RUI: Effect of Multidentate Ligand Exchange Pathways on Metal Ion Uptake

化学系的环境化学科学项目资助了惠特曼学院的内森·博兰教授。博兰教授和他的学生研究影响生物体中金属离子可用性的化学反应。金属离子可以是必需的营养素或有毒污染物，这取决于身份和浓度。金属离子的化学形式影响金属被生物体吸收的容易程度。研究人员使用螯合树脂，这是合成化合物，也吸收金属离子，以估计生物利用度，特别是天然沃茨。该项目研究螯合树脂捕获被不同有机分子结合的金属离子的化学反应。该项目的目标是更好地了解这些反应，并建立更好的预测工具。该项目为本科生提供了一个独特的机会，作为研究人员，合作者和演讲和论文的共同作者参与。 该项目将使惠特曼的本科生沉浸在前沿的环境化学研究中。该项目将有助于惠特曼研究活跃的教师在环境化学和过渡金属化学的兴趣不断增长的网络。该项目将通过向他的课程提供该领域当前和相关问题，提高博兰博士整合教学和研究的能力。Boland博士致力于继续参与惠特曼的科学推广和教育活动，吸引当地中小学学生和教师。多齿配体交换反应在控制过渡金属离子形态和生物吸收方面非常重要。然而，对于反应途径如何影响反应动力学的机理理解有限。薄膜扩散梯度技术（DGT）的目的是模拟生物吸收，是一个有用的工具，用于评估金属离子的生物利用度在原位。该项目使用连续-半连接-分离框架对多齿配体交换反应进行分类，以评估DGT和biouptake模型中的常见假设。镍吸收到一套DGT螯合树脂层的初始速率在不同的反应条件下进行定量。结果被用来评估新的组合动力学传质模型为每个多齿配体交换途径。此外，该项目还评估了低分子量有机酸（如草酸盐）和常见组成离子钙对金属离子吸收速率和途径的影响。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

The Environmental Chemical Sciences Program in the Division of Chemistry funds Professor Nathan Boland at Whitman College. Professor Boland and his students study chemical reactions that affect the availability of metal ions in living organisms. Metal ions can be essential nutrients or toxic contaminants depending on identity and concentration. The chemical form of a metal ion affects how readily the metal is absorbed into an organism. Researchers use chelating resins, which are synthetic compounds that also absorb metal ions, to estimate bioavailability in particular natural waters. This project studies the chemical reactions where chelating resins capture metal ions bound by different organic molecules. The goal of this project is to better understand these reactions and build better predictive tools. The project provides a unique opportunity for undergraduate students to participate as researchers, collaborators, and co-authors of presentations and papers. The project will immerse Whitman undergraduate students in cutting-edge environmental chemistry research. The project will contribute to a growing network of research-active faculty at Whitman with interests in environmental chemistry and transition metal chemistry. This project will enhance Dr. Boland's ability to integrate teaching and research by informing his courses with current and relevant issues in the field. Dr. Boland is committed to continued involvement with Whitman-based science outreach and educational activities engaging local elementary and middle school students and teachers.Multidentate ligand exchange reactions are important in controlling transition metal ion speciation and biouptake. However, there is limited mechanistic understanding of how reaction pathways affect reaction kinetics. The technique of diffusive gradients in thin films (DGT) was designed to mimic bio-uptake and is a useful tool for evaluating metal ion bioavailability in situ. The project uses the adjunctive-semijunctive-disjunctive framework for classifying multidentate ligand exchange reactions to evaluate common assumptions in both DGT and biouptake models. Initial rates of nickel uptake into a suite of DGT chelating resin layers are quantified under varied reaction conditions. Results are used to evaluate new combined kinetic-mass transfer models for each multidentate ligand exchange pathway. Additionally, the project evaluates the effect of low molecular weight organic acids (e.g. oxalate) and the common constituent ion calcium on rates and pathways of metal ion uptake.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.