Ortega Richard, Bohic Sylvain, Tucoulou Rémi, Somogyi Andrea, Devès Guillaume
Chimie Nucléaire Analytique et Bioenvironnementale, CNRS/Université de Bordeaux 1, BP 120-33175 Gradignan cedex, France.
Anal Chem. 2004 Jan 15;76(2):309-14. doi: 10.1021/ac035037r.
Trace element imaging and speciation analysis in cells and subcellular compartments is a challenging and important objective for modern analytical chemistry in order to better understand the biological chemistry of essential and toxic elements. A focusing system based on Kirkpatrick-Baez design optics mounted on a synchrotron radiation scanning X-ray microscope has been developed at the ESRF and was used for trace element quantitative imaging in single cells. The focused microbeam (1.3 x 3.2 microm(2)) obtained in that way led to a photon flux as bright as 1.5 x 10(11) photons/s at 14 keV. The absolute detection limit of this analytical probe, as measured on standard reference materials, was shown to be 2 x 10(-)(17) g for most elements. Chemical maps of human carcinoma and of Saccharomyces cerevisiae cells were obtained for minor (P, S, Cl, K) and trace elements (Fe, Zn). Within human cancer cells, chemical elements are homogeneously distributed at the current spatial resolution and correlated with the sample's mass, except Fe, which shows micrometer-sized structures around the cell nucleus, and Zn, which slightly concentrates in the nucleus, while chemical maps of S. cerevisiae show homogeneous pattern distribution at the cellular level.
为了更好地理解必需元素和有毒元素的生物化学性质，对细胞和亚细胞区室中的微量元素成像和形态分析是现代分析化学中一项具有挑战性但又很重要的目标。欧洲同步辐射装置（ESRF）已开发出一种基于柯克帕特里克-贝兹设计光学元件的聚焦系统，该系统安装在同步辐射扫描X射线显微镜上，并用于单细胞中的微量元素定量成像。通过这种方式获得的聚焦微束（1.3×3.2微米²）在14 keV时产生的光子通量高达1.5×10¹¹光子/秒。在标准参考物质上测量，该分析探针的绝对检测限对大多数元素而言为2×10⁻¹⁷克。获得了人类癌细胞和酿酒酵母细胞中微量（磷、硫、氯、钾）和痕量元素（铁、锌）的化学图谱。在人类癌细胞内，除了铁在细胞核周围呈现微米级结构，锌在细胞核中略有富集外，在当前空间分辨率下化学元素均匀分布且与样品质量相关，而酿酒酵母的化学图谱在细胞水平上显示出均匀的模式分布。
