There are many procedures out there: TGA, ICP-MS, NMR these are all post process. But what is a good method to estimate the extent of ligand required for functionalization?
If we know the size of the nano particle and hence the surface area is there a method to arrive at a number by looking at the surface area of the functional group attaching to the surface of the nanoparticle?
This is a key problem for me since I synthesize custom ligands for specific uses, I would like to reduce the waste of material during functionalization.
Give me your general or specific (to any particular nanoparticle) comments.
For a rough estimation purpose, I would suggest to divide the surface area of the particle by the cross sectional area of the ligand (the projection area of each molecule).
Hi Prem, I have functionalized carbon nanotubes, fluorescent particles and quantum dots and I have to say that there is no set formula for this.
You have to use different conjugation chemistries with different functional groups with different ligands.
In my experience, optimization of ligand densities is empirical.
Hi,
Ligand grafting on the surface of gold nanoparticles has been studied extensively. It is possible to arrive at an estimate from the nanoparticle surface area. Here are some of those resources.
This article shows that a maximum of 1.13 molecules of PEG5000 can be functionalized per nm2 of gold nanoparticle [1].
[1] Article Polyethylene glycol functionalized gold nanoparticles: The i...
The supplementary material of the following article provides necessary information for calculating density of PEG at the surface [2].
[2] Article Targeting kidney mesangium by nanoparticles of defined size
Prediction of ligand requirement, for functionalization reaction, depends on many factors: the functionalization chemistry and its efficiency, degree of functionalization required at the surface, Size and nature of the ligand, Porosity of the nanoparticle, possibility of the ligand diffusing into the nanoparticle, etc.,. More the knowledge on nanoparticle, ligand and functionalization method, better it could be predicted.
Best Wishes.
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