Forums
Bruker Media
Community Media
Bruker AFM Probes
SPM Digest
Application Notes
NanoTheater
Website
中文
Brochures & Datasheets
Publications
Probes Catalog
Events
Manuals & Documentation
Presentations
Guide to AFM Modes
News
Journal Club
Webinars & Video
Nanovations
Other
Dear All
I've worked now for some time with PFQNM and functionalised NPG-10 Au coated probes, using SAMs such as mercapto-alkyl-carboxyl/hydroxyl/hydroquinone/diquinone on a lignin-nanocellulose (polyphenol/polyglucose) system in buffer liquid to see if I could topochemically characterise the two elements. Unfortunately, it has only rarely payed off, i.e. only on very few occasions have I experienced the hydrophobically functionalised probes adhere stronger to the lignin part than to the cellulosic part.
It seems, no matter what hydrophobic SAM I use, the probe adheres strongest to cellulose. Important to note is that the cellulose also constitutes the topographically lower areas as the lignin has been placed as droplets onto the nanocellulose surfaces, then dried in an oven to make it 'melt' and better stick to the cellulose in buffer solution. Thus, the lignin, in this system, represents relatively higher areas compared to the cellulose and no matter if I use a functionalised probe complementary to lignin, or an unfunctionalised DNP probe for example, I always see relatively higher adhesion to the cellulose.
Upon IR analysis of my Au-coated probes, after having 'soaked' in 1 mM solution of either hydroquinone or diquinone dissolved in either EtOH or toluen for 24 hours, I don't see any bands proving that my probes have actually been functionalised. That would of course explain why I don't see any strong adhesion between my quinone-functionalised probes and the lignin, yet according to the literature I don't seem to be doing anything wrong.
Have any of you had similar issues...?
Best regards
Mads
Hi Mads,
Before we go deeper into the discussion, I have 2 questions:
1) what type of probe (especially spring constant) did you use?
2) before trying with PF, did you try in regular force volume?
Greets,
Alex.
Hi Alex
Thanks for taking interest in my problem. The answers to your questions are:
1) npg-10 Au coated probes - usually the B cantilever, spring constant ~0.25 N/m after functionalisation as measured on a sapphire surface in buffer solution.
2) no, I was, I'm sorry to say, not aware that the multimode AFM I use for PFQNM had a Force Volume feature (I assume the feature includes what is described below):
file:///C:/Program%20Files/Nanoscope/VeecoDataAnalysis/Help/Default_Left.htm#CSHID=2|StartTopic=Content%2F2D_Image.htm|SkinName=VeecoSkin
... so far only I've tried using QNM in fluid and also PeakForce, where the latter supposedly gives the me single force curves I expect I need to extrapolate afterwards using MatLab. Additionally, I've tried, only briefly though, to do CFM using a DI3100 (also NanoScope IIIa controller) in friction mode (LFM).
My best regards
1) This sounds a bit stiff. I would rather go below 0.1 N/m.
2) Yes it does. And as PFT is really at the beginning with respect to measurements with tip functionalization I would rather test your probes and samples with Force volume. Also, as you mentioned LFM is another very good option (even simpler than Force Volume) to test how well your pobe is tagged.
I think the protocols you mentioned in the last post are very good. I don't see anything that can be improved...
Did you try (after intensive rinsing) to analyse your probe by XPS?
Anyway, as long as you are ready to start with PFT or PFQNM, I am all for keeping an eye on your progresses. Please keep me infomed.
Good luck,