NATURE OF ESR SIGNAL IN MELANINS: A HIGH FIELD-HIGH FREQUENCY CW-ESR STUDY

黑色素中 ESR 信号的性质：高场高频 CW-ESR 研究

• 批准号: 8172148
• 负责人: TADEUSZ SARNA
• 金额: $ 2.99万
• 依托单位: CORNELL UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-09-01 至 2011-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8172148
• 关键词: Acids; Behavior; Cells; Chemicals; Computer Retrieval of Information on Scientific Projects Database; Cytoplasmic Granules; Electric Conductivity; Exhibits; Exposure to; Eye; Frequencies; Funding; Goals; Grant; Hair; Human; In Situ; Institution; Investigation; Light; Measurement; Medical; Melanins; Modality; Molecular; Nature; Oxidative Stress; Physiologic pulse; Pigmentation physiologic function; Pigments; Property; Research; Research Personnel; Resolution; Resources; Signal Transduction; Skin; Sodium; Sodium Chloride; Source; Structure; Structure of retinal pigment epithelium; System; Uncertainty; United States National Institutes of Health; age related; design; eumelanin; interest; oxidation; pheomelanin; physical model; physical property; semiquinone radicals

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Melanin is a key component of the human pigmentary system. The degree of pigmentation of the human skin, eyes or hair is to a large extent determined by the ability of cells to synthesize eumelanin and pheomelanin. The various functions of the melanins are defined by their chemical and physical properties. These properties in turn are defined by the molecular, supermolecular and aggregate-level structures. The ultimate goal is to construct a consistent model of these physical effects in order to engender understanding of how molecular and cellular scale structures relate to macroscopically observable properties and functions of melanins aiding the design of appropriate medical treatment modalities. Most natural melanin pigments exhibit a single, slightly asymmetric ESR signal at X-band that contains very little structural information. Preliminary W-band cw-ESR measurements of natural melanin granules, isolated from human retinal pigment epithelium, indicate distinct changes of the ESR spectrum that suggest possible age-dependent in situ photo oxidation of the ocular melanin. Our aim is to use even higher ESR frequencies/fields to spectrally resolve these small physicochemical changes of ocular melanin that may result from integrated exposure to light and oxidative stress. Our initial cw study is at 170/240 GHz concentrated on synthetic melanin (Sigma Aldrich). Notably, the major spectral features are very similar to that of humic acid. We found that the spectrum of the sodium salt of humic acid (Sigma-Aldrich) at 241 GHz/9T has to within experimental uncertainty the same linewidth and g-factor as observed for synthetic melanin. The interesting question is the origin of the subtle, narrow features contained in the broad single line of the synthetic melanin. Since melanins are known for their unusual electric conductivity behavior, it is possible that the presence of the narrow line in the spectrum of synthetic melanin demonstrates correlations between semiquinone radicals (abundant in melanin). Further multifrequency HFHF ESR, due to its superior g-factor resolution, and pulse ESR investigation will help to distinguish and separate between the two broad and narrow components of the spectrum and refine their interpretation.

这个子项目是许多研究子项目中的一个 由NIH/NCRR资助的中心赠款提供的资源。子项目和 研究者（PI）可能从另一个NIH来源获得了主要资金， 因此可以在其他CRISP条目中表示。所列机构为 研究中心，而研究中心不一定是研究者所在的机构。 黑色素是人类色素系统的关键成分。人类皮肤、眼睛或头发的色素沉着程度在很大程度上取决于细胞合成真黑素和褐黑素的能力。黑色素的各种功能由其化学和物理性质定义。这些性质依次由分子、超分子和聚集体水平的结构定义。最终目标是构建这些物理效应的一致模型，以便理解分子和细胞尺度结构如何与黑色素的宏观可观察性质和功能相关，从而帮助设计适当的医学治疗方式。 大多数天然黑色素在X波段表现出单一的、略微不对称的ESR信号，其中包含的结构信息很少。 初步的W-波段CW-ESR测量的天然黑色素颗粒，从人类视网膜色素上皮细胞分离，表明不同的变化的ESR光谱，这表明可能的年龄依赖性原位光氧化的眼黑色素。我们的目标是使用更高的ESR频率/场来光谱解析这些可能由综合暴露于光和氧化应激引起的眼部黑色素的小的物理化学变化。 我们最初的cw研究是在170/240 GHz下集中于合成黑色素（Sigma Aldrich）。 值得注意的是，主要光谱特征与腐殖酸非常相似。我们发现，腐殖酸钠盐（Sigma-Aldrich）在241 GHz/9 T下的光谱必须在实验不确定度内具有与合成黑色素所观察到的相同的线宽和g因子。 有趣的问题是，合成黑色素的宽单线中包含的微妙、狭窄的特征的起源。 由于黑色素以其不寻常的导电行为而闻名，因此合成黑色素光谱中窄线的存在可能表明半醌自由基（黑色素中丰富）之间的相关性。 进一步的多频HFHF ESR，由于其上级g-因子分辨率，和脉冲ESR研究将有助于区分和分离光谱的两个宽和窄分量，并完善其解释。