavily contaminated with intractable boron which acts as a poison for many subsequent applications. You need to measure the specific surface area of your preparation and it should be more than ~ 400 m2/g (60 X density of silver) to be nano.
Alan F Rawle Thanks for your valuable suggestion, sir. I have another doubt regarding polyol synthesis. When synthesizing nanoparticles with glucose as a reducing agent and PVP as a stabilizing agent. I observed color change for 30 mins. The color changes as transparent-mild yellow-dark yellow-brown. My doubt here is at which stage should I stop the reaction.
It is good to use colloidal nanoparticles rather than precipitated nanoparticles but how can I remove the unreacted products and contaminants from the obtained colloidal nanoparticles.
Hari Prasath Nagaiah
The color change is indicating growth/aggregation of the nanoparticles. Separation is normally by centrifuge. I never had that issue with low concentrations of silver nitrate.
The small nanoparticles were prepared by the Brust–Schiffrin method or its modification.
Sol–gel micro reactors (5-50nm)
Article Submicrometer intermediates in the citrate synthesis of gold...
PVD into liquid substrate (2-10nm)
Article Stabilization of sputtered gold and silver nanoparticles in ...
Reduction process (2-40nm)
Article Homogeneous Pd nanoparticles produced in direct reactions: G...
γ-Irradiation (3-30nm)
Article Synthesis of Cu nanoparticles using gamma-ray irradiation re...
Biosynthesis (9-25nm)
Article Banana peel extract mediated synthesis of gold nanoparticles
The green methods based on biosynthesis are environmentally friendly and also have potential high yields for particular types of nanoparticles
- Badges
- Science topic
- Similar topics
- Chemistry
- Nanotechnology
- Nanostructured Materials
- Nanoparticles