I want to prepare the silica and Fe3O4 nanoparticles modified with silane coupling agents like 3-Aminopropyltriethoxysilane (APTES).
What's the best solvent for coupling APTES on silica or Fe3O4 nanoparticles? Why?
Mahdi - I don't have any first hand experience with Fe3O4, but have worked extensively with silica in this context. I believe the answer to your question depends in part on how precisely you need to coat the particle surface. The ethoxy groups in APTES are sufficiently avid leaving groups that the molecule will polymerize in the presence of even trace amounts of water. The 'cartoon' version of ATPES coating onto silica usually shows spontaneously polymerization of APTES molecules that then encounter the silica surface and 'pile on.' This is definitely effective at amino functionalizing the surface, but the smoothness and long-term stability of the resulting particle can be a problem. Check Hermanson's textbook on bioconjugate techniques for a couple of approaches with APTES. One will likely work. Also, if you haven't seen them before, Bang Laboratories in the United States has a very useful collection of technical notes on their website that might provide clues for both silica and iron.
Best, John
Mahdi - I don't have any first hand experience with Fe3O4, but have worked extensively with silica in this context. I believe the answer to your question depends in part on how precisely you need to coat the particle surface. The ethoxy groups in APTES are sufficiently avid leaving groups that the molecule will polymerize in the presence of even trace amounts of water. The 'cartoon' version of ATPES coating onto silica usually shows spontaneously polymerization of APTES molecules that then encounter the silica surface and 'pile on.' This is definitely effective at amino functionalizing the surface, but the smoothness and long-term stability of the resulting particle can be a problem. Check Hermanson's textbook on bioconjugate techniques for a couple of approaches with APTES. One will likely work. Also, if you haven't seen them before, Bang Laboratories in the United States has a very useful collection of technical notes on their website that might provide clues for both silica and iron.
Best, John
In general Silica particles can be coated with APTES in ethanol solvent using aquesous ammonia. Here, the thickness of the layer is controlled by tuning the traces of water and pH.
Depends on what your application is and what you surface density should be. Water would work best especially with some modification of the procedure. There is a danger of aggregation if your particles end up with an IEP close to the pH of the solution. You can solve this by pH control.
However, trace amounts of water in a different solvent would also lead to surface conjugation of APTS as stated above.
One small note. There is also APTMS which hydrolyses quicker (relative to APTES) so it can be another tool you can potentially use.
Coating of APTES is done by using acetonitrile, DMF for biomedical application.
The best and green way to coupling APTES with Fe3O4 particles is to use 20:1 volume ratio of ethanol : water as solvent under ultrasonic agitation to avoid aggregation and agglomeration of particles. Following papers can help more:
Article Novel magnetic amine functionalized carbon nanotube/metal-or...
Article Laccase immobilized manganese ferrite nanoparticle: Synthesi...
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