Writing for Physics World, the member magazine of the Institute of Physics, Jon Cartwright sums up the history and current state of the stripy nanoparticles controversy.
Here is one excerpt:
Stellacci himself was notably absent from the online discussions, but they did prompt him in October last year to publish work in collaboration with two independent groups led by Christoph Renner at the University of Geneva in Switzerland and Steven De Feyter at the University of Leuven in Belgium. The works, which were published in the journals ACS Nano (7 8529) and Langmuir (29 13723), sought to corroborate Stellacci’s original evidence with more advanced STM techniques. Unfortunately, they muddied the water even more: despite the images appearing almost stripe-free at first glance, the authors claimed that their analysis had indeed shown the stripe-like features to be present.
You can read the entire article here.
The above excerpt is particularly important if you consider this (unfortunately anonymous and therefore impossible to confirm) comment published at PubPeer:
As a reviewer of one of the recent papers, I asked specifically for the authors to address the discrepancy between the stripes so easily visible in the original paper and the stripes that I struggled to see in the present work. It’s disappointing that this wasn’t really addressed.
Rapha-z-lab 
What I don’t understand is that nobody questions the ‘independency’ of the groups that “confirmed” the stripy STM-images. In my opinion the two groups (by Renner and de Feyter) are not really independent. Renner is working at the university of Geneva and there are countless links between EPFL and the University of Geneva (which is normal, Switzerland is small, everybody knows each other).
I don’t know if there was a direct link between Stellacci and de Feyter before this story but I have an idea how they got together. And again, your buddies buddy isn’t really independent.
Sure, a lack of ‘independance’ doesn’t mean that you will be biased but it doesn’t help in this situation. There would have been many STM-experts all over the world who could have given a much more independent input.
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Perhaps I am misunderstanding something but I think the real problem is that neither Renner or de Feyter have made their positions clear on the validity of the 2004 images, I don’t think bias is an issue here, although their co-authorship is a sort of tacit endorsement of the stripy hypothesis. Their work clearly does *not* reproduce the results from 2004 (even though Stellacci has said almost exactly that), it would be a rather remarkable coincidence (though not impossible) that a conclusion derived from artefactual data is indeed true once correct imaging methods are applied.
I think everyone agrees that their STM work in the 2013 paper is high quality (I recall Phillip saying as much, I don’t have the expertise to evaluate). A shame they wouldn’t just come out and say either:
A)”You people have no idea what you are talking about, even though the 2004 images look very different our 2013 do validate them, this is clear to anyone with a basic knowledge of STM.”
B)”The 2004 images are spurious unfortunately, but we stand by our 2013 images and the stripy hypothesis presented there.”
This would narrow the scope of the debate considerably.
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@nanomymous; I completely agree that a few words from Renner and de Feyter would be of great help. It does not like this will happen though.
Meanwhile, there is one more ACS Nano paper on the effect of structural heterogeneity of nanoparticle surface on protein adsorption. Can’t check yet the SI, but there is no STM in the main ms. The existence of those particular stripy NPs (2:1 MUS:OT) is currently backed up by a grand total of one image of one nanoparticle (feedback artefact), yet it is the subject of no less than 5 papers. Pretty efficient use of instrumentation.
Given Paul Weiss expertise and the fact that ACS Nano has now published several recent stripy papers, I think we could ask this prominent journal to do something big that would definitely solve the controversy: organize a real independent study of the stripy nanoparticles. If Paul was to invite a number of groups to do their own study and come to their own conclusion, with samples provided by Francesco, with publication in ACS Nano, that would be a great service to the community.
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Paul’s quote in the CEN article seems to suggest he does not believe the 2004 findings were conclusive:
“The early data were inconclusive,”
I really feel that it is important to note for non-specialists:
I think it is a fair assumption in general, across essentially every field of scientific imaging, we generally don’t look back at imaging and lightly suggest that it was not conclusive, the point of the 2004 paper was that there were conclusively stripes at a specific spatial scale proven by images. If the conclusions did not line up with the images a very careful explanation is in order.
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If the stripies are not really striped, will the protein/membrane/catalyst/majikpowder applications also be found to be artifacts? Or do we feel confident that A/B mixed ligand NPs (or even mixes of A and B ligand NPs) show a higher chemical response than all A or all B coated NP? How good does the application paper stuff look? Drago?
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