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REVIEW 3 major objections 4 minor 48 references

Single-molecule Surface-Induced Fluorescence Attenuation Based on Reduced Graphene Oxide

T0 review · 3 major / 4 minor · reviewed 2026-08-11 · deepseek-v4-flash

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Pith's one-line read Thermally reduced graphene oxide tunes the characteristic quenching distance d0 of surface-induced fluorescence attenuation from about 4 nm (GO) to 6.3 ± 0.5 nm (300°C-2h-rGO) and 7.9 ± 0.5 nm (400°C-2h-rGO), and the 400°C material…

desk verdict Thermal reduction tunes rGO's SIFA quenching distance; the absolute d0 values are provisional but the method and demonstration are solid enough for peer review. read the letter →

arxiv 2412.19592 v1 pith:MXOG47UZ submitted 2024-12-27 physics.bio-ph

Q. Fan , C. Yang , S. Hu , C. Xu , M. Li , Y. Lu This is my paper · ORCID
classification physics.bio-ph PACS 78.67.Wj82.80.Pv87.14.gk87.15.H
keywords reducedgrapheneoxidesurface-inducedfluorescenceattenuationcharacteristicquenchingdistanceresonanceenergytransfersingle-moleculeimagingHollidayjunctionthermalreduction
verification ladder T0 review T1 audit T2 compute T3 formal

The pith

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

The reading

Single-molecule surface-induced fluorescence attenuation (smSIFA) measures a dye's height above a two-dimensional material by how much the material quenches its fluorescence; the problem is that each material has a fixed detection window. This paper sets out to make the window tunable by using thermally reduced graphene oxide (rGO) as the acceptor. Because baking removes oxygen groups, the reduction temperature continuously adjusts the characteristic quenching distance d0, and DNA-ruler measurements give d0 = 6.3 ± 0.5 nm at 300°C and 7.9 ± 0.5 nm at 400°C. The payoff is shown on a DNA Holliday junction: the 400°C material resolves its two conformational states, while graphene oxide, with d0 ≈ 4 nm, cannot. A tunable d0 would let one material system cover a wide range of membrane-protein heights instead of forcing a material swap.

What carries the argument

The central object is thermally reduced graphene oxide (rGO), produced by baking a single-layer GO film on a coverslip in a vacuum tube furnace; the reduction temperature sets the degree of reduction, which in turn sets the characteristic quenching distance d0 in the SIFA equation E = 1 − I/I0 = 1/(1 + (d/d0)^4). The calibration machinery consists of Cy3-labelled double-stranded DNA rulers at the 1st, 9th, and 21st base pairs, combined with a geometric model in which the DNA is a rigid rod tilted 60° from the surface normal, with a 3 nm BSA layer and a 4.2 nm streptavidin layer underneath and a 0.34 nm rise per base pair. The argument's driving assumption is that the reduction temperature controls d0 monotonically, placing the Holliday junction's two vertical states in the sensitive region of the attenuation curve.

What would settle it

Repeat the d0 calibration on the same rGO batches using an independent height standard—for example DNA rulers of different lengths whose expected heights are checked by atomic force microscopy—and see whether the inferred heights agree with the 60°-tilt model; or bake rGO at intermediate temperatures such as 250°C and 350°C and test whether d0 falls monotonically between 6.3 nm and 7.9 nm as the tuning claim requires.

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Extended reading notes

Core claim

The central claim is that the characteristic quenching distance d0—the height at which fluorescence is attenuated by half—is a controllable material property, not a fixed one. The authors bake Langmuir–Blodgett monolayers of graphene oxide in a vacuum furnace at 300°C or 400°C for two hours, producing rGO with C/O ratios of 2.48 and 3.29 (vs. 1.14 for GO), and show that the quenching strength increases with reduction. Using Cy3-labelled double-stranded DNA rulers attached through biotin–BSA–streptavidin, they measure intensity ratios of 0.66 I0 and 0.45 I0 at the 1st base pair on the two rGO surfaces, which convert to d0 = 6.3 ± 0.5 nm (300°C-2h-rGO) and 7.9 ± 0.5 nm (400°C-2h-rGO) through the SIFA relation E = 1/(1 + (d/d0)^4). In the key demonstration, a Cy3-labelled Holliday junction on 400°C-2h-rGO shows two intensity states, 0.42 I0 and 0.83 I0, corresponding to vertical distances of 7.3 nm and 11.7 nm—matching the expected 7.5 nm and 11.1 nm—whereas the same junction on graphene oxide shows no resolvable intensity change. The paper concludes that thermally reduced rGO extends and tunes the measurable vertical range of single-molecule SIFA and is ready for membrane-protein studies.

Load-bearing premise

The d0 values depend on a geometric model in which the DNA ruler stands at a fixed 60° angle to the surface normal with 3 nm BSA and 4.2 nm streptavidin layers underneath; if the true angle or protein dimensions differ, every d0 and every inferred Holliday-junction distance shifts.

Editorial extensions

If this is right

  • Researchers can choose a baking temperature to match d0 to the size of the molecule, continuously covering the range from ~4 nm (GO) to 7.9 nm (400°C-2h-rGO), and potentially further with quartz coverslips.
  • The 400°C-2h-rGO surface detects conformational transitions of a DNA Holliday junction that are invisible on graphene oxide, because its larger d0 brings the junction's ~7.5 nm and ~11.1 nm states into the instrument's sensitive window.
  • Because rGO emits no fluorescence of its own, the improved sensing range does not come at the cost of signal-to-noise ratio in single-molecule imaging.
  • Combining rGO-SIFA with single-molecule FRET should allow simultaneous readout of vertical and lateral motion, enabling three-dimensional tracking of membrane proteins in real time.

Reading between the lines

Editorial extensions of the paper, not claims the author makes directly.

  • The monotonic link between baking temperature and d0 is only tested at two temperatures; a natural extension is to measure d0 at a grid of temperatures (e.g., 250°C, 350°C) to map the tuning curve and find where the response saturates.
  • The same thermal-tuning principle could apply to other two-dimensional acceptors or to patterned rGO regions on one coverslip, allowing a single experiment to multiplex several calibrated height windows.
  • The paper's geometric model assumes a single tilt angle for all surface-attached DNA; if tilt were distributed, the quoted d0 values would be effective averages, and polarization-resolved or length-dependent measurements could reveal that spread.
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Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, and a circularity audit.

Referee Report

3 major / 4 minor

Summary. The paper reports a single-molecule surface-induced fluorescence attenuation (smSIFA) method in which the acceptor material is thermally reduced graphene oxide (rGO). By baking graphene oxide at 300°C and 400°C, the authors obtain rGO with different reduction degrees, as confirmed by XPS C/O ratios (1.14, 2.48, 3.29). Using biotinylated double-stranded DNA labeled with Cy3 at three positions, they measure the fluorescence attenuation on rGO and, via Eq. (1), extract characteristic quenching distances d0 = 6.3 ± 0.5 nm (300°C) and d0 = 7.9 ± 0.5 nm (400°C). They then apply the 400°C-rGO to a DNA Holliday junction and observe two intensity levels, which they interpret as two conformational states at distances 7.3 nm and 11.7 nm. They argue this demonstrates a tunable detection window between GO (d0 ≈ 4 nm) and graphene (d0 ≈ 18 nm), and that rGO can resolve vertical motions that GO cannot.

Significance. If the quantitative calibration is reliable, the paper provides a practical, tunable acceptor material for single-molecule vertical-distance measurements, filling a gap between GO and graphene. The XPS characterization is convincing, and the internal consistency of d0 derived from three DNA labeling positions is a genuine strength: it supports the relative spacing of the DNA ruler and the validity of Eq. (1) for rGO at these distances. The observation of two intensity levels for the Holliday junction is also a useful proof-of-principle. However, the absolute distance scale rests on unverified geometric assumptions, and the Holliday-junction 'confirmation' is partially circular. These issues do not invalidate the qualitative tunability claim, but they do limit the precision of the stated d0 values.

major comments (3)
  1. [Section 3.2, Table 1] The absolute d0 values depend on the assumed geometry h = t_BSA + t_SA + n×0.34 nm×cos(60°), with t_BSA = 3 nm, t_SA = 4.2 nm, and a 60° DNA tilt angle, none of which are measured in this work. A uniform offset in the assumed BSA/SA thickness or binding height is not detectable by the cross-label consistency check: for example, reducing the base height by 1 nm shifts the 400°C d0 from ~7.9 nm to ~6.8 nm, while the three positions still appear mutually consistent. The reported uncertainties (±0.5 nm) propagate only intensity measurement noise, not model uncertainty. Please provide a sensitivity analysis over the plausible ranges of these parameters, or validate the geometry with an independent method (e.g., AFM height measurements, or a DNA ruler of a different persistence-length regime).
  2. [Section 3.3] The Holliday junction demonstration is not an independent validation of the absolute distance scale. Both the d0 calibration and the Holliday-junction analysis use Eq. (1) and the same assumed DNA height model; the 'theoretical' distances of 7.5 nm and 11.1 nm are computed with the same 3 nm BSA + 4.2 nm SA + 60° tilt assumptions. The agreement between the inferred distances (7.3 nm and 11.7 nm) and these theoretical values is therefore partly built in. The observation of two resolvable intensity levels does confirm that the junction undergoes a vertical conformational change, but it does not independently confirm the absolute d0 values. Please state this limitation explicitly, or provide a cross-check that does not rely on the same calibration (e.g., a junction with different arm lengths, or using two rGO samples with independently known d0).
  3. [Eq. (1) and Section 3.2] The paper assumes the GO-derived quenching law E = 1/(1 + (d/d0)^4) applies unchanged to rGO. No experimental test of the functional form is provided for rGO; a different power-law or a non-power-law distance dependence would change all extracted d0 values and the Holliday-junction distances. If a validation is not feasible, the model dependence should be acknowledged as a source of systematic uncertainty in the stated d0 values.
minor comments (4)
  1. [Section 3.2, sentence before Table 1] "The residence length of double-stranded DNA in solution is 50 nm" should read "persistence length"; reference [36] is a measurement of DNA persistence length, not residence length.
  2. [Abstract and Introduction] "Single-molecular" appears in the abstract and title; the standard term in the field is "single-molecule".
  3. [Section 3.3, Fig. 4] The Holliday-junction intensity peaks are reported as 0.42 I0 and 0.83 I0; the corresponding distances 7.3 nm and 11.7 nm use d0 = 7.9 nm. It would be helpful to show the error bars on these peak values and to discuss how the intensity histogram peak fitting was performed.
  4. [Conclusion] The claim that d0 can be "continuously tuned from 4 nm to 7.9 nm" is based on only two measured rGO temperatures plus literature GO; the intermediate temperatures are not demonstrated. This should be phrased as a projection, not a demonstrated property.

Circularity Check

0 steps flagged · score 0.0 of 10

No circular derivation: d0 is calibrated with DNA rulers and then applied to independent Holliday junction intensity data; the Holliday junction agreement shares the same geometric model but is not used to define d0.

full rationale

The paper's derivation chain is not circular. The characteristic quenching distance d0 is determined from fluorescence intensities of Cy3-labeled double-stranded DNA at three known positions (1 bp, 9 bp, 21 bp) using Eq. (1), with absolute heights taken from literature values for BSA thickness, streptavidin thickness, and the 60° attachment angle. These are external geometric inputs, not quantities derived from the Holliday junction data. The Holliday junction experiment then uses the already-calibrated d0 value to convert measured intensity ratios into distances; this is a standard application of a calibrated relation, not a self-referential prediction. No Holliday junction data are used to fit d0, and no parameter is defined in terms of the later measurement. The observed agreement between the Holliday junction distances (7.3 nm and 11.7 nm) and the model-based values (7.5 nm and 11.1 nm) is a consistency check that shares the same geometric assumptions, so it does not independently validate the absolute height scale. That is a limitation in external anchoring, not circularity. The central claim of tunable d0 with reduction temperature is supported by XPS reduction data and by independent intensity measurements at different labeling positions. Self-citations to prior SIFA work, including the origin of Eq. (1), provide an externally published empirical foundation rather than an unverified assumption whose content is equivalent to the present result. Therefore, no circular step can be exhibited and the score is 0.

Assumptions & free parameters 0 free parameters · 4 assumptions · 0 invented entities

The central measurement is the d0 value, which is directly propagated from intensity ratios and assumed molecular geometry; the geometry constants are prior-literature inputs rather than parameters fitted in this paper. The main unverified inputs are the tilt angle and protein sizes, plus the validity of Eq. (1) for rGO.

assumptions (4)
  • domain assumption SIFA follows E = 1/(1 + (d/d0)^4) on reduced graphene oxide.
    Adopted from ref [11] without re-derivation; the exponent 4 is not independently validated for rGO in this work.
  • domain assumption Double-stranded DNA acts as a rigid rod tilted at a fixed 60° angle from the surface normal.
    Based on refs [38,39]; uncertainty in tilt angle directly shifts all inferred heights and thus d0.
  • domain assumption The biotin-BSA and streptavidin layers have heights of 3 nm and 4.2 nm respectively.
    Literature values [40,41] used to assign absolute dye heights; variation in these dimensions would systematically move d0.
  • domain assumption Reduction degree increases monotonically with baking temperature, allowing continuous d0 tuning.
    Supported by XPS C/O ratios at two temperatures, but continuous tunability from 4 to 7.9 nm is extrapolated from only two points.

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Cite this review

Pith. "Pith review of Single-molecule Surface-Induced Fluorescence Attenuation Based on Reduced Graphene Oxide." pith.science (2026). https://pith.science/paper/MXOG47UZ

@misc{pith2026241219592,
  author       = {Pith},
  title        = {Pith review of: Single-molecule Surface-Induced Fluorescence Attenuation Based on Reduced Graphene Oxide},
  year         = {2026},
  howpublished = {\url{https://pith.science/paper/MXOG47UZ}},
  note         = {Machine review of arXiv:2412.19592}
}
read the original abstract

Single-molecule surface-induced fluorescence attenuation (smSIFA) is a precise method for studying the vertical movement of biological macromolecules using two-dimensional material acceptors. Unlike other methods, smSIFA is not influenced by the planar motion of membranes or proteins. However, the detection range and accuracy of vertical movement are dependent on the properties of these two-dimensional materials. Recently, smSIFA utilizing graphene oxide and graphene has significantly advanced the study of biomacromolecules, although the detection range is restricted by their inherent quenching distances. Modifying these distances necessitates the replacement of the medium material, which presents challenges in material selection and preparation. Consequently, there is a pressing need to develop controllable materials for smSIFA applications. In this study, we enhance the smSIFA technique using graphene oxide as the medium acceptor through thermal reduction. By adjusting the reduction temperature, we prepare reduced graphene oxides at varying degrees of reduction, thus fine-tuning the quenching distances. The adjustment of these distances is measured using fluorescently labeled DNA. This modified smSIFA approach, employing reduced graphene oxide, is then applied to observe conformational changes in the Holliday junction, demonstrating the enhanced detection capabilities of reduced graphene oxide.

Figures

Figures reproduced from arXiv: 2412.19592 by the authors.

Figure 1
Figure 1. Fig.1. SIFA method of regulatable [PITH_FULL_IMAGE:figures/full_fig_p003_1.png] view at source ↗
Figure 2
Figure 2. XPS spectra of the original GO and rGO films. (a) c1s XPS spectra (left) and XPS survey [PITH_FULL_IMAGE:figures/full_fig_p006_2.png] view at source ↗
Figure 3
Figure 3. Determination of d0 of rGO by fluorescence labeled DNA. (a) Schematic representation of DNA imaging; (b) DNA imaging on 300℃-2h rGO (upper) and 400℃-2h rGO (lower); (c-e) Intensities of cy3 labeled at 1bp (c)、9 bp (d)、21bp (e) of DNA on glass and rGO. There is a difference in the lower intensity of Cy3 in the 300°C-2h-rGO and 400°C-2h-rGO sample chambers, which are 0.66I0 and 0.45I0, respectively, indicating that th… view at source ↗
Figures from the paper (1 more)
Figure 4
Figure 4. Figure 4: Observing the conformational transition of Holliday junction by SIFA. (a-c) Observing the Cy3 labeled Holliday junction on glass (a)、GO (b)、400℃-2h rGO (c), left columns show intensity￾time curves of a single Cy3, middle columns show distribution of intensities of Cy3,…

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Works this paper leans on

48 extracted references · 48 canonical work pages

  1. [1]

    2021 Elife 10 e60416

    Lerner E, Barth A, Hendrix J, et al. 2021 Elife 10 e60416

    work page 2021

  2. [2]

    Keller A M, DeVore M S, Stich D G, Vu D M, Causgrove T, Werner J H 2018 Anal. Chem. 90 6109

    work page 2018

  3. [3]

    Ishikawa-Ankerhold H C, Ankerhold R, Drummen G P 2012 Molecules 17 4047

    work page 2012

  4. [4]

    Jia Q, Fan Q K, Hou W Q, Yang C G, Wang L B, Wang H, Xu C H, Li M, Lu Y 2021 Acta Phys. Sin. 70 158701 (in Chinese)

    work page 2021

  5. [5]

    Almen M S, Nordstrom K J V , Fredriksson R, Schioth H B 2009 Bmc. Biology. 7 50

    work page 2009

  6. [6]

    White S H, Wimley W C 1999 Annu. Rev. Bioph. Biom. 28 319

    work page 1999

  7. [7]

    Ma D F, Hou W Q, Xu C H, Zhao C Y , Ma J B, Huang X Y , Jia Q, Ma L, Liu C, Li M, Lu Y 2020 Acta Phys. Sin. 69 038701 (in Chinese)

    work page 2020

  8. [8]

    Ponmalar, II, Cheerla R, Ayappa K G, Basu J K 2019 Proc. Natl. Acad. Sci. USA 116 12839

    work page 2019

Show all 48 references
  1. [9]

    King C, Raicu V , Hristova K 2017 J. Biol. Chem. 292 5291

    2017

  2. [10]

    King C, Sarabipour S, Byrne P, Leahy D J, Hristova K 2014 Biophys. J. 106 1309

    2014

  3. [11]

    Li Y , Qian Z, Ma L, Hu S, Nong D, Xu C, Ye F, Lu Y , Wei G, Li M 2016 Nat. Commun. 7 12906

    2016

  4. [12]

    Ma L, Li Y , Ma J B, Hu S X, Li M 2018 Biochemistry 57 4735

    2018

  5. [13]

    Jiang X, Yang C G, Qiu J, Ma D F, Xu C, Hu S X, Han W J, Y uan B, Lu Y 2022 Nanoscale 14 17654

    2022

  6. [14]

    Ma L, Hu S X, He X L, Yang N, Chen L C, Yang C G, Ye F F, Wei T T, Li M 2019 Nano. Lett. 19 6937

    2019

  7. [15]

    Kaminska I, Bohlen J, Yaadav R, Schuler P, Raab M, 2021 Adv. Mater. 33 e2101099

    2021

  8. [16]

    Kaminska I, Bohlen J, Rocchetti S, Selbach F, Acuna G P, Tinnefeld P 2019 Nano. Lett. 19 4257

    2019

  9. [17]

    Federspiel F, Froehlicher G, Nasilowski M, Pedetti S, Mahmood A, Doudin B, Park S, Lee J O, Halley D, Dubertret B, Gilliot P, Berciaud S 2015 Nano. Lett. 15 1252

    2015

  10. [18]

    Gaudreau L, Tielrooij K J, Prawiroatmodjo G E D K, Osmond J, de Abajo F J G, Koppens F H L 2013 Nano. Lett. 13 2030

    2013

  11. [19]

    Li W, Wojcik M, Xu K 2019 Nano. Lett. 19 983

    2019

  12. [20]

    Nanotechnol

    Eda G, Fanchini G, Chhowalla M 2008 Nat. Nanotechnol. 3 270

    2008

  13. [21]

    Pei S F, Cheng H M 2012 Carbon 50 3210

    2012

  14. [22]

    Stankovich S, Dikin D A, Piner R D, Kohlhaas K A, Kleinhammes A, Jia Y , Wu Y , Nguyen S T, Ruoff R S 2007 Carbon 45 1558

    2007

  15. [23]

    Sulowska K, Wiwatowski K, Szustakiewicz P, Grzelak J, Lewandowski W, Mackowski S 2018 Materials (Basel) 11 1567

    2018

  16. [24]

    Kim J, Cote L J, Kim F, Huang J X 2010 J. Am. Chem. Soc. 132 260

    2010

  17. [25]

    Kovtyukhova N I, Ollivier P J, Martin B R, Mallouk T E, Chizhik S A, Buzaneva E V , Gorchinskiy A D 1999 Chem. Mater. 11 771

    1999

  18. [26]

    Hummers W S, Offeman R E 1958 J. Am. Chem. Soc. 80 1339

    1958

  19. [27]

    Chen X, Meng D, Wang B, Li B W, Li W, Bielawski C W, Ruoff R S 2016 Carbon 101 71

    2016

  20. [28]

    Lazauskas A, Baltrusaitis J, Grigaliūnas V , Guobienė A, Prosyčevas I, Narmontas P, Abakevičienė B, Tamulevičius S 2014 Superlattices Microstruct. 75 461

    2014

  21. [29]

    Li J, Ma J, Kumar V , Fu H, Xu C, Wang S, Jia Q, Fan Q, Xi X, Li M, Liu H, Lu Y 2022 Nucleic. Acids. Res. 50 7002

    2022

  22. [30]

    Ma J B, Chen Z, Xu C H, Huang X Y , Jia Q, Zou Z Y , Mi C Y , Ma D F, Lu Y , Zhang H D, Li M 2020 Nucleic. Acids. Res. 48 3156

    2020

  23. [31]

    Chen Z, Ma J B, Huang X Y , Jia Q, Xu C H, Zhang H D, Lu Y 2018 Acta Phys. Sin. 67 118201 (in Chinese)

    2018

  24. [32]

    Wei A, Wang J X, Long Q, Liu X M, Li X G, Dong X C, Huang W 2011 Mater. Res. Bull. 46 2131

    2011

  25. [33]

    Luo D, Zhang G, Liu J, Sun X 2011 J. Phys. Chem. C. 115 11327

    2011

  26. [34]

    Xu S T, Liu J K, Xue Y , Wu T Y , Zhang Z F 2017 Fuller. Nanotub. Car. N. 25 40

    2017

  27. [35]

    Zhen X J, Huang Y F, Yang S S, Feng Z Z, Wang Y , Li C H, Miao Y J, Yin H 2020 Mater. Lett. 260 126880

    2020

  28. [36]

    Dessinges M N, Maier B, Zhang Y , Peliti M, Bensimon D, Croquette V 2002 Phys. Rev. Lett. 89 248102

    2002

  29. [37]

    Baumann C G, Smith S B, Bloomfield V A, Bustamante C 1997 Proc. Natl. Acad. Sci. U. S. A. 94 6185

    1997

  30. [38]

    Son S, Takatori S C, Belardi B, Podolski M, Bakalar M H, Fletcher D A 2020 Proc. Natl. Acad. Sci. U. S. A. 117 14209

    2020

  31. [39]

    Demirel G B, Caykara T 2009 Appl. Surf. Sci. 255 6571

    2009

  32. [40]

    Lu J R, Su T J, Thomas R K 1999 J. Colloid. Interf. Sci. 213 426

    1999

  33. [41]

    P. C. Weber J J W, f M. W. Pantoliano, and F. R. Salemme 1992 J. Am. Chem. Soc. 114 3197

    1992

  34. [42]

    Liu Y L, West S C 2004 Nat. Rev. Mol. Cell. Bio. 5 937

    2004

  35. [43]

    Clegg R M, Murchie A I, Lilley D M 1994 Biophysical. J. 66 99

    1994

  36. [44]

    McKinney S A, Tan E, Wilson T J, Nahas M K, Declais A C, Clegg R M, Lilley D M J, Ha T 2004 Biochem. Soc. T 32 41

    2004

  37. [45]

    McKinney S A, Declais A C, Lilley D M J, Ha T 2003 Nat. Struct. Biol. 10 93

    2003

  38. [46]

    Hohng S, Joo C, Ha T 2004 Biophys. J. 87 1328

    2004

  39. [47]

    Lee J, Lee S, Ragunathan K, Joo C, Ha T, Hohng S 2010 Angew. Chem. Int. Ed. Engl. 49 9922

    2010

  40. [48]

    Uphoff S, Holden S J, Le Reste L, Periz J, van de Linde S, Heilemann M, Kapanidis A N 2010 Nat. Methods. 7 831

    2010

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Reviewed August 11, 2026 · model on record in the stance chip above.