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Elementary processes in the eosin-sensitized photooxidation of 3,3′-diaminobenzidine for correlative fluorescence and electron microscopy

Paper ID Volume ID Publish Year Pages File Format Full-Text
27344 44017 2011 6 PDF Available
Title
Elementary processes in the eosin-sensitized photooxidation of 3,3′-diaminobenzidine for correlative fluorescence and electron microscopy
Abstract

The sensitized photopolymerization of 3,3′-diaminobenzidine tetrahydrochloride (DAB) to yield a localized electron-dense precipitate is the basis of a correlative imaging technique, in which fluorescence and transmission electron microscopies are applied to dye-labeled biological samples. In the present work, the eosin (Eo) sensitized photooxidation of DAB has been investigated, as a model system for understanding the complex photochemical mechanism of this imaging process. It was observed that the irradiation with visible light (515 nm) of aqueous solutions of DAB plus Eo triggers a fast photoreaction of DAB, a parallel consumption of dissolved oxygen, and the formation of an optically dense polymer. Time-resolved spectroscopic measurements as a function of solution composition were used to analyze the initial reactive steps of the photoreaction, which are mediated by the Eo lowest excited triplet state (3Eo*). From all these experiments it was concluded that singlet molecular oxygen [O2(1Δg)], produced by the well-known 3Eo* plus O2 reaction, and superoxide radical anion (O2−) are the dominant reactant species in the photoprecipitation reaction. In contrast, in the absence of dissolved oxygen the rate of the photoreaction is only a 15% of the rate determined under aerobic conditions.

► Irradiation with visible light of aqueous solutions of DAB plus Eo triggers a fast photoreaction of DAB. ► The photopolymerization of DAB produces a consumption of dissolved oxygen. ► Singlet molecular oxygen and superoxide radical anion are the dominant reactant species in the photoprecipitation reaction.

Keywords
Diaminobenzidine; Eosin; Photooxidation; Singlet molecular oxygen; Superoxide radical anion
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Elementary processes in the eosin-sensitized photooxidation of 3,3′-diaminobenzidine for correlative fluorescence and electron microscopy
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Publisher
Database: Elsevier - ScienceDirect
Journal: Journal of Photochemistry and Photobiology A: Chemistry - Volume 220, Issue 1, 30 April 2011, Pages 25–30
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us