Nanostripe controversy in new twist

Simon Hadlington, writing for Chemistry World, reports on our new paper:

A simmering controversy over whether certain nanoparticle structures are merely instrument artefacts has boiled over into a bitter dispute, with a senior scientist alleging that he has become the victim of a personal vendetta, something that is strongly denied by researchers on the other side of the argument.

A significant section of the report deals with such accusations. These are not new. More interestingly, given the very small number of scientists who have expressed a public view on the controversy, it was notable to read the following from Paolo Samori, from the University of Strasbourg:

In my laboratory we have imaged Professor Stellacci’s particles and found that these particles indeed have stripes on them. The images show clear features that are invariant with imaging parameters (scan rate, scan angle, feedback loop, etc) and hence they can ascribe to true tip sample interactions […] (he then goes to discuss power spectral analysis, this is thoroughly address in Stirling et al, e.g. see fig 10)

I would like to invite Prof Samori to share these images “that indeed have stripes on them”, e.g. using FigShare. In the meantime, we can only relie on the published evidence. To my knowledge, the only image of stripy (?) nanoparticles published coming from Samori’s lab is from Biscarini et al and is reproduced below next to stripy nanoparticles from the original 2004 Jackson et al paper.

left from Fig 1a of Jackson et al (2004), right from Biscarini et al (2013)

left from Fig 1a of Jackson et al (2004), right from Biscarini et al (2013), fig 1d

Reactions to this 2013 Biscarini et al were somewhat incredulous:

Mathias Brust: “And yet there are stripes

Quanmin Guo: “Where are the stripes

Philip Moriarty: “The Emperor’s new stripes

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7 comments

  1. Stellacci does not acknowledge that it isn’t just Stirling et al.

    The detailed and (presumably) impartial and independent referee reports agree with Stirling et al. Paul Weiss does as well:

    “The early data were inconclusive,” [referring to the 2004 image]
    http://cen.acs.org/articles/92/i21/Big-Tussle-Over-Tiny-Particles.html

    Other anonymous commentators and at least a few other blogs also agree*.

    It is possible that all the above people are wrong, but one needs to provide a compelling explanation. Malice as an explanation doesn’t align the the tone of Stirling et al.’s criticism.
    The infamous “Unreg” on Pubpeer, Paimes and Samori have not provided arguments that are compelling. Between the 2004 image and arguments associated with other Stellacci papers (e.g. the spurious invocation of the “harry ball theorem” ), I am sincerely concerned about the validity of the entire body of work. I sincerely encourage Samori to post some images and required data. There is no need to wait for peer review to finish, just post some images and data and discuss in good faith just as you would do within your labs.

    I’ve made the analogy many times, but there are a number of people who were involved in the “#arseniclife” saga who (as far as I know) defend the claims of that paper with vague and nebulous reasoning. The paper is clearly wrong (in an elementary sense), and I’m sure that the explanation for their behavior is rooted in sociology and psychology, not deductive reasoning. I do not mean this as an insult, but the parallels to stripy nanoparticles is becoming more and more clear.

    * Worth noting that there has been a surprising silence from STM specialists who, for some reason, are not willing to provide opinions and analysis.

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  2. Surprising that the comments from several of S. et al.’s co-authors has been along the lines of: “We have insurmountable evidence from our labs (not shown here) that the stripes exist.”.

    If you do, is that not what you were supposed to include in the publications? There have been 30 papers-worth of opportunities to show them! As the situation stands, the line above should be followed by a “You have to believe me!”.

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  3. Just wanted to agree with your comment on Gkeka et al.:

    “The increasing applications of nanotechnology in medicine rely on the fact that engineered nanomaterials, such as diagnostic and therapeutic nanoparticles, are able to translocate across the cellular membrane and reach their site of action without toxic effects.”

    Like you said, I don’t think there is a fundamental disagreement with the authors, but the they should at least qualify this assertion with the fact that (to date) there are no diagnostic or therapeutic nanoparticles (in the “gold nanoparticle” sense of the word being used here…).

    There is a lot of work and papers that are working on things from this perspective, but the abstracts for such papers tend to qualify with the word “potential”.

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  4. Wei Chen of SINANO (http://sourcedb.sinano.cas.cn/yw/peo/facultyorstaff/201005/t20100518_2847745.html) appears to have commented on the PLOS comments page. I’m glad Wei has decided to comment, and I’d like to respond to his post here.

    ” However, when analyzing images for scanning artifacts they only analyze 1 image (Figure-1) out of many tens that have been published.”

    I presume the authors focus on that image to make it easier to communicate a cogent argument that outlines the fundamental concerns about Stellacci’s body of work. Wei (carefully) does not appear to state his position on the *validity* of the 2004 image, which is the crux of the matter. By not stating his position, Wei is implying that Stirling et al.’s analysis is valid for this image but if they only looked at all their other data they would find mounds and mounds of valid images. Once one decides on a position regarding the validity of the specific image, they can move forward and assess the validity of the remaining body of work.

    There is an obvious reason the authors focus their artifact analysis on this image Wei. That image is the one that announced that “stripy” phenomenon (with rather pronounced “stripes” that have never been replicated, you surely must agree with this Wei, there is no other image that looks like that centerpiece of the 2004 paper). The image was so “good “it was used 4 years later in PNAS in 2008 (https://raphazlab.wordpress.com/2013/03/22/five-cases-of-data-re-use/). Wei, it behooves you to select additional images and provide some explanation as to how one would go about assessing validity (you seem to already believe there are no other problems with validity, how do you know?).

    ” [the fact that feedback can produce convincing “stripes”] … does not mean that stripes cannot arise from physically reasonable arguments rather than imaging artifacts. ”

    Stirling et al. have made this point again and again and again and again and again and again. I was disappointed that you did not acknowledge this in your comment, especially since you cite pubpeer and must be familiar with the online discussion so far.

    “The problem with Figure-4 is that Stirling et al assumed that features in the images analyzed in Figure-4 all come from feedback ringing without saying so in the paper !”

    Stirling et al. providing a very simple explanation for otherwise quite magical stripes, their explanation is compelling. Since you cite the “Gustav” thread in the comments section, can you point to a reference in STM where authors corrected for (very) local background estimation and resolved features that would otherwise be lost?

    “In Figure-5 Stirling et al show that arithmetic addition of a sets of published trace and retrace images of same area showing stripes leads to particles without stripes. This has also been criticized before in pubpeer — for summation procedure to work, resolution of the images has to be good enough, which is not the case in Figure-5. ”

    This is a basic principle of scientific imaging across essentially any field. Perhaps best to stop here and see if Wei would consider commenting here on at least the first point (which is critical). Wei, do you believe the image that Stirling et al. focus their artifact analysis on is in fact an accurate STM image of a “striped” nanoparticle? Do you believe that the image is reproducible with valid STM image acquisition technique (i.e. the extremely prominent “stripes”)? Why can we not see another image in Stellacci’s work where the same obvious “stripes” are visible?

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    1. *Thank you*, Nanonymous, for that v. helpful comment. I particularly liked this:

      “Stirling et al. have made this point again and again and again and again and again and again.”

      We have. We have indeed.

      Philip

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