The paper, “N, S co-doped graphene quantum dots from a single source precursor used for photodynamic cancer therapy under two-photon excitation,” was ostensibly written by nine researchers at the Collaborative Innovation Center for Marine Biomass Fiber, Materials and Textiles of Shandong Province, the Shandong Sino-Japanese Center for Collaborative Research of Carbon Nanomaterials, Laboratory of Fiber Materials and Modern Textiles, the Growing Base for State Key Laboratory at the College of Chemical Science and Engineering at Qingdao University, and Mayo Clinic, in Rochester, Minn.
According to the abstract:
Using polythiophene derivatives as single source precursors, nitrogen (N) and sulfur (S) co-doped graphene quantum dots (NS-GQD) were prepared. Under two-photon excitation (800 nm), the NS-GQD exhibited excellent photostability and high 1O2 generation, and therefore were developed as photodynamic therapy agents for cancer treatment.
But things fall apart. Here’s the notice (which is difficult to access, if not paywalled):
Xifeng Liu, Zonghua Wang, Feifei Zhang, Jianfei Xia, Min Yang, Sai Bi and Yanzhi Xia wish to resign as co-authors to the above article.
Xifeng Liu has declared that he contributed only to revision of the English language in the manuscript and did not participate in the experimental research reported. Zonghua Wang, Feifei Zhang, Jianfei Xia, Min Yang, Sai Bi and Yanzhi Xia declare that they did not participate in the experimental research that was reported in this article.
The corrected authorship list and affiliations for this paper are as follows:
Rijun Gui,*a and Hui Jin,a
(2) We, the named authors in the corrected authorship list, hereby wholly retract this Chemical Communications article due to data fabrication in the reported characterisation of the polycyclic aromatic hydrocarbon precursor (PTPD) and the realisation subsequent to publication that the reported values for the decomposition rate constant and the 1O2 quantum yield for the N, S co-doped graphene quantum dots (NS-GQD) are unreliable.
In Part S1 of the ESI the 1H-NMR data, 13C-NMR data, MALDI-TOF m/z data, and GPC data are copied from the data reported in ‘Copolythiophene-Derived Colorimetric and Fluorometric Sensor for Visually Supersensitive Determination of Lipopolysaccharide’, J. Am. Chem. Soc., 2012, 134, 6685–6694 for N,N-dimethyl-N′-(4-(thiophen-3-yl)benzyl)dodecan-1-aminium bromide (compound 4) and the corresponding homopolythiophene PT2. The 1H-NMR spectrum in Fig. S1b is copied from the 1H-NMR spectrum of compound 4 reported in Section 1.4 of the ESI of J. Am. Chem. Soc., 2012,134, 6685–6694.
We have been unable to reproduce the reported decomposition rate constant for ADPA with NS-GQD in subsequent experiments and therefore the reported rate constant cannot be relied upon. This was used in the calculation of the reported 1O2 quantum yield. Further to this we have discovered that the equation used to calculate the 1O2 quantum yield was incorrect and not the equation reported in Part S3 of the ESI. Therefore the reported 1O2 quantum yield of 1.26 used to support the conclusions of this paper is incorrect and the conclusions cannot be relied upon.
Signed: Rijun Gui and Hui Jin, 15th April 2015
Retraction endorsed by May Copsey, Executive Editor, Chemical Communications.
We emailed Gui for more information. Meanwhile, the journal tweeted this about the case:
— ChemComm (@ChemCommun) May 27, 2015
That has led to some interesting discussion.
Hat tip: Mark Chadders
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