Time-resolved EPR investigation of oxygen and temperature effects on synthetic eumelanin. Issue 3 (2010)

• Record Type: Journal Article
• Authors: Conti Conti, Fosca Fosca; Panzella Panzella, Lucia Lucia; Napolitano Napolitano, Alessandra Alessandra; d᾽Ischia d᾽Ischia, Marco Marco; Toffoletti Toffoletti, Antonio Antonio
• Is Part Of: Spectroscopy. Volume 24:Issue 3/4(2010)
• Page Start: 289
• Page End: 295
• Publication Date: 2010
• Subjects: Melanin -- DHICA -- EPR spectroscopy -- radical pair -- spin polarization -- excited state -- superoxide radical anion
• DOI: 10.3233/SPE-2010-0430
• Languages: English
• ISSNs: 0712-4813

Abstract

Abstract : Synthetic eumelanin produced using 5, 6-dihydroxyindole-2-carboxylic acid as precursor and H2 O2 /horseradish peroxidase as oxidative reagent, in form of dry powder, has been investigated under photoexcitation by TR-EPR spectroscopy. The formation of spin polarized radical pairs from triplet excited states of melanin has been observed both in absence and in presence of oxygen and has been followed as a function of the temperature in the range 140–290 K. The triplet mechanism explains the observed polarization pattern in net emission. In the presence of oxygen new radical pairs are formed by interaction of melanin with molecular oxygen.