Melanin Radicals in Paraffin-embedded Melanoma Investigated Using Surface-type Dielectric Resonator for X-band EPR

作者：Nakagawa Kouichi^*; Minakawa Satoko; Sawamura Daisuke

来源：Analytical Sciences, 2018, 34(7): 837-840.

DOI：10.2116/analsci.18P055

• EPR
• surface detection
• dielectric resonator
• melanin radical
• melanoma

We investigated melanin radicals in paraffin-embedded malignant melanoma (MM) using a surface-type dielectric resonator for X-band electron paramagnetic resonance (EPR) and analyzed the radical species. The surface-type resonator's performance was examined using 5 - 10 mu L of 0.1 mM 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPOL) aqueous solution in a 1.0-mm (i.d.) glass capillary as well as 1,1-dipheny1-2-picrylhydrazyl (DPPH) powder. The surface-type detection has approximately two times poorer SIN ratio than commercial insertion-type detection. A sample of the paraffin-embedded MM specimen was used for the radical detection. We obtained an EPR spectrum of melanin radicals in the paraffin-embedded melanoma sample (size similar to 3 x 4 x 3 mm). A single line (similar to 0.64 mT peak-to-peak line-width) with a small shoulder was observed and was identified as a pheomelanin-related radical. The pheomelanin radical can be directly related to the MM. Thus, the present results were a good indication for noninvasive measurement, as well as for detailed analyses of melanin radicals in human MM.

• 出版日期2018-7