What kind of bonds it formed between quantum dots and their ligands? Are they hydrogen bond?
I want to modify PEI as the surface ligands to substitute OA/OAm on copper sulfide nanocrystals, however i do not know in which way to modify PEI.
Does anyone could tell me the mechanism of ligands attaching on quantum dots? How does people choose chemicals as ligands?
Please go through this paper and related references. It will definitely help you.
There is no general method for (quantum dot) bioconjugation. One of the best textbooks is
Bioconjugate Techniques (Third Edition)
Author(s): Greg T. Hermanson ISBN: 978-0-12-382239-0
Also, quantum dots are made from very different materials. Therefore, they need different protocols for conjugation. And finally, the kind of ligand defines, which approach is suitable. And not to forget the application, for which you want to use your quantum dots. PEI is a nice basis for some bioconjugation protocols, however, it may lead to heavy non-specific binding in some immunochemical applications.
It depends on the ligand type and on the material of quantum dots. For example, if quantum dot is composed of oxide, carboxylate ligand can be bonded by means of monodentate, bidentate chelating and bidentate bridging (see my article attached).
Best regards, Bartek
Often, the selection of ligands is based on the functionality of them. For instance, a ligand with amine, thiol, hydroxyl would be suitable for CdSe, CdS, PbSe....etc. The attachment is between the Cd(2+) in the case of CdSe and the nitrogen, or sulfur, or oxygen. i.e. the electron rich atom. The attachment occurs via a chemisorption process, and based on the literature the type of bond is covalent/ coordinated bond.
Octylamine, hexadecylamine, Polyethylene Glycol (PEG) might be good ligand to functionalise the QDs. The latter, is suitable for aqueous environments.
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