Integrity Review Report: Green Synthesis of Nitrogen-Doped Carbon Dots from Fresh Tea Leaves for Selective Fe³⁺ Ions Detection and Cellular Imaging

Academic fraud report · Geng Detector

Summary

Verdict: Questionable (yellow). The paper by Ge et al., published in Nanomaterials (MDPI, 2022; DOI 10.3390/nano12060986), shows several visual and methodological irregularities that fall short of definitive fraud but warrant author clarification. Key issues include an unusually clean linear fit in Figure 5C (R²=0.9948 across 0.1–400 μM, ~12 points), error bars of near-uniform length in Figures 5D and 6, missing TEM particle-count statistics (only a mean diameter of 2.32 nm reported, no SD or N), incomplete CCK-8 reporting (no replicate or repeat counts), and a 31-day submission-to-publication cycle. Programmed image-forensic signals (PRNU NCC=1.000, copy-move, noise CV=1.31) cited by automated tools could not be verified against source pixels. Confidence is moderate; uncertainty is high because benign explanations (stable instrumentation, narrow linear range, identical replicates) cannot be ruled out without raw data. Authors should be asked to release underlying spectra, OD readings, and particle measurements.

Verdict

🟡 Questionable — multiple visual and reporting irregularities are present, but no single finding is independently sufficient to confirm misconduct. Raw data from the authors is required for a definitive assessment.

Key findings

Figure 5C (linear calibration, 0.1–400 μM, R²=0.9948): ~12 data points sit almost perfectly on the fitted line, lacking the random scatter typical of real fluorescence measurements. Concentration list in 5B spans 0–1000 μM (0, 0.1, 1, 10, 25, 50, 100, 150, 200, 250, 400, 500, 750, 1000 μM), only weakly matching the 0.1–400 μM range used in 5C.
Figure 5D (metal-ion selectivity): Error bars across ions appear unusually similar in length; independent triplicates would not normally produce near-identical dispersion.
Figure 6 (CCK-8, A549 viability, 0–400 μg·mL⁻¹): All six bars remain above 85%, and error bar caps look uniformly tight. The figure caption states only "Untreated cells served as the control… set as 100%," with no replicate count or independent repeat number declared in Section 2.6.
TEM particle sizing (Figure 1B): Only a single mean of 2.32 nm is reported; no standard deviation and no count N are given. Conventional TEM size analysis requires ≥100 particles.
Submission-to-publication timeline: Received 14 February 2022 → Accepted 3 March 2022 → Published 17 March 2022 (31 days). This is within MDPI's normal rapid-publication range and is not, on its own, a fraud signal.
Programmed forensic indicators (PRNU NCC=1.000, copy-move detection, noise-variance CV=1.31): These automated outputs could not be cross-checked against source pixel data and were therefore excluded as primary evidence.

Evidence highlights

DOI: 10.3390/nano12060986
R² reported for Figure 5C: 0.9948; linear range stated as 0.1–400 μM
Concentration series listed in Figure 5B: 0, 0.1, 1, 10, 25, 50, 100, 150, 200, 250, 400, 500, 750, 1000 μM
Average TEM diameter (Figure 1B): 2.32 nm (no SD, no N)
CCK-8 concentrations in Section 2.6: 0, 25, 50, 100, 200, 400 μg·mL⁻¹; viability stated as "above 85%"
Dates: Received 14 February 2022; Accepted 3 March 2022; Published 17 March 2022

Notes

All visual anomalies have plausible benign explanations (instrument stability, log-scale compression, narrow concentration range, uniform assay conditions), but the manuscript provides no methodological text supporting these.
Automated forensic metrics cited by upstream tools (MAD=0.0407, χ²=612.5, NCC=1.000, PCE=128.0, CV=1.31, 0/993 anomalous blocks) are not retrievable from the published text or figures and therefore could not be independently verified; they are not used as load-bearing evidence here.
Recommended next step: post a PubPeer comment requesting (i) raw fluorescence intensities for Figure 5C, (ii) F/F₀ replicates for Figure 5D, (iii) raw OD values, replicate count and independent repeats for Figure 6, and (iv) ≥100-particle diameter measurements with N and SD for Figure 1B. If the authors cannot supply these, escalate to the Nanomaterials editorial office before any institutional complaint.
Limitations: this review relied on the published PDF and an accompanying AI-generated visual summary; original TIFF/RAW images were not available for pixel-level forensic re-analysis.