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Hello
I'm beginner user of Catalyst and I've worked little bit with force volume mode and PFQNM mode and done only Young modulus measurements.
I have to start adhesion measurement with fibronectin functionalization. Which cantilever is more suitable? With tip or tipless or even with sphere? In case of cantilever with sphere/bead - what sphere? Do you recommend Point and Shoot or Force volume measurement?
Is there any tutorial for Point and Shoot measurement? When I tried it, it seems that I have to take the image firstly and then I can pick up measurements points. Is there option without taking the image?
Thank you for all tips you can give me.
Jimmy
Hi Jimmy,
The choice of cantilever will revolve around a few things: resolution, spring constant, ease of functionalization...
1. For resolution you could use a sharp tip but this is usually not the best for funtionalizing as you may end up with too few bonding moieties at the tip end that can be damaged or wear quickly - hence a dulled probe or a small colloid that presents a uniform and known area could be better.
2. You want a spring constant that allows you to see the interaction of the probe, typically this may be around 0.1N/m but may vary depending on the end radius you end up using (i.e. a large colloid would give more adhesion than a sharp tip)
3. Practically, tip functionalization could be more or less involved depending on whether you have a silicon probe, silicon nitride probe, gold coated probe or colloid of some material. We have an excellent application note on this, if you have not seen it contact me offline and I can provide you a copy. There are also companies like "Novascan" that specialize in probe functionalization and as well as a whole host of standard offerings can make bespoke probes.
The idea of point and shoot is to take an image first and then use that image to navigate where you want to apply your force curves. If you do not require the AFM image you can always use the standard point spectroscopy GUI and just define an array of points (this obviously saves your functionalized probe from being dragged around the surface too much). Force volume is another good option.
Feel free to contact me at ian.armstrong@bruker.com for followup questions and if you need any documentation.
Best regards
Ian
We have several application notes that might be useful to you. I can send them to you if you can give me your email.
In addition, you can find several useful webinars that are related to your questions here. Please follow the link below to find out the webinars.
http://www.bruker.com/service/education-training/webinars/afm.html
Topics below should be useful to you:
"The AFM Probe - Fundamentals, Selection, and Applications"
"Nanomechanical AFM Measurements on Biological Samples"
"Best Practices in Imaging Biological Samples"
"Investigating Cell Mechanics with PeakForce QNM®"
Thanks,
Teddy