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Biophotons (from the Greek βίος meaning "life" and φῶς meaning "light") are photons of light in the ultraviolet and low visible light range that are produced by a biological system. They are non-thermal in origin, and the emission of biophotons is technically a type of bioluminescence, though bioluminescence is generally reserved for higher luminance luciferin/luciferase systems. The term biophoton used in this narrow sense should not be confused with the broader field of biophotonics, which studies the general interaction of light with biological systems.

Biological tissues typically produce an observed radiant emittance in the visible and ultraviolet frequencies ranging from 10−17 to 10−23 W/cm2 (approx 1-1000 photons/cm2/second).[1] This low level of light has a much weaker intensity than the visible light produced by bioluminescence, but biophotons are detectable above the background of thermal radiation that is emitted by tissues at their normal temperature.[2]

While detection of biophotons has been reported by several groups,[3][4][5] hypotheses that such biophotons indicate the state of biological tissues and facilitate a form of cellular communication are still under investigation,[6][7] Alexander Gurwitsch, who discovered the existence of biophotons, was awarded the Stalin Prize in 1941 for his work.[8]

Detection and measurement[edit]

Biophotons may be detected with photomultipliers or by means of an ultra low noise CCD camera to produce an image, using an exposure time of typically 15 minutes for plant materials.[9][3] Photomultiplier tubes have been used to measure biophoton emissions from fish eggs,[10] and some applications have measured biophotons from animals and humans.[11][12][13] Electron Multiplying CCD (EM-CCD) optimized for the detection of ultraweak light[14] have also been used to detect the bioluminescence produced by yeast cells at the onset of their growth.[15]

The typical observed radiant emittance of biological tissues in the visible and ultraviolet frequencies ranges from 10−17 to 10−23 W/cm2 with a photon count from a few to nearly 1000 photons per cm2 in the range of 200 nm to 800 nm.[1]

Proposed physical mechanisms[edit]

Chemi-excitation via oxidative stress by reactive oxygen species and/or catalysis by enzymes (i.e., peroxidase, lipoxygenase) is a common event in the biomolecular milieu.[16] Such reactions can lead to the formation of triplet excited species, which release photons upon returning to a lower energy level in a process analogous to phosphorescence. That this process is a contributing factor to spontaneous biophoton emission has been indicated by studies demonstrating that biophoton emission can be increased by depleting assayed tissue of antioxidants[17] or by addition of carbonyl derivatizing agents.[18] Further support is provided by studies indicating that emission can be increased by addition of reactive oxygen species.[19]


Imaging of biophotons from leaves has been used as a method for assaying R gene responses.[9] These genes and their associated proteins are responsible for pathogen recognition and activation of defense signaling networks leading to the hypersensitive response,[20] which is one of the mechanisms of the resistance of plants to pathogen infection. It involves the generation of reactive oxygen species (ROS), which have crucial roles in signal transduction or as toxic agents leading to cell death.[21]

Biophotons have been also observed in the roots of stressed plants. In healthy cells, the concentration of ROS is minimized by a system of biological antioxidants. However, heat shock and other stresses changes the equilibrium between oxidative stress and antioxidant activity, for example, the rapid rise in temperature induces biophoton emission by ROS.[22]

Hypothesized involvement in cellular communication[edit]

In the 1920s, the Russian embryologist Alexander Gurwitsch reported "ultraweak" photon emissions from living tissues in the UV-range of the spectrum. He named them "mitogenetic rays" because his experiments convinced him that they had a stimulating effect on cell division.[23]

In the 1970s Fritz-Albert Popp and his research group at the University of Marburg (Germany) showed that the spectral distribution of the emission fell over a wide range of wavelengths, from 200 to 750 nm.[24] Popp's work on the biophoton emission's statistical properties, namely the claims on its coherence, was criticised for lack of scientific rigour.[2]

One biophoton mechanism focuses on injured cells that are under higher levels of oxidative stress, which is one source of light, and can be deemed to constitute a "distress signal" or background chemical process, but this mechanism is yet to be demonstrated.[citation needed] The difficulty of teasing out the effects of any supposed biophotons amid the other numerous chemical interactions between cells makes it difficult to devise a testable hypothesis. A 2010 review article discusses various published theories on this kind of signaling.[25]

The hypothesis of cellular communication by biophotons was highly criticised for failing to explain how could cells detect photonic signals several orders of magnitude weaker than the natural background illumination.[26]

See also[edit]


  1. ^ a b Popp FA (May 2003). "Properties of biophotons and their theoretical implications". Indian Journal of Experimental Biology. 41 (5): 391–402. PMID 15244259.
  2. ^ a b Cifra M, Brouder C, Nerudová M, Kučera O (2015). "Biophotons, coherence and photocount statistics: A critical review". Journal of Luminescence. 164: 38–51. arXiv:1502.07316. Bibcode:2015JLum..164...38C. doi:10.1016/j.jlumin.2015.03.020. S2CID 97425113.
  3. ^ a b Takeda M, Kobayashi M, Takayama M, Suzuki S, Ishida T, Ohnuki K, et al. (August 2004). "Biophoton detection as a novel technique for cancer imaging". Cancer Science. 95 (8): 656–61. doi:10.1111/j.1349-7006.2004.tb03325.x. PMID 15298728. S2CID 21875229.
  4. ^ Rastogi A, Pospísil P (August 2010). "Ultra-weak photon emission as a non-invasive tool for monitoring of oxidative processes in the epidermal cells of human skin: comparative study on the dorsal and the palm side of the hand". Skin Research and Technology. 16 (3): 365–70. doi:10.1111/j.1600-0846.2010.00442.x. PMID 20637006. S2CID 24243914.
  5. ^ Niggli HJ (May 1993). "Artificial sunlight irradiation induces ultraweak photon emission in human skin fibroblasts". Journal of Photochemistry and Photobiology B: Biology. 18 (2–3): 281–5. doi:10.1016/1011-1344(93)80076-L. PMID 8350193.
  6. ^ Bajpai R (2009). "Biophotons: a clue to unravel the mystery of "life"". In Meyer-Rochow VB (ed.). Bioluminescence in Focus - a collection of illuminating essays. Vol. 1. Kerala, India: Research Signpost. pp. 357–385. ISBN 9788130803579. OCLC 497860307.
  7. ^ Zarkeshian P, Kumar S, Tuszynski J, Barclay P, Simon C (March 2018). "Are there optical communication channels in the brain?". Frontiers in Bioscience (Landmark Edition). 23 (8): 1407–1421. arXiv:1708.08887. doi:10.2741/4652. PMID 29293442. S2CID 29847303.
  8. ^ Beloussov LV, Opitz JM, Gilbert SF (December 1997). "Life of Alexander G. Gurwitsch and his relevant contribution to the theory of morphogenetic fields". The International Journal of Developmental Biology. 41 (6): 771–7, comment 778–9. PMID 9449452.
  9. ^ a b Bennett M, Mehta M, Grant M (February 2005). "Biophoton imaging: a nondestructive method for assaying R gene responses". Molecular Plant-Microbe Interactions. 18 (2): 95–102. doi:10.1094/MPMI-18-0095. PMID 15720077.
  10. ^ Yirka B (May 2012). "Research suggests cells communicate via biophotons". Retrieved 26 January 2016.
  11. ^ Kobayashi M, Kikuchi D, Okamura H (July 2009). "Imaging of ultraweak spontaneous photon emission from human body displaying diurnal rhythm". PLOS ONE. 4 (7): e6256. Bibcode:2009PLoSO...4.6256K. doi:10.1371/journal.pone.0006256. PMC 2707605. PMID 19606225.
  12. ^ Dotta BT, Saroka KS, Persinger MA (April 2012). "Increased photon emission from the head while imagining light in the dark is correlated with changes in electroencephalographic power: support for Bókkon's biophoton hypothesis". Neuroscience Letters. 513 (2): 151–4. doi:10.1016/j.neulet.2012.02.021. PMID 22343311. S2CID 207135123.
  13. ^ Joines WT, Baumann SB, Kruth JG (2012). "Electromagnetic emission from humans during focused intent". Journal of Parapsychology. 76 (2): 275–294.
  14. ^ Khaoua I, Graciani G, Kim A, Amblard F (February 2021). "Detectivity optimization to detect of ultraweak light fluxes with an EM-CCD as binary photon counter array". Scientific Reports. 11 (1): 3530. Bibcode:2021NatSR..11.3530K. doi:10.1038/s41598-021-82611-8. PMC 7878522. PMID 33574351.
  15. ^ Khaoua I, Graciani G, Kim A, Amblard F (May 2021). "Stochastic light concentration from 3D to 2D reveals ultraweak chemi- and bioluminescence". Scientific Reports. 11 (1): 10050. Bibcode:2021NatSR..1110050K. doi:10.1038/s41598-021-88091-0. PMC 8113247. PMID 33976267.
  16. ^ Cilento G, Adam W (July 1995). "From free radicals to electronically excited species". Free Radical Biology & Medicine. 19 (1): 103–14. doi:10.1016/0891-5849(95)00002-F. PMID 7635351.
  17. ^ Ursini F, Barsacchi R, Pelosi G, Benassi A (July 1989). "Oxidative stress in the rat heart, studies on low-level chemiluminescence". Journal of Bioluminescence and Chemiluminescence. 4 (1): 241–4. doi:10.1002/bio.1170040134. PMID 2801215.
  18. ^ Kataoka Y, Cui Y, Yamagata A, Niigaki M, Hirohata T, Oishi N, Watanabe Y (July 2001). "Activity-dependent neural tissue oxidation emits intrinsic ultraweak photons". Biochemical and Biophysical Research Communications. 285 (4): 1007–11. doi:10.1006/bbrc.2001.5285. PMID 11467852.
  19. ^ Boveris A, Cadenas E, Reiter R, Filipkowski M, Nakase Y, Chance B (January 1980). "Organ chemiluminescence: noninvasive assay for oxidative radical reactions". Proceedings of the National Academy of Sciences of the United States of America. 77 (1): 347–51. Bibcode:1980PNAS...77..347B. doi:10.1073/pnas.77.1.347. PMC 348267. PMID 6928628.
  20. ^ Iniguez AL, Dong Y, Carter HD, Ahmer BM, Stone JM, Triplett EW (February 2005). "Regulation of enteric endophytic bacterial colonization by plant defenses". Molecular Plant-Microbe Interactions. 18 (2): 169–78. doi:10.1094/MPMI-18-0169. PMID 15720086.
  21. ^ Kobayashi M, Sasaki K, Enomoto M, Ehara Y (2006). "Highly sensitive determination of transient generation of biophotons during hypersensitive response to cucumber mosaic virus in cowpea". Journal of Experimental Botany. 58 (3): 465–72. doi:10.1093/jxb/erl215. PMID 17158510.
  22. ^ Kobayashi K, Okabe H, Kawano S, Hidaka Y, Hara K (2014). "Biophoton emission induced by heat shock". PLOS ONE. 9 (8): e105700. Bibcode:2014PLoSO...9j5700K. doi:10.1371/journal.pone.0105700. PMC 4143285. PMID 25153902.
  23. ^ Gurwitsch AA (July 1988). "A historical review of the problem of mitogenetic radiation". Experientia. 44 (7): 545–50. doi:10.1007/bf01953301. PMID 3294029. S2CID 10930945.
  24. ^ Wijk RV, Wijk EP (April 2005). "An Introduction to Human Biophoton Emission". Forschende Komplementärmedizin und Klassische Naturheilkunde. 12 (2): 77–83. doi:10.1159/000083763. PMID 15947465. S2CID 25794113.
  25. ^ Cifra M, Fields JZ, Farhadi A (May 2011). "Electromagnetic cellular interactions". Progress in Biophysics and Molecular Biology. 105 (3): 223–46. doi:10.1016/j.pbiomolbio.2010.07.003. PMID 20674588.
  26. ^ Kučera O, Cifra M (November 2013). "Cell-to-cell signaling through light: just a ghost of chance?". Cell Communication and Signaling. 11 (87): 87. doi:10.1186/1478-811X-11-87. PMC 3832222. PMID 24219796.

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