I need to synthesize gold nanoparticles below 20 nm size and monodisperse for drug delivery application. I have read many articles and follow the same procedure but every time I got different results. I need to know that how I will get same results every time with 20 nm size. I also want to know that what ratio of citrate/gold chloride, What pH and temperature, I need to consider for the same.
Thanks with Regards
Hey Vikas,
AuNPs synthesis with Na-Cit is very well known and established method. it must give the proper result. even though if you are saying that you are not getting similar results, i would suggest the following point to take care of.
1. AuNPs are very very sensitive, so every time you prepare AuNPs, make sure your glass wareare washed properly with aquaregia and dried properly.
2. water you are using must be milli-Q water or double distilled water and should not contain any sort of impurities or turbidity.
3. Na-Cit you are using should be pure and weighed accurately.
4. HAuCl4.3H2O is highly higroscopic, hence must be taken care while weighing. make sure you put some teflon tape on the spetula while weighing the Auric acid to avoid any sort of impurities.
one more thing i would like to add is that, you will not get all the particles of the same size ever.
There will be range, for ex. 10-20 nm or 30-40 nm.
you can get all similar size of nanoparticles in a signle image, but through out the solution, there will be different sizes of the gold nanoparticles.
If you want a particular size of nanoaparticle for the specific application, then i would suggest to filter nanoparticles through desired pore size filter paper.
I hope this will help.
Best of luck.
Thanks Dr. Gaurav, Could you please suggest me the ratio and concentration of gold chloride and citrate. How much conc. and ratio should I use for the synthesis of gold nanoparticles from 10-20nm range ?
Thanks in advance
Dear Vikas,
Go through the articles suggested by Dr. John Clarkson in previous answer carefully. you will get ratio and concentration of all size of AuNPs.
Also you can follow the below article for synthesis of 10-15 nm sized AuNPs.
Article Colorimetric detection of mercury(II) in aqueous media with ...
Vikas Shukla I have used a protocol from a Mirkin paper following the Turkevich method for making 13 nm AuNPs. It can be found here, steps 1-11: https://www.nature.com/articles/nprot.2006.51
HOWEVER, I also strongly recommend a slight change. Note: the tricky part of this synthesis is adding the sodium citrate solution quickly enough. If it is poured slowly, particles of varying sizes will result. The solution needs to be added all at once, to give consistent nucleation of the NPs.
This paper I've linked recommends for a 500 ml batch to prepare 50 ml of 38.8 mM sodium citrate tribasic dihydrate in Nanopure water, and adding that to gold solution once it is refluxing at 1 drip/sec. However, it is difficult or impossible to add 50 ml quickly (without pouring). Solution: Dissolve the same amount of sodium citrate as is in the 50 ml solution in 800 ul Nanopure water instead. It will just barely but completely dissolve. Use a 1 ml pipette to take up entire solution and pipette it in rapidly once gold chlorate is refluxing appropriately. The volume of liquid the citrate takes up does not matter. Only the amount of citrate matters. NPs produced by this method are very uniform and about 13 nm in size. See the attached TEM image below of the AuNPs produced using this modified method.
It took me six years of making batches of AuNPs to figure this out. I hope you find it useful.
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