Al Khatib Maher, Costa Jessica, Baratto Maria Camilla, Basosi Riccardo, Pogni Rebecca
Department of Biotechnology, Chemistry and Pharmacy, Università degli Studi di Siena, Via A. Moro 2, 53100 Siena, Italy.
J Phys Chem B. 2020 Mar 19;124(11):2110-2115. doi: 10.1021/acs.jpcb.9b11785. Epub 2020 Mar 10.
Spectroscopical characterization of melanins is a prior requirement for the efficient tailoring of their radical scavenging, ultraviolet-visible radiation absorption, metal chelation, and natural pigment properties. Electron paramagnetic resonance (EPR), exploiting the common persistent paramagnetism of melanins, represents the elective standard for the structural and dynamical characterization of their constituting radical species. Although melanins are mainly investigated using X-band (9.5 GHz) continuous wave (CW)-EPR, an integration with the application of Q-band (34 GHz) in CW and pulse EPR for the discrimination of melanin pigments of different compositions is presented here. The longitudinal relaxation times measured highlight faster relaxation rates for cysteinyldopa melanin, compared to those of the most common dopa melanin pigment, suggesting pulse EPR spin-lattice relaxation time measurements as a complementary tool for characterization of pigments of interest for biomimetic materials engineering.
黑色素的光谱表征是有效调整其自由基清除、紫外-可见辐射吸收、金属螯合和天然色素特性的前提条件。电子顺磁共振（EPR）利用黑色素常见的持久顺磁性，是其构成自由基物种的结构和动力学表征的首选标准。尽管黑色素主要使用X波段（9.5 GHz）连续波（CW）-EPR进行研究，但本文介绍了将Q波段（34 GHz）应用于CW和脉冲EPR，以区分不同组成的黑色素色素。所测得的纵向弛豫时间表明，与最常见的多巴黑色素色素相比，半胱氨酰多巴黑色素的弛豫速率更快，这表明脉冲EPR自旋晶格弛豫时间测量可作为一种补充工具，用于表征仿生材料工程中感兴趣的色素。
