Electron paramagnetic resonance (EPR) study of DOPA–melanin complexes with kanamycin and copper(II) ions

Lidia Najder-Kozdrowska,Andrzej B Wi&Eogon;Ckowski,Barbara Pilawa,Dorota Wrzesniok,Ewa Buszman

doi:10.1155/2011/353059

Lidia Najder-Kozdrowska, Andrzej B Wi&Eogon;Ckowski + Show 3 more

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https://doi.org/10.1155/2011/353059

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Abstract

This work comprises the study of DOPA–melanin complexes with kanamycin and copper(II) ions made by electron paramagnetic resonance EPR spectroscopy. The high concentration of paramagnetic centers in melanin makes the use of EPR spectroscopy possible. The unpaired electron localized on the oxygen atom in indol-5,6-quinone groups is the paramagnetic centers in this polymer. The aim of this work was the analysis of EPR parameters of recorded spectra. For researches were prepared melanin complexes which differed in complexing order of drug and Cu(II) ions, and in concentration of CuCl2solutions used during synthesis. The introduction of drugs and metal ions into melanin causes changes in EPR parameters of recorded spectra. Kanamycin causes the increase and copper(II) ions the decrease of concentrations of paramagnetic centres in melanin. Shape of EPR signal of DOPA–melanin was analyzed by fitting method. Results indicate that EPR line of DOPA–melanin is superposition of Gaussian and Lorentzian function.

Highlights

Electron paramagnetic resonance (EPR) is a very useful method for the study of melanin polymer [9,13,16,19]
The EPR signal of DOPA–melanin was recorded at low value of microwave power for avoidable of saturation phenomenon
The fitting by Gaussian and Lorentzian function shows that shape of EPR signal of DOPA–melanin cannot be described by these function (Figs 2–3) what is according to work [3]

Summary

Introduction

Electron paramagnetic resonance (EPR) is a very useful method for the study of melanin polymer [9,13,16,19]. Melanin contents a high concentration of paramagnetic centers. The unpaired electrons localized on the oxygen atoms in indol-5,6-quinone groups have the spin value S = 1 which obeys Curie law. Using the EPR method the existence of paramagnetic centres in thermally excited triplet state (S = 1) was proved [8]. Paramagnetic centers with spin S = 1 does not fulfil the Curie law. EPR method provides information on spin–spin and spin–lattice interactions in a sample. This polymer gives a colour for skin, ears and hair.

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