Talk:Photobleaching

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Untitled[edit]

The tag at the bottom of this page (the stub indicator) is cell biology but this is more of a physics / chemistry topic. I am not sure if its important, but it may be more likely that someone with the necessary skills and background will find the page if it is differently labelled.

Also (and again I'm not sure about this) I'm not certain that photobleaching means the same thing in FRAP as it does in standard fluorescence experiments. I also think the idea of lifetimes is a little confused - fluorescence lifetimes are the length of time between absorption of excitation energy and emission of the photon by the flourophore. The changes which occur to the flourophore during this time give important information. Of course their may be more than one use of the term lifetime - this could be one of those situations where cell biologists and biophysicists use the same name to describe different phenomena.

FRAP stands for fluoresence recovery after photobleaching, as far as I can tell this method is based around the formation of a chemically long lived, but nonetheless temporary formation of a triple excited state which does not fluoresce. Photobleaching in standard flourescence experiments is permanent and the result of covalent modification to the protein following free radical formation due to prolonged exposure to UV light. From the strategene website http://www.stratagene.com/lit/faq/faq.aspx?fqid=323...

Photobleaching or fading is the loss of fluorescence with exposure to light. It occurs when a fluorophore permanently loses the ability to fluoresce due to photon-induced chemical damage and covalent modification. Minimizing the exposure of dye-containing samples to light will help reduce photobleaching, as will shorter exposures to the high intensity light used for fluorescence microscopy.

I am not sufficently knowledgable to want to edit this page, but I think that it will need to be divided into two sections, the first considering photobleaching w.r.t. FRAP and the second w.r.t. fading and loss due to formation of covalent modification etc.

--J

Actually, FRAP has to do with photobleaching. In FRAP you pulse an area with a high power laser, which effectively photobleaches the entire area. The recovery is not due to long lived triplet states recovering, but "fresh" fluorophores diffusing into the area of interest. This is the main purpose of FRAP, to calculate the diffusion coefficient.

And yes, there is some confusion on lifetime. Lifetime can either be taken to mean the average length of time that the fluorophore is in its excited state, or the time before the fluorophore will bleach. This is briefly mentioned in the main article. Hope that clears some things up. afireinside13t (talk) 14:50, 8 December 2009 (UTC)[reply]

WikiProject class rating[edit]

This article was automatically assessed because at least one WikiProject had rated the article as stub, and the rating on other projects was brought up to Stub class. BetacommandBot 22:03, 9 November 2007 (UTC)[reply]

Fluorescence only?[edit]

Does not the term photobleaching also apply to the more general loss of color / chromophores under the influence of light? For example, in the photobleaching of corals, or when carrying out UV-Visible transmission spectrophotometry? Robert Rossi (talk) 15:52, 25 October 2020 (UTC)[reply]

Photostability of quantum dots[edit]

My experience is that colloidal semiconductor quantum dots (at least some of the commercially available ones) are typically much, much more susceptible to fading than stated here. Where is the 10^8 number coming from? 198.21.199.201 (talk) 17:45, 9 June 2023 (UTC)[reply]