Can anyone help me by sharing the procedure for radioactive Phosphorous - 32 (orthophosphoric acid-32) labeling onto the surface of Quantum dots?
Hi Mangaiyarkarasi. I love these type of questions because they are challenging and strange.
First of all, attaching 32PO4 to QDs will have to be through a linker attached to the QD that will bind PO4 tightly.
The easiest way I can think of is to couple Hg++ or Pb++ compounds to the QD surface and have the metal bind the PO4
Sigma has a host of mecapto or lead organic compounds that have -NH2 or -COOH functional groups that can be attached simply to the QD, if it has -NH2 or -COOH surface groups.
What is the surface chemistry of your QD?
If the QD does not have a -NH2 or -COOH surface groups, then you can use aminosilanes to introduce an -NH2 functional group onto the QD surface.
Respected Professor,
Thank you for your valuable answer. This will helps many of them who were working in quantum dots for radiation therapy.
Basically, I am using octadecane and dodecanethiol as a surfactant for synthesizing Quantum dots. As it is insoluble in water, the surface will be functionalized with 3-Mercaptpropionic acid for QDs dispersion in water.
I hope this will create the NH2 or COOH linkage on the surface of QDs.
Once again thank you, Professor, for your timely help.
Sincerely
Mangai
Hi Mangai, I have never synthesized QDs, but I have surface labeled a lot of them.
Since the surface is functionalized with mercaptoproionic acid, I assume that the surface has exposed -COOH groups that are held in place by S-S bonds via the dodecanethiol.
If so, there might be a problem with heavy metals being attracted to S-S bonds. I don't know how it will affect the coupling.
As for heavy metal linkers that can bind PO4, sigma has a number of amino-Me+2 compounds. You will have to look through Ksp tables of PO4-Me+2 to choose which ones are the tightest and can be purchased with a primary amine. Coupling an -NH2 to a -COOH is very easy and efficient using the zero-length EDC
The compounds that I found that look promising are:
http://www.sigmaaldrich.com/catalog/product/sial/10005?lang=en®ion=US
http://www.chemspider.com/Chemical-Structure.8082118.html
I am sure that there are more efficient ways to do this, so I think it is a good idea to direct your question to the organic chemistry and inorganic chemistry forums on RG.
Good luck,
Stenni
Respected Professor,
Thank you for your valuable reply in your busy schedule.
I will follow the procedures and study the binding mechanisms and if I may stumble in some part of the interaction, I will ask you the help.
Kindly help me, Professor.
Thank you once again for your support.
Sincerely
Mangai.R
Hi Mangai, I will help in any way I can, but please direct your question also to RG forums having organic chemist, inorganic chemists and QD specialists.
They may have more detailed knowledge of what you want to do and how to do it.
Stenni.
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