STABLE ISOTOPES AS BIOTRACERS BY NOVEL LASER METHODS

拟议研究的主要目标是：(A)设计和研究 简并四波混频(D4WM)激光光谱新方法 对生物示踪具有重要意义的稳定同位素的高分辨率测量 研究，(B)仔细比较这些方法与现有方法 方法，以及(C)有效性和有用性的论证 在使用真实生物医学样本的生物示踪研究中使用这些方法。 虽然许多同位素已被用于研究矿物质的吸收和 在人类的新陈代谢研究中，没有简单、常规的分析方法 稳定同位素富集度测量方法。目前可用 质谱仪或电感耦合等离子体质谱等方法的局限性包括 样品处理速度慢、成本高、同量异压或基质干扰 费时的样品提纯或修饰(络合)步骤。 安全可靠的生物示踪剂研究可以通过测量稳定的 使用D4WM在痕量浓度水平上的非放射性同位素。激光 D4WM提供出色的亚多普勒(和洛伦兹最小化)频谱 因此，它不仅可以分解同位素，而且还可以 单个同位素的超精细谱线。一种超精细的结构，原子 光谱指纹是唯一的，没有两个结构是完全相同的， 因此，它提供了明确的衡量标准。因此，光谱和 在这些高分辨率中，化学干扰问题可以忽略不计 研究，即使在样品中存在多种元素的混合物。 同位素比率可以通过简单地比较峰值强度来测量 许多分辨率良好且铺展开来的超精细结构。当超细时 构造错综复杂，仍可提取丰富的同位素信息 通过使用基于理论D4WM的谱反卷积方案 计算。稳定同位素和放射性同位素都可以测量。 同时，由于存在的所有类型的同位素都是以 超精细结构。与传统方法相比的一些优势 包括：极佳的灵敏度、选择性、重现性、相对 仪器价格低廉，操作简单安全，样品快速 吞吐量。这些新的激光方法的有效性和准确性 将对生物示踪剂中一些最重要的元素进行研究 同位素研究，如钙、铅、镁、铜、镍、银、铁、镉、锌、钯、Re、Os、 Li、Ba、Al和Rb，使用包括放电在内的不同雾化器， 石墨炉和火焰。仔细而详细的研究 这些基于激光的新方法的可靠性和有用性将是 对许多真实的生物样本执行，同时将它们与当前 可用于生物示踪剂研究的方法。PI将证明、比较和 论证了D4WM同位素分析方法的重要意义 替代方法如果不是安全、成本最有效的方法之一 有效、简单和明确的生物示踪剂研究，不使用 有害的放射性同位素。 该研究所还将研究测量圆二向色性的新激光方法。 在基于热或偏振光栅的D4WM的气相样品中 设置。光学活性手性的成功检测和分析 生物医学物质在微量浓度水平上有望实现许多 在各种生物医学领域的应用。

The main objectives of the proposed research are (a) design and study of new degenerate four-wave mixing (D4WM) laser spectroscopic methods in high-resolution measurement of stable isotopes important for biotracer studies, (b) careful comparison of these methods with currently available methods, and (c) the demonstration of the effectiveness and the usefulness of these methods in biotracer studies using real biomedical samples. Although many isotopes have been used in studying mineral absorption and metabolism in human subjects, there is no simple, routine analytical method for measurement of stable isotope enrichment. Currently available methods such as mass spectrometry or ICP-MS have limitations including slow sample throughput, high cost, isobaric or matrix interferences, and time-consuming sample purification or modification (chelation) steps. Safe and reliable biotracer studies can be performed by measuring stable non-radioactive isotopes at trace-concentration levels using D4WM. Laser D4WM offers excellent sub-Doppler (and Lorentzian minimized) spectral resolution, and hence, it can resolve not only isotopes, but also hyperfine lines of individual isotopes. A hyperfine structure, the atomic spectroscopic fingerprint, is unique and no two structures are identical, and hence, it offers unambiguous measurements. Hence, spectral and chemical interference problems are negligible in these high-resolution studies, even when a mixture of many elements is present in the sample. Isotope ratios can be measured by simply comparing the peak intensities in many well-resolved and spread-out hyperfine structures. when hyperfine structures are convoluted, rich isotope information can still be extracted by using spectral deconvolution schemes based on theoretical D4WM calculations. Both stable and radioactive isotopes can be measured simultaneously, since all types of isotopes present are measured in a hyperfine structure. Some of the advantages over conventional methods include: excellent sensitivity, selectivity, reproducibility, relatively inexpensive instrumentation, simple and safe operation, and fast sample throughput. The effectiveness and the accuracy of these new laser methods will be investigated for some of the most important elements in biotracer isotope studies, such as Ca, Pb, Mg, Cu, Ni, Ag, Fe, Cd, Zn, Pd, Re, Os, Li, Ba, Al, and Rb, using different atomizers including discharge, graphite furnace and flame. Careful and detailed studies on the reliability and the usefulness of these new laser-based methods will be performed for many real biosamples while comparing them to currently available methods for biotracer studies. The PI will prove, compare and demonstrate that the D4WM isotope analysis method is an important alternative method if not one of the most effective methods for safe, cost effective, simple and unambiguous biotracer studies, without the use of undesirable radioactive isotopes. The PI will also study new laser methods for measuring circular dichroism in the gas-phase samples using thermal or polarization-grating based D4WM setups. Successful detection and analysis of optically active chiral biomedical substances at trace-concentration levels promise many applications in various biomedical areas.