Photosensitizer

A photosensitizer is a molecule that produces a chemical change in another molecule in a photochemical process.[1] Photosensitizers are commonly used in polymer chemistry in reactions such as photopolymerization, photocrosslinking, and photodegradation.[2] Photosensitizers are also used to generate triplet excited states in organic molecules with uses in photocatalysis, photon upconversion and photodynamic therapy. Photosensitizers generally act by absorbing ultraviolet or visible region of electromagnetic radiation and transferring it to adjacent molecules. Photosensitizers usually have large de-localized π systems, which lower the energy of HOMO orbitals and its absorption of light might be able to ionize the molecule. There are also examples of using semiconductor quantum dots as photosensitizers.[3]

A photosensitizer being used in photodynamic therapy.

Chlorophyll acts as a photosensitizer during the photosynthesis of carbohydrates in plants: 6CO2 + 6H2O → C6H12O6 + 6O2

Applications

Medical

Photosensitisers are a part of photodynamic therapy (PDT) which is used to treat some cancers. They help to produce singlet oxygen to damage tumours. They can be divided into porphyrins, chlorophylls and dyes - See Photodynamic_therapy#Photosensitizers

In February 2019, medical scientists announced that iridium attached to albumin, creating a photosensitized molecule, can penetrate cancer cells and, after being irradiated with light (a process called photodynamic therapy), destroy the cancer cells.[4][5]

See also

References
  1. "Photosensitization". IUPAC Compendium of Chemical Terminology. 2009. doi:10.1351/goldbook.P04652. ISBN 978-0-9678550-9-7.
  2. Alger, Mark (1996). Polymer science dictionary (2nd ed.). London: Chapman & Hall. ISBN 978-0412608704.
  3. Mongin, C.; et al. (2015). "Weaving of organic threads into a crystalline covalent organic framework". Science. 351 (6271): 369–372. doi:10.1126/science.aad4011. PMID 26798010.
  4. University of Warwick (3 February 2019). "Simply shining light on dinosaur metal compound kills cancer cells". EurekAlert!. Retrieved 3 February 2019.
  5. Zhang, Pingyu; et al. (15 December 2018). "Nucleus‐Targeted Organoiridium–Albumin Conjugate for Photodynamic Cancer Therapy". Angewandte Chemie. 58 (8): 2350–2354. doi:10.1002/anie.201813002. PMC 6468315. PMID 30552796.


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