I am aware already of emulsion-based agents and certain polymer nanoparticle agents.
19F MRI requires a narrow line width to have decent resolution at low gradient bandwidth. The 19F nucleus must be in some regime of motional narrowing. Polymers are a good scaffold for this process, especially for per-fluoro methyl groups. The MRI characteristics of 19F ionic crystals or solids would experience a substantial dipolar broadening which would be poor resolved and low image intensity. 19F MRI great specificity but poor image signal-to-noise ratio because of the low concentration of 19F. In the MRI sphere, core groups using 19F are headed by Wickline or Ahrens. Currently there are 168 papers listed in the NIH National Library of Medicine PMC free full-text archive - you can find a broad introduction to the development and applications of 19F nanoparticles in MRI. See the following URL -
http://www.ncbi.nlm.nih.gov/pmc/?term=mri+nanoparticles+19f
Thank you for the link to the full-text archive - that's quite useful! I have read many Wickline and Ahrens papers already (I'd add Andrew Whittaker to the list), and I agree that achieving adequate conformational flexibility is a challenge. I have preliminary results that suggest that CF3 groups immobilized on nanoparticles can be seen by NMR with short (10 s) acquisitions. I'll keep searching the literature to see if anyone has done something similar. Thanks again for your help.
Andreas, thank you, I have read those papers. I'm guessing not much came of them, since she stopped publishing in this area. Cheers.
Dear Jeremy, my research group are submitting a couple of papers on this. Stay tuned :)
Can you tell me if they are polymer-based materials? Oh, I see you've done work with Wooley - an insider!
Jeremy - I'm not surprised that you have some interesting results from CF3 groups attached to your particles. The rotational symmetry acts to average the fields exposed to the group and also narrow the 19F resonance. Additionally, for very rapid exchange an additional relaxation term can be introduced "the spin-orbit" term which can short the longitudinal relaxation time. The utility of this in the extreme has been exploited by the use of perfluorinated gases for lung imaging with recycle times as little as 10 milliseconds.
Imaging obstructed ventilation with NMR using inert fluorinated gases - http://jap.physiology.org/content/88/6/2279.long
Nanoparticle 19F agents: http://www.ncbi.nlm.nih.gov/pubmed/20566214
These are polymer-encapsulated perfluorocarbon labels.
Thank you, Mangala, for passing on your paper. That is a very novel method you have developed. As far as you know, is yours the only report of other fluorine agents encapsulated in polymers?
I assume you mean non-lipid polymers? If so, then I don't know of any others. We published a review on 19F agents last year. Also in Biomaterials.
Yes, I meant non-lipids. I've downloaded your review (Thanks, ResearchGate), and I'll give it a closer look (though a brief glance confirms what you just told me). Thanks for your help!
Hi, Jeremy
I hope you have already known about PLGA PFOB by Elias Fattal. Here is the one (made by me) which was modified with Chitosan for cell labelling.
doi:10.1016/j.carbpol.2015.09.076
or modified with RGD for cancer targeting (by Odile Diou, 2014)
doi:10.1016/j.ejpb.2013.12.003
And one (also made by me) is in revision, so I will update when it is accepted.
I also have another fluorinated NP in manuscript preparation.
By the way, I am also looking for a postdoc position in 19F contrast agent and MRI. Please send me a message if you (one who are interested in 19F MRI) are looking for postdoc.
I can do the synthesis, 19F MRI and in vivo experiments. :)
You can check this paper...
Article Synthesis of a Fluorinated Graphene Oxide-Silica Nanohybrid:...
Hi, Andrea - thank you for the paper. Looks interesting. Take care!
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