Hi

you can use the EDC-NHS chemistry to thiolate the nanoparticle surface.

then you can bind antibody on the nanopartilcle surface.

Hi,

First of all,please describe which techniques you have done. Have you used something like cysteine? In order to attach a linker to gold, it's better to use a thiol.

maybe it's better to change your synthesis procedure of Gold nanoparticles. You can use another stablizer instead of citrate.

good luck.

I have used EDC-NHS but still no luck ... The antibody is washed away:((

We produced aunp in two ways (electrode position n basic method for developing gold nano particle) either way it didn't work ... We even used pdda

Try 2-aminothiolan

Very simple... Use Dihydrolipoic acid, which has thiol terminal groups on one end and COOH groups on the other end. Thio groups will attach to gold while COOH will be extending outwards. Use EDC-NHS to conjugate these COOH groups to NH2 groups of antibodies. It must work

Is dihyrolipoic acid stronger than GSh ..... At the time being am using GSH but still everything is washed away

I believe it is much stronger binding, because each molecule of DHLA contains two thiol groups.

The purity of the gold is very important. If you have tiny amounts of contaminations you will not have a dense layer of the thiols, which will be immediately oxidized and leave the surface.

GSH as in glutathione? 

Conjugating NH2 groups on the antibodies to COOH via EDC-NHS would work, however this has a downside. The recognition sites of the antibody are at the antibody peptide chains N-terminals. Therefore it inevitable that some of the recognition sites will be blocked, leading to lower antibody activity. This method also leads to significant irreproducibility, as there are multiple antibody orientations possible. Linking via the C-terminals of the antibody peptide chains would therefore be a better method, as antibody C-terminals would be attached to the nanoparticles and recognition sites unblocked, leading to much greater antibody activity. This can be done by: 

I have recently done this successfully.

Yes :) GSH as gluthation

Dear Juantina

Thanx for the response .... What kind of a linker do u propose ??

You might want to change Glutathione. EDC-NHS chemistry will cause self binding between GSH molecules even before the Ab is added.

Replace it with a molecule that is restricted to two functional groups, such as the earlier suggested dihyrolipoic acid or one of the mercapto chemicals or something more convenient ( Amine + thiol ). 

Sorry I missed your question. We used cysteamine as the linker. It's amine moity reacts with the activated COOH leaving a thiolated antibody which readily bonds to the gold  through a AU-thiol bond. this is the smallest thiol- amine molecule and seems to work well. this also has the benefit that it results in very little change to the antibody and should minimise any interference with the antigen binding region and increase the binding region access by pointing it more up toward the solution.

Try this gold conjugation kit:

www.nanodiscoveryinc.com