Great video! There needs to be more sample preparation videos online for different types of samples. It's very hard to learn when everyone is so secretive about their techniques! :)
Dear Marjan Shinwari, We do not have experience with the carbon dots. Unlike gold, carbon is a low Z material and many things need to be considered for making a good TEM sample. May be Carbon dot related literature or people working actively in this field would be helpful.
It's a very nice video. Very much helpful for me, thank you. Can you please tell me about the conditions (minimum) required to visualize the nanoparticle under SEM. (Like voltage and Magnification)
Dear Punit, Thanks for your comment. There is no strict condition/rule to see these nanoparticles under SEM. You can see these nanoparticles easily under SEM
Very nice and useful video. I just have some questions: 1. On which side of the grid did you load your sample (dark or bright side? and what's the difference between the two sides?. 2. what's the best way to prepare CTAB gold nanorods sample for TEM? Thank you very much and your effort is very appreciated.
1. It depends on a sample type. For citrate Au NPs sample, using method # 3, both sides of a Cu-grid has their advantages and disadvantages. While transferring the blue-film onto a Cu-grid, use of a dark side allows less tearing of a carbon film, but more uniform dispersion of the citrate NP was found when bright side was used. (NB: various factors come into play such as force applied while transferring NPs onto a grid, amount of liquid in a blue film, etc. NP sample preparation for TEM depends on types of solvent used. Not sure, What solvent was used for CTAB Au NRs? what color of film was observed when you dry a drop of CTAB NRs?
chakraprasadjoshi Thanks for the answer. 1. The solvent of CTAB NRs is water. 2. I used to prepare the sample the same way as described in method#1 (put drop on the bright side of the grid) but it did not give me that quality of image that I want. When I switched to the dark side of the grid it got better, so I was wondering what could be the difference between the two sides of the grids!. 3. I am supposed to do TEM for my NRs soon so I will try method#3. But I am not sure which side of the grid should I use. 4. I do not know the color of the film as I have not tried it yet but I think it is blueish - violet as this is how my NRs look like when they aggregate (blueish).
Method # 1 might not be the best way for TEM sample preparation of aqueous NPs due to hydrophobicity of a carbon film. Method # 2 & 3 may be more useful. However, challenge would be a sample burning (i.e., brightening or darkening of the exposed sample area under the electron beam at a higher magnification) due to excess CTAB. Sample burning can be minimized by rinsing Cu-grid -- that contains dry NRs -- with acetone or ethanol before imaging the sample. In our case it worked as we tried to image TOAB Au NPs in toluene. Well not completely sure, how it will work for your sample Mohamed. Give a try and please let us know your problems/success.
Well Sharang, it depends on what we want. For nanoparticle size analysis, we want the best image. If sample is wet, we can see the nanoparticles moving from one place to another under the electron beam and captured images may not be a good one. Therefore, we want a dry sample where particles remain rigid. We have done the imaging right after transferring the nanoparticles onto a grid. Most of the windows are wet, however, we search for those windows in a grid that are dry enough to image. Sometimes it works. We can also do ambient instead of Vacuum drying. Drying time would depend on the ambient conditions (roughly 6-12 hrs.).
Very nice video,at the moment I'm dealing with the same problem and not sure If I could use your method or not. I have 1ml of Phosphate buffered saline (0.01M;Merck,P-3813) which I suspect the presence of nano-micro sized particles of copper ,copper oxide or platinum within. The amount of particle should be really low since in this case, particles are somehow an unwanted byproduct of the test setup.(maybe some nano gram) Im gonna perform XPS and SEM on the prepared samples afterward therfore Im planning to leave the NP on nickel grid coated with carbon!! I would be happy if you could help me in this , in the case you have any suggestion or hint,Thank you in advance
General test: Color is an important property of the nanoparticles (NPs). If you think your electrolyte solution has NPs in it, it might give color to your electrolyte solution which can be characterized using UV-vis spectroscopy. By the way, what kind of color your electrolyte solution (with NPs) has?
chakraprasadjoshi Thank you for this hint,I have not characterized it yet,using UV-vis spectroscopy ! So,it makes more sense to do this step first.(The elecrolyte itself is just as it was before the experiment,colorless)
Not sure about the purpose. However, ambient or vacuum drying will work for preparing the nanocrystals sample (on a Cu-grid for electron microscopy) dispersed only in water.
I want to image my Pt nanoparticles that were prepared in ethyleneglycol and capped with PVP. I prepare them in high concentration, and hence, for TEM, I dilute them 20 times with ethanol, but most of the time I got agglomerates using drop coating method. Do you suggest using water instead of ethanol? do you think method 3 will work with ethanol. Thanks in advance.
Hi Ehab, dry sample is important for TEM imaging. Ethylene glycol might not be a good solvent because it is difficult to dry while preparing TEM samples. Ethanol and water could be a better choice. By the way, are they soluble in water only?
chakraprasadjoshi First, thank you for the video and your reply. My samples in ethanol were prepared originally in 1,5-Pentanediol (or ethyleneglycol) at high conc. and then diluted 20 times with ethanol only for TEM sampling purpose. I think, the 5% of 1,5-Pentanediol should not affect the overall boiling point of the mixture (for example 10% ethylene glycol in water boiling point is 102 C instead of 100 for pure water). Therefore, I think the problem is not in the 1,5-Pentanediol, but may be the hydrophopicity of the carbon film on the copper grid or the interaction of water/ethanol with capping agent allowing for agglomeration. The NPs are suspended in 1,5-Pentanediol and capped with PVP. Therefore, it forms a homogenous mixture with water and most of the alcohols and when I want to precipitate them I use acetone as it has a higher ability to remove the PVP.
Hi Ehab, just want to understand your problem better. Your goal is to image Pt nanoparticles capped with PVP and dispersed into 1, 5 pentanediol, right?
Well Ehab, your problem is also new for us. It would be useful to know whether method 3 works for your sample or not. Give a try and let us know, although the diols could pose a challenge while drying samples.
Great video! There needs to be more sample preparation videos online for different types of samples. It's very hard to learn when everyone is so secretive about their techniques! :)
We are glad that our video is useful to someone. Thanks
chaotic sample prep, beautiful image
Looks nice, but would likely damage a thin carbon film for HR-TEM. Better to activate the surface with an air plasma to render hydrophilic?
Great video...Can you kindly suggest me how to prepare TEM sample for carbon dots...I have tried many times but not getting satisfactory results...
Dear Marjan Shinwari,
We do not have experience with the carbon dots. Unlike gold, carbon is a low Z material and many things need to be considered for making a good TEM sample. May be Carbon dot related literature or people working actively in this field would be helpful.
@@chakraprasadjoshi okay thanks alot😊
used method #3 and it worked well for me, thanks
It's a very nice video. Very much helpful for me, thank you. Can you please tell me about the conditions (minimum) required to visualize the nanoparticle under SEM. (Like voltage and Magnification)
Dear Punit,
Thanks for your comment. There is no strict condition/rule to see these nanoparticles under SEM. You can see these nanoparticles easily under SEM
Very nice and useful video. I just have some questions:
1. On which side of the grid did you load your sample (dark or bright side? and what's the difference between the two sides?.
2. what's the best way to prepare CTAB gold nanorods sample for TEM?
Thank you very much and your effort is very appreciated.
1. It depends on a sample type. For citrate Au NPs sample, using method # 3, both sides of a Cu-grid has their advantages and disadvantages. While transferring the blue-film onto a Cu-grid, use of a dark side allows less tearing of a carbon film, but more uniform dispersion of the citrate NP was found when bright side was used. (NB: various factors come into play such as force applied while transferring NPs onto a grid, amount of liquid in a blue film, etc.
NP sample preparation for TEM depends on types of solvent used. Not sure, What solvent was used for CTAB Au NRs? what color of film was observed when you dry a drop of CTAB NRs?
chakraprasadjoshi
Thanks for the answer.
1. The solvent of CTAB NRs is water.
2. I used to prepare the sample the same way as described in method#1 (put drop on the bright side of the grid) but it did not give me that quality of image that I want. When I switched to the dark side of the grid it got better, so I was wondering what could be the difference between the two sides of the grids!.
3. I am supposed to do TEM for my NRs soon so I will try method#3. But I am not sure which side of the grid should I use.
4. I do not know the color of the film as I have not tried it yet but I think it is blueish - violet as this is how my NRs look like when they aggregate (blueish).
Method # 1 might not be the best way for TEM sample preparation of aqueous NPs due to hydrophobicity of a carbon film. Method # 2 & 3 may be more useful. However, challenge would be a sample burning (i.e., brightening or darkening of the exposed sample area under the electron beam at a higher magnification) due to excess CTAB.
Sample burning can be minimized by rinsing Cu-grid -- that contains dry NRs -- with acetone or ethanol before imaging the sample. In our case it worked as we tried to image TOAB Au NPs in toluene.
Well not completely sure, how it will work for your sample Mohamed. Give a try and please let us know your problems/success.
Is vacuum drying important ? Can ambient drying be used ? if yes then have you noted the duration in hours it takes ?
Well Sharang, it depends on what we want. For nanoparticle size analysis, we want the best image. If sample is wet, we can see the nanoparticles moving from one place to another under the electron beam and captured images may not be a good one. Therefore, we want a dry sample where particles remain rigid.
We have done the imaging right after transferring the nanoparticles onto a grid. Most of the windows are wet, however, we search for those windows in a grid that are dry enough to image. Sometimes it works.
We can also do ambient instead of Vacuum drying. Drying time would depend on the ambient conditions (roughly 6-12 hrs.).
Thank you so much for sharing. I was able to make better sample of my nanoparticles
Very nice video,at the moment I'm dealing with the same problem and not sure If I could use your method or not.
I have 1ml of Phosphate buffered saline (0.01M;Merck,P-3813) which I suspect the presence of nano-micro sized particles of copper ,copper oxide or platinum within. The amount of particle should be really low since in this case, particles are somehow an unwanted byproduct of the test setup.(maybe some nano gram)
Im gonna perform XPS and SEM on the prepared samples afterward therfore Im planning to leave the NP on nickel grid coated with carbon!! I would be happy if you could help me in this , in the case you have any suggestion or hint,Thank you in advance
If we understand correctly, you want to confirm whether there are nanoparticles or not in your phosphate buffer sample. Is that right?
chakraprasadjoshi Yes,as I said there might be byproduct left within the elctrolyte which their presence need to be confirmed .
General test:
Color is an important property of the nanoparticles (NPs). If you think your electrolyte solution has NPs in it, it might give color to your electrolyte solution which can be characterized using UV-vis spectroscopy. By the way, what kind of color your electrolyte solution (with NPs) has?
chakraprasadjoshi Thank you for this hint,I have not characterized it yet,using UV-vis spectroscopy ! So,it makes more sense to do this step first.(The elecrolyte itself is just as it was before the experiment,colorless)
My nanocrystal dispered only in water, then how can I dry the sample?
Not sure about the purpose. However, ambient or vacuum drying will work for preparing the nanocrystals sample (on a Cu-grid for electron microscopy) dispersed only in water.
I want to image my Pt nanoparticles that were prepared in ethyleneglycol and capped with PVP. I prepare them in high concentration, and hence, for TEM, I dilute them 20 times with ethanol, but most of the time I got agglomerates using drop coating method. Do you suggest using water instead of ethanol? do you think method 3 will work with ethanol. Thanks in advance.
Hi Ehab, dry sample is important for TEM imaging. Ethylene glycol might not be a good solvent because it is difficult to dry while preparing TEM samples. Ethanol and water could be a better choice. By the way, are they soluble in water only?
chakraprasadjoshi First, thank you for the video and your reply. My samples in ethanol were prepared originally in 1,5-Pentanediol (or ethyleneglycol) at high conc. and then diluted 20 times with ethanol only for TEM sampling purpose. I think, the 5% of 1,5-Pentanediol should not affect the overall boiling point of the mixture (for example 10% ethylene glycol in water boiling point is 102 C instead of 100 for pure water). Therefore, I think the problem is not in the 1,5-Pentanediol, but may be the hydrophopicity of the carbon film on the copper grid or the interaction of water/ethanol with capping agent allowing for agglomeration. The NPs are suspended in 1,5-Pentanediol and capped with PVP. Therefore, it forms a homogenous mixture with water and most of the alcohols and when I want to precipitate them I use acetone as it has a higher ability to remove the PVP.
Hi Ehab, just want to understand your problem better. Your goal is to image Pt nanoparticles capped with PVP and dispersed into 1, 5 pentanediol, right?
chakraprasadjoshi Yes, this is the target.
Well Ehab, your problem is also new for us. It would be useful to know whether method 3 works for your sample or not. Give a try and let us know, although the diols could pose a challenge while drying samples.
nice