Hello, I am interesting to make a research about AgNP antibacterial activity using the green synthesis method for my thesis. I've read from several publications, they use various concentrations. It's my first time to do research with nanoparticles.
Let's say, I will synthesis the AgNP with mixing aqueous garlic extract (1 ml) to 1 mM AgNO3 (19 ml). What I want to ask for help are:
1. I would like to know, how to make the various concentration ranging from 100 µg/ml to 6.25 µg/ml from that AgNP solution?
2. Can I dilute the synthesized AgNP with distilled water? Like when we dilute plant extract.
Thank you very much in advance.
Dear Khairunnida Rahma ,
first of all, the overall answer: yes, you can dilute AgNPs solution by water to obtain needed concentration.
BUT... From my point of view, such volumes of reagents are not correct - conversion of reaction may be not 100 %, then you will obtain solution of AgNPs and Ag+ and results of antimicrobial studies will not be correct. But I can be wrong because I didn't know concentration of garlic extract...
In any case, it is one hint to simple testing of conversion of Ag+ into AgNPs: after "green" synthesis you can record UV/vis spectrum of solution; after that into the cuvette (or into sample taken) you must add the excess of solution of strong reducing agent (NaBH4 or N2H4) and record spectrum one again. If you will not observe any changes then - my congratulations! You obtained solution of AgNPs without Ag+! But if you will observe increasing of optical density then you will need to increase the time of synthesis and/or concentration of garlic extract.
With kind regards,
Liliya
Khairunnida Rahma
You can dilute with water and garlic extract. With the garlic extract, the nanoparticles will be more stable. When diluted with water, they can settle. But when diluted with garlic extract, you may be told that the bacteria died from the garlic extract, and not from the nanoparticles. Better to do comparative research, if possible.
Dear Khairunnida Rahma ,
first of all, the overall answer: yes, you can dilute AgNPs solution by water to obtain needed concentration.
BUT... From my point of view, such volumes of reagents are not correct - conversion of reaction may be not 100 %, then you will obtain solution of AgNPs and Ag+ and results of antimicrobial studies will not be correct. But I can be wrong because I didn't know concentration of garlic extract...
In any case, it is one hint to simple testing of conversion of Ag+ into AgNPs: after "green" synthesis you can record UV/vis spectrum of solution; after that into the cuvette (or into sample taken) you must add the excess of solution of strong reducing agent (NaBH4 or N2H4) and record spectrum one again. If you will not observe any changes then - my congratulations! You obtained solution of AgNPs without Ag+! But if you will observe increasing of optical density then you will need to increase the time of synthesis and/or concentration of garlic extract.
With kind regards,
Liliya
Variations in concentrations of silver nanoparticles could be obtained by varying the concentrations of the reducing agent. Please see the attached links:
https://www.nature.com/articles/s41598-018-30317-9. Article Low Concentration of Silver Nanoparticles Not Only Enhances ...
https://www.jmaterenvironsci.com/Document/vol8/vol8_N11/436-JMES-3502-Ismail.pdf.Article Ag + reduction and silver nanoparticle synthesis at the plas...
Hi
Antibacterial properties of Ag NPs is size and concentration dependent.
As the conversion is not 100%, the best way is doing ICP and TEM to estimate the mass concentration of the as-synthesized Ag NPs with specific size accurately. Then, dilution with water (after centrifugation as purification step).
A rough estimation also is monitoring the LSPR peak of Ag NPs during the synthesis and assuming 100% conversion when the intensity remains constsnt. Dont forget the purification step.
Regards,
Mohammad
Liliya Bazylyak
Adding re-reducing agent is a good answer. You are smart.
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