A continuing war of words over “stripy nanoparticles” has reached new levels of acrimony following the appearance of a paper savaging data purporting to prove their existence.
The discovery of tiny particles of gold covered with stripes of other molecules called ligands was first reported in 2004 by Francesco Stellacci, now Constellium professor at the École Polytechnique Fédérale de Lausanne in Switzerland. He has since published about 30 papers on the subject.
However, as previously reported in Times Higher Education, in late 2012 Raphaël Lévy, a researcher in the University of Liverpool’s Institute of Integrative Biology, finally published – after three years of trying – a paper that dismissed evidence for their existence as an erroneous interpretation of microscopy data.
Under pressure from microscopy expert Philip Moriarty, professor of physics at the University of Nottingham, Professor Stellacci agreed to release his raw data, and asked three groups of researchers he characterised as “independent experts” to reproduce his work.
Their papers, which appeared in various publications in November, all concurred that Professor Stellacci’s data supported the existence of the particles.
However, in a new paper published on the physics pre-print server arXiv, Professor Moriarty, Dr Lévy and several others critique Professor Stellacci’s entire body of work on stripy nanoparticles and conclude that the evidence for the stripes amounts to what Professor Moriarty termed “a variety of other artefacts/noise, coupled with strong observer bias”.
“The most worrying aspect of this entire saga is that shockingly poor results and data analysis have made it through peer review so many times, to be published in what are regarded as some of the most prestigious scientific journals,” he said.
“This, coupled with the claims that the ‘stripiness’ can affect nanoparticle uptake by cells and may therefore have biomedical implications, makes this case a little bit more than just a ‘nano’ spat.”
But Professor Stellacci countered that the new paper, “Critical assessment of the evidence for striped nanoparticles”, contradicts Dr Lévy’s earlier arguments and includes factual errors. Conversations with Professor Stellacci’s colleagues indicated that they were sceptical of its arguments even before the forthcoming publication of Professor Stellacci’s response to the paper, which he said would “show how most of the arguments are wrong”.
The three groups that had confirmed his results – and with which he had “no ties” – had had their own analyses confirmed by a fourth group, he said.
“I have undergone the most rigorous process that a scientific process can take and there has been a consensus answer. This is undeniable,” he added.
He said he would send Professor Moriarty a sample of stripy nanoparticles when he had found further independent groups willing to analyse them.
“But I am really against this approach where we have a self-nominated king, whose images are the only ones that contain ‘the truth’, [especially] when the bias of this king is clear,” Professor Stellacci said.
“A year from the start of this story, and it is clearly apparent that this group will twist any data in front of them with the clear purpose of tarnishing my reputation.”