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Hi everybody;
I want to find young modulus of OB6 cells by using AFM. I was wondering which tip is the best tip for me?
I am going to do the experiment on Fluid cell.
previously, I did this test in air by using SNL-10 tips (D and C) and on separation- force curve I got large negative deatach force. I do not know what was the reason.
Another question is I am using SPIP software to analize my data and it automatically gives sensitivity, I do not konw it is reliable or not. if some one has a idea please let me know about that.
Thanks for helping.
Ashkan
SNL probes are not specific to any one mode of operation. They are widely used for contact mode, tapping mode and force measurements.
Because they are especially sharp, SNL probes may not be the best choice for live cell imaging. Our DNP probes are better suited for that since they are somewhat less sharp and therefore less likely to puncture, tear or otherwise damage the cells. But if the cells are fixed or naturally more robust then the SNL probes can work.
In any case, you will want to choose a soft cantilever (for SNL or DNP, the long thin 0.06 N/M one). Scan slow (<0.5 Hz) and try to keep the setpoint low (i.e. the imaging force low).
Regards,
-Ben
Hi Ashkan,
On the Bruker AFm probes website is actually a nifty AFM probe selector utility. It can be found here: http://www.brukerafmprobes.com/category-list.aspx?CategoryID=265
So, yes the SNL probes may be used in fluid for contact imaging on the MM but may be too sharp for imaging of living cells.
Stefan
Thanks...
I will let you know about my results.
I will have a look at your AFM images tomorrow but would like to add a few comments:
- Ang is right: SNL probes are usually not good for living cells for the reason he mentionned.
- If you want to image in contact mode, DNP D (0.06 N/m) can be used, as well as OBL B (0.006 N/m) which are the softest exisisting ones on the market. So they are excellent if you want to minimize the loading forces on the samples. But they suffer from 2 main drawbacks: you might have to wait at least 30 min (thermal equilibration) before engaging and the lever is rather short so if your cells are higher than 3 um you might come accross scanning artifacts. This is the reason why OBL B which are even shorter, should not be used.
- If you want to image in tapping mode, DNP A (0.35), B (0.12) and C (0.24) are quite good. The right peak should be around 8 to 12 kHz;
- If you want to image in Peak Force Tapping, I recommend OBL probes for very soft cells and ScanAsyst Fluid probes for rather stiff cells (100 kPa and more).
Good luck!
Alex.
Something that can be helpful regarding how you can clean the MM fluid cell after use. I got the question from a customer today but I think it can help many users:
For people who work on lipid monolayers, bilayers or cells here is a gentle and efficient way to wash your fluid cell: remove the connectors and put it in a clean vessel like a glass beaker. Add a few droplets of detergent (you can use a regular dish-washer detergent) and fill it with ultrapure water. Then reput the connectors including the perfusion tubes and use a syringe to pump the liquid in and out the pipes. You can also use a soft toothbrush to clean the area close to the spring. Then rinse many times with ultrapure water until the foam has totally gone.
Thanks again