Hi, is there any methodology to be followed for sample preperation with respect to Nanoparticles as powder for TEM analysis? Whether the entrapped drug in the Nanoparticles will be visible if we perform the TEM analysis?
Dear Ramkumar,
The protocol which I follow is to first check the dispersion of the nanoparticles in different solvents like water, 2-propanol, ethanol etc. The different dispersions are ultrasonicated to separate the particles and the most stable dispersion is chosen for TEM characterization . Now, a drop of the stable solution is taken on the TEM grid and dried in a vacuum oven. Finally, the grid is inserted in the TEM machine.
However, in case of the drug loading, I dont think TEM micrographs can be very helpful to show the drug encapsulation. It will be better if you take the TEM image of your nanoparticles before and after drug encapsulation. Then may be from the size difference due to the adsorption of the drugs you can figure out the drug encapsulation.
Hope it helps.
You can sonicate the powder in buffer and then do drop coating for TEM. But I think it is difficult to understand the drug entrapment although you may get an idea if the size alters.
Dear Ramkumar,
The protocol which I follow is to first check the dispersion of the nanoparticles in different solvents like water, 2-propanol, ethanol etc. The different dispersions are ultrasonicated to separate the particles and the most stable dispersion is chosen for TEM characterization . Now, a drop of the stable solution is taken on the TEM grid and dried in a vacuum oven. Finally, the grid is inserted in the TEM machine.
However, in case of the drug loading, I dont think TEM micrographs can be very helpful to show the drug encapsulation. It will be better if you take the TEM image of your nanoparticles before and after drug encapsulation. Then may be from the size difference due to the adsorption of the drugs you can figure out the drug encapsulation.
Hope it helps.
For your case, atomic force microscopy (AFM) would be much better if you want to image both nanoparticles and drug. In a vacumm and electron beam environment for TEM measurements, most organic or biological molecules are usually burned out by electron beam. I hope this is helpful for you.
Does "entrapped" means your particles are hollow? If electron densities of particle shell and drug are different, you can see the difference if particle is big enough (100 nm and bigger, but it is microscope-dependent value).
You need to be more specific in what your nano-particles are. Do you mean they are liposomes with your drug trapped in the intenal compartment. Or are they some other type of particle (graphene folded, carbon cage)?
You can so some sort of drop coating on a grid, but they do need to dry to look at them in normal TEM.
To analyse them by cryo TEM, really they need to be soluble in water to get them in a vitreous ice layer. I've looked at some particles previously dissolved in organic solvents and the flash freezing just produced weird partitioning effects and general oddities.
Dear ramkumar,
sample preparation methods depends on the equipment. so you better know the method in general followed by the lab. we cannot find the entrapped drug in TEM in most of the cases.
regards
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