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arxiv: 1907.00065 · v2 · pith:J5JWM757new · submitted 2019-06-28 · ⚛️ physics.app-ph · physics.bio-ph

Radiation Brightening from Virus-like Particles

Irina B. Tsvetkova , Arathi Anil Sushma , Joseph C.-Y. Wang , William L. Schaich , Bogdan Dragnea This is my paper

Pith reviewed 2026-05-25 12:37 UTC · model grok-4.3

classification ⚛️ physics.app-ph physics.bio-ph
keywords concentration quenchingfluorescence brighteningvirus-like particleschromophorespulsed excitationcollective relaxationsurface density
0
0 comments X

The pith

Densely packed chromophores on virus particles show sudden fluorescence brightening and shorter lifetimes under short-pulse excitation.

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

As the number of chromophores attached to the surface of 28-nm virus particles increases, emission first decreases due to concentration quenching. At densities approaching the maximum number of binding sites, however, the emission suddenly increases and the excited-state lifetime shortens, but only when the particles are excited with short light pulses. Under continuous illumination the usual quenching behavior persists at all densities. The effect vanishes when the spatial arrangement or motion of the chromophores becomes more disordered, indicating that the regular virus surface may promote a collective relaxation process among the emitters.

Core claim

The optical emission from hundreds of chromophores confined onto the surface of a virus particle can be recovered under pulsed irradiation. As one increases the number of chromophores tightly-bound to the virus surface, fluorescence quenching ensues at first, but when the number of chromophores per particle is nearing the maximum number of surface sites allowable, a sudden brightening of the emitted light and a shortening of the excited state lifetime are observed. This radiation brightening occurs only under short pulse excitation; steady-state excitation is characterized by conventional concentration quenching for any number of chromophores per particle. The observed suppression of thequex

What carries the argument

Virus particle surface with near-maximum chromophore occupancy enabling collective relaxation under pulsed excitation

If this is right

  • Radiation brightening requires short-pulse excitation and does not occur under steady-state conditions.
  • The brightening is suppressed by increased emitter heterogeneity, linking the effect to low-disorder surface packing.
  • The virus template produces optical behavior distinct from conventional concentration quenching in biophotonic agents.
  • High-density labeling on such particles can recover emission intensity that would otherwise be lost to quenching.

Where Pith is reading between the lines

These are editorial extensions of the paper, not claims the author makes directly.

  • The same brightening might appear on other rigid, ordered nanoparticle surfaces if chromophore packing density and homogeneity can be controlled similarly.
  • Varying pulse length could reveal the timescale over which the collective process operates.
  • Engineering surface regularity on synthetic carriers could replicate the effect without using biological templates.

Load-bearing premise

The assumption that the disappearance of brightening with increased spatial and/or dynamic heterogeneity demonstrates that the virus template structural properties enable the collective relaxation, rather than other uncontrolled factors in particle preparation or excitation conditions.

What would settle it

Observing that radiation brightening persists after deliberately increasing spatial or dynamic heterogeneity of the chromophores on the virus particles would falsify the claim that template structural properties are required for collective relaxation.

Figures

Figures reproduced from arXiv: 1907.00065 by Arathi Anil Sushma, Bogdan Dragnea, Irina B. Tsvetkova, Joseph C.-Y. Wang, William L. Schaich.

Figure 1
Figure 1. Figure 1: A) Molecular model of BMV with structure surface exposed lysines. B) OG [PITH_FULL_IMAGE:figures/full_fig_p005_1.png] view at source ↗
Figure 2
Figure 2. Figure 2: Steady-state UV-Vis absorption (A) and fluorescence emission (B) spectra of [PITH_FULL_IMAGE:figures/full_fig_p006_2.png] view at source ↗
Figure 3
Figure 3. Figure 3: shows the distributions of the fluorescence lifetime and time-integrated photon counts from single OG-BMV particles with different Ns under supercontinuum pulsed irra￾diation. In Fig. 3A, FLIM was carried at 90% of the maximum laser power (i.e. ∼ 450 µW at the sample), while in Fig. 3B only 15% of the maximum laser power (∼ 75 µW at the sample) was used [PITH_FULL_IMAGE:figures/full_fig_p008_3.png] view at source ↗
Figure 4
Figure 4. Figure 4: Scatter plots of estimated lifetime vs fluorescence photon counts at same laser [PITH_FULL_IMAGE:figures/full_fig_p010_4.png] view at source ↗
Figure 5
Figure 5. Figure 5: A. Normalized fluorescence spectra for free dye and samples with low and high [PITH_FULL_IMAGE:figures/full_fig_p012_5.png] view at source ↗
read the original abstract

Concentration quenching is a well-known challenge in many fluorescence imaging applications. Here we show that the optical emission from hundreds of chromophores confined onto the surface of a virus particle 28 nm diameter can be recovered under pulsed irradiation. We have found that, as one increases the number of chromophores tightly-bound to the virus surface, fluorescence quenching ensues at first, but when the number of chromophores per particle is nearing the maximum number of surface sites allowable, a sudden brightening of the emitted light and a shortening of the excited state lifetime are observed. This radiation brightening occurs only under short pulse excitation; steady-state excitation is characterized by conventional concentration quenching for any number of chromophores per particle. The observed suppression of fluorescence quenching is consistent with efficient, collective relaxation at room temperature. Interestingly, radiation brightening disappears when the emitters' spatial and/or dynamic heterogeneity is increased, suggesting that the template structural properties may play a role and opening a way towards novel, virus-enabled imaging vectors that have qualitatively different optical properties than state-of-the-art biophotonic agents.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Referee Report

2 major / 0 minor

Summary. The manuscript reports an experimental observation on virus-like particles (28 nm diameter) with surface-bound chromophores. As the number of chromophores increases, conventional concentration quenching occurs initially, but near the maximum allowable surface sites a sudden brightening and shortened excited-state lifetime appear under short-pulse excitation (absent under steady-state excitation). The brightening vanishes upon increasing spatial and/or dynamic heterogeneity of the emitters, which the authors interpret as evidence that the virus template's structural regularity enables collective relaxation at room temperature, potentially enabling new virus-based imaging vectors.

Significance. If the central observation is reproducible and the heterogeneity test isolates the template role, the result would be significant for biophotonics by demonstrating a route to suppress quenching via collective effects on a regular nanoscale template. No machine-checked proofs, reproducible code, or parameter-free derivations are described.

major comments (2)
  1. [Abstract] Abstract: The key observation (brightening near maximum surface coverage under pulsed excitation, its absence under steady-state, and its disappearance with heterogeneity) is stated without any data, figures, error bars, sample sizes, controls, or quantitative metrics, so it is not possible to determine whether the data support the claim.
  2. [Abstract (heterogeneity discussion)] Heterogeneity test (as described in the abstract): The observation that brightening vanishes with increased spatial/dynamic heterogeneity is interpreted as showing that virus template structural properties enable collective relaxation. However, the test does not isolate template regularity; increased heterogeneity could simultaneously alter chromophore-virus binding uniformity, local dielectric environment, aggregation, or effective excitation fluence, any of which could suppress the effect without reference to collective modes.

Simulated Author's Rebuttal

2 responses · 0 unresolved

We thank the referee for their careful reading of our manuscript and for the constructive comments. We provide point-by-point responses to the major comments below.

read point-by-point responses

  1. Referee: [Abstract] Abstract: The key observation (brightening near maximum surface coverage under pulsed excitation, its absence under steady-state, and its disappearance with heterogeneity) is stated without any data, figures, error bars, sample sizes, controls, or quantitative metrics, so it is not possible to determine whether the data support the claim.

    Authors: We note that the abstract serves as a high-level summary of the results, while the full manuscript contains the supporting data, figures with error bars, sample sizes, and controls. To better address the referee's point, we will update the abstract to include key quantitative metrics, such as the magnitude of the brightening effect and typical experimental statistics. revision: yes

  2. Referee: [Abstract (heterogeneity discussion)] Heterogeneity test (as described in the abstract): The observation that brightening vanishes with increased spatial/dynamic heterogeneity is interpreted as showing that virus template structural properties enable collective relaxation. However, the test does not isolate template regularity; increased heterogeneity could simultaneously alter chromophore-virus binding uniformity, local dielectric environment, aggregation, or effective excitation fluence, any of which could suppress the effect without reference to collective modes.

    Authors: The referee correctly identifies that the heterogeneity test, while showing the effect's sensitivity to emitter uniformity, does not exclusively prove the role of the virus template's regularity, as other variables may be affected. Our interpretation is based on the virus particles providing a uniquely regular template compared to other systems. In the revision, we will revise the abstract and main text to present the collective relaxation as a consistent interpretation rather than a definitive conclusion, and we will elaborate on potential alternative mechanisms. revision: partial

Circularity Check

0 steps flagged

No derivation chain; purely experimental observations

full rationale

The paper reports direct experimental measurements of fluorescence intensity, lifetime, and quenching/brightening behavior as a function of chromophore loading on virus particles under pulsed vs. steady-state excitation, plus a heterogeneity test. No equations, fitted parameters, predictions derived from models, or self-citations appear in the provided text or abstract. The central claim is an observed phenomenon (brightening near saturation under short pulses) whose interpretation is presented as consistent with collective relaxation, but the report itself contains no derivation that reduces to its inputs. The heterogeneity observation is an empirical control, not a mathematical step. This is a standard experimental paper with no circularity risk of the enumerated kinds.

Axiom & Free-Parameter Ledger

0 free parameters · 1 axioms · 0 invented entities

The central claim rests on an experimental observation rather than a derivation. No free parameters are introduced. The only axiom is the standard domain assumption of concentration quenching under steady-state conditions.

axioms (1)
  • domain assumption Concentration quenching occurs for densely packed chromophores under steady-state excitation.
    The paper contrasts its pulsed-excitation result against this established behavior.

pith-pipeline@v0.9.0 · 5730 in / 1197 out tokens · 60537 ms · 2026-05-25T12:37:16.939063+00:00 · methodology

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Reference graph

Works this paper leans on

49 extracted references · 49 canonical work pages

  1. [1]

    E.; Warram, J

    Tipirneni, K. E.; Warram, J. M.; Moore, L. S.; Prince, A. C.; de Boer, E.; Jani, A. H.; Wapnir, I. L.; Liao, J. C.; Bouvet, M.; Behnke, N. K. et al. Oncologic Procedures Amenable to Fluorescence-guided Surgery. Ann. Surg. 2017, 266, 36–47

    work page 2017

  2. [2]

    Fluorescent and magnetic anti-counterfeiting realized by biocompatible multifunctional silicon nanoshuttle-based security ink

    Song, B.; Wang, H.; Zhong, Y.; Chu, B.; Su, Y.; He, Y. Fluorescent and magnetic anti-counterfeiting realized by biocompatible multifunctional silicon nanoshuttle-based security ink. Nanoscale 2018, 10, 1617–1621

    work page 2018

  3. [3]

    V.; Stepanenko, O

    Stepanenko, O. V.; Stepanenko, O. V.; Shcherbakova, D. M.; Kuznetsova, I. M.; Tur- overov, K. K.; Verkhusha, V. V. Modern fluorescent proteins: from chromophore forma- tion to novel intracellular applications. Biotechniques 2011, 51, 313–318

    work page 2011

  4. [4]

    Tsien, R. Y. Roger Y. Tsien - Nobel Lecture: Constructing and Exploiting the Fluores- cent Protein Paintbox. 2008; https://www.nobelprize.org/

    work page 2008

  5. [5]

    Valeur, B.; Berberan-Santos, M. r. N. John Wiley Sons , 2nd ed.; Principles and Appli- cations; John Wiley & Sons: New York, 2013

    work page 2013

  6. [6]

    Khitrova, G.; Gibbs, H. M. Collective radiance. Nat. Phys. 2007, 3, 84–85

    work page 2007

  7. [7]

    Dicke, R. H. Coherence in Spontaneous Radiation Processes. Phys. Rev. 1954, 93, 99– 110

    work page 1954

  8. [8]

    Physics of life: The dawn of quantum biology

    Ball, P. Physics of life: The dawn of quantum biology. Nature 2011, 474, 272–274

    work page 2011

  9. [9]

    D.; Fleming, G

    Scholes, G. D.; Fleming, G. R.; Olaya-Castro, A.; van Grondelle, R. Lessons from nature about solar light harvesting. Nat. Chem. 2011, 3, 763–774

    work page 2011

  10. [10]

    Superradiance and Exciton Delocalization in Bacterial Photosynthetic Light-Harvesting Systems

    Monshouwer, R.; Abrahamsson, M.; van Mourik, F.; van Grondelle, R. Superradiance and Exciton Delocalization in Bacterial Photosynthetic Light-Harvesting Systems. J. Phys. Chem. B 1997, 101, 7241–7248. 20

    work page 1997

  11. [11]

    Purcell, E. M. Spontaneous emission probabilities at radio frequencies. Proc. Am. Phys. Soc. 1946; p 681

    work page 1946

  12. [12]

    Superfluorescence: macroscopic quantum fluc- tuations in the time domain

    Vrehen, Q.; Schuurmans, M.; Polder, D. Superfluorescence: macroscopic quantum fluc- tuations in the time domain. Nature 1980, 285, 70–71

    work page 1980

  13. [13]

    Superradiance: An essay on the theory of collective spontaneous emission

    Gross, M.; Haroche, S. Superradiance: An essay on the theory of collective spontaneous emission. Phys. Rep. 1982, 93, 301–396

    work page 1982

  14. [14]

    Benedict, M. G. M. G. Super-radiance : multiatomic coherent emmission ; Institute of Physics Pub, 1996; p 326

    work page 1996

  15. [15]

    T.; Belyanin, A.; Kono, J

    Cong, K.; Zhang, Q.; Wang, Y.; Noe, G. T.; Belyanin, A.; Kono, J. Dicke superradiance in solids [Invited]. J. Opt. Soc. Am. B 2016, 33, C80

    work page 2016

  16. [16]

    Mallawa Arachchi, S.; Premaratne, M.; Maini, P. K. Superradiant Cancer Hyperthermia using a Buckyball Assembly of Quantum Dot Emitters. IEEE J. Sel. Top. Quantum Electron. 2018, 1–1

    work page 2018

  17. [17]

    Nanomaterial-Enabled Neural Stimulation

    Wang, Y.; Guo, L. Nanomaterial-Enabled Neural Stimulation. Front. Neurosci. 2016, 10

    work page 2016

  18. [18]

    P.; MacGillivray, J

    Skribanowitz, N.; Herman, I. P.; MacGillivray, J. C.; Feld, M. S. Observation of Dicke Superradiance in Optically Pumped HF Gas. Phys. Rev. Lett. 1973, 30, 309–312

    work page 1973

  19. [19]

    S.; Maki, J

    Malcuit, M. S.; Maki, J. J.; Simkin, D. J.; Boyd, R. W. Transition from superfluorescence to amplified spontaneous emission. Phys. Rev. Lett. 1987, 59, 1189–1192

    work page 1987

  20. [20]

    Superradiance of quantum dots

    Scheibner, M.; Schmidt, T.; Worschech, L.; Forchel, A.; Bacher, G.; Passow, T.; Hom- mel, D. Superradiance of quantum dots. Nat. Phys. 2007, 3, 106–110

    work page 2007

  21. [21]

    C.; Mukamel, S

    Spano, F. C.; Mukamel, S. Superradiance in molecular aggregates. J. Chem. Phys. 1989, 91, 683–700. 21

    work page 1989

  22. [22]

    T.; van Breugel, M.; Baragiola, B

    Bradac, C.; Johnsson, M. T.; van Breugel, M.; Baragiola, B. Q.; Martin, R.; Juan, M. L.; Brennen, G. K.; Volz, T. Room-temperature spontaneous superradiance from single diamond nanocrystals. Nat. Commun. 2017, 8, 1205

    work page 2017

  23. [23]

    W.; Larson, S

    Lucas, R. W.; Larson, S. B.; McPherson, A. The crystallographic structure of brome mosaic virus. J. Mol. Biol. 2002, 317, 95–108

    work page 2002

  24. [24]

    Spano, F. C. The Spectral Signatures of Frenkel Polarons in H- and J-Aggregates. Acc. Chem. Res. 2010, 43, 429–439

    work page 2010

  25. [25]

    M.; Steinmetz, N

    Wen, A. M.; Steinmetz, N. F. Design of virus-based nanomaterials for medicine, biotech- nology, and energy. Chem. Soc. Rev. 2016, 45, 4074–4126

    work page 2016

  26. [26]

    M.; Blum, A

    Soto, C. M.; Blum, A. S.; Vora, G. J.; Lebedev, N.; Meador, C. E.; Won, A. P.; Chat- terji, A.; Johnson, J. E.; Ratna, B. R. Fluorescent Signal Amplification of Carbocyanine Dyes Using Engineered Viral Nanoparticles. J. Am. Chem. Soc. 2006, 128, 5184–5189

    work page 2006

  27. [27]

    Superradiance, coherence brightening and amplified spontaneous emission

    Allen, L.; Peters, G. Superradiance, coherence brightening and amplified spontaneous emission. Phys. Lett. A 1970, 31, 95–96

    work page 1970

  28. [28]

    Superradiance with local phase- breaking effects

    Shammah, N.; Lambert, N.; Nori, F.; De Liberato, S. Superradiance with local phase- breaking effects. Phys. Rev. A 2017, 96, 023863

    work page 2017

  29. [29]

    Shahbazyan, T. V. Mode Volume, Energy Transfer, and Spaser Threshold in Plasmonic Systems with Gain. ACS Photonics 2017, 4, 1003–1008

    work page 2017

  30. [30]

    Samuel, I. D. W.; Namdas, E. B.; Turnbull, G. A. How to recognize lasing.Nat. Photonics 2009, 3, 546–549

    work page 2009

  31. [31]

    Allen, L.; Peters, G. I. Amplified Spontaneous Emission and External Signal Amplifica- tion in an Inverted Medium. Phys. Rev. A 1973, 8, 2031–2047

    work page 1973

  32. [32]

    M.; Knobler, C

    Gelbart, W. M.; Knobler, C. M. VIROLOGY: Pressurized Viruses. Science 2009, 323, 1682–1683. 22

    work page 2009

  33. [33]

    Structure and mechanochemistry of icosahedral viruses and virus shells studied by atomic force microscopy

    Zeng, C. Structure and mechanochemistry of icosahedral viruses and virus shells studied by atomic force microscopy. Ph.D. thesis, Indiana University, Bloomington, 2017

    work page 2017

  34. [34]

    Arakawa, T.; Timasheff, S. N. Mechanism of polyethylene glycol interaction with pro- teins. Biochemistry 1985, 24, 6756–6762

    work page 1985

  35. [35]

    B.; Shkel, I

    Knowles, D. B.; Shkel, I. A.; Phan, N. M.; Sternke, M.; Lingeman, E.; Cheng, X.; Cheng, L.; O’Connor, K.; Record, M. T. Chemical Interactions of Polyethylene Glycols (PEGs) and Glycerol with Protein Functional Groups: Applications to Effects of PEG and Glycerol on Protein Processes. Biochemistry 2015, 54, 3528–3542

    work page 2015

  36. [36]

    Fermi’s golden rule does not ade- quately describe Dicke’s superradiance

    Svidzinsky, A.; Chang, J.-T.; Lipkin, H.; Scully, M. Fermi’s golden rule does not ade- quately describe Dicke’s superradiance. J. Mod. Opt. 2008, 55, 3369–3378

    work page 2008

  37. [37]

    T.; Haberstroh, J.; Geissler, P

    Noriega, R.; Finley, D. T.; Haberstroh, J.; Geissler, P. L.; Francis, M. B.; Ginsberg, N. S. Manipulating Excited-State Dynamics of Individual Light-Harvesting Chromophores through Restricted Motions in a Hydrated Nanoscale Protein Cavity. J. Phys. Chem. B 2015, 119, 6963–73

    work page 2015

  38. [38]

    P.; Steude, A.; Tropf, L.; Schubert, M.; Kronenberg, N

    Dietrich, C. P.; Steude, A.; Tropf, L.; Schubert, M.; Kronenberg, N. M.; Ostermann, K.; H¨ ofling, S.; Gather, M. C. An exciton-polariton laser based on biologically produced fluorescent protein. Sci. Adv. 2016, 2, e1600666

    work page 2016

  39. [39]

    Photon antibunching

    Paul, H. Photon antibunching. Rev. Mod. Phys. 1982, 54, 1061–1102

    work page 1982

  40. [40]

    M.; Holzenburg, A

    Sun, J.; DuFort, C.; Daniel, M.-C.; Murali, A.; Chen, C.; Gopinath, K.; Stein, B.; De, M.; Rotello, V. M.; Holzenburg, A. et al. Core-controlled polymorphism in virus-like particles. Proc. Natl. Acad. Sci. U. S. A. 2007, 104, 1354–1359

    work page 2007

  41. [41]

    V.; Dashti, N.; Thuenemann, E

    Brillault, L.; Jutras, P. V.; Dashti, N.; Thuenemann, E. C.; Morgan, G.; Lomonos- soff, G. P.; Landsberg, M. J.; Sainsbury, F. Engineering Recombinant Virus-like Nanoparticles from Plants for Cellular Delivery. ACS Nano 2017, 11, 3476–3484. 23

    work page 2017

  42. [42]

    Lang, K.; Chin, J. W. Cellular Incorporation of Unnatural Amino Acids and Bioorthog- onal Labeling of Proteins. Chem. Rev. 2014, 114, 4764–4806

    work page 2014

  43. [43]

    Gopinath, K.; Kao, C. C. Replication-independent long-distance trafficking by viral RNAs in Nicotiana benthamiana. Plant Cell 2007, 19, 1179–91

    work page 2007

  44. [44]

    E.; Tataurova, Y.; Mueller, P

    Lehman, S. E.; Tataurova, Y.; Mueller, P. S.; Mariappan, S. V. S.; Larsen, S. C. Lig- and Characterization of Covalently Functionalized Mesoporous Silica Nanoparticles: An NMR Toolbox Approach. J. Phys. Chem. C 2014, 118, 29943–29951

    work page 2014

  45. [45]

    Q.; Palovcak, E.; Armache, J.-P.; Verba, K

    Zheng, S. Q.; Palovcak, E.; Armache, J.-P.; Verba, K. A.; Cheng, Y.; Agard, D. A. MotionCor2: anisotropic correction of beam-induced motion for improved cryo-electron microscopy. Nat. Methods 2017, 14, 331–332

    work page 2017

  46. [46]

    CTFFIND4: Fast and accurate defocus estimation from elec- tron micrographs

    Rohou, A.; Grigorieff, N. CTFFIND4: Fast and accurate defocus estimation from elec- tron micrographs. J. Struct. Biol. 2015, 192, 216–221

    work page 2015

  47. [47]

    R.; Mann, D

    Tang, G.; Peng, L.; Baldwin, P. R.; Mann, D. S.; Jiang, W.; Rees, I.; Ludtke, S. J. EMAN2: An extensible image processing suite for electron microscopy. J. Struct. Biol. 2007, 157, 38–46

    work page 2007

  48. [48]

    Scheres, S. H. RELION: Implementation of a Bayesian approach to cryo-EM structure determination. J. Struct. Biol. 2012, 180, 519–530

    work page 2012

  49. [49]

    F.; Goddard, T

    Pettersen, E. F.; Goddard, T. D.; Huang, C. C.; Couch, G. S.; Greenblatt, D. M.; Meng, E. C.; Ferrin, T. E. UCSF Chimera - A visualization system for exploratory research and analysis. J. Comput. Chem. 2004, 25, 1605–1612. Acknowledgement The work was supported by the Army Research Office, under award W911NF-17-1-0329, and by the National Science Foundation...

    work page 2004