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

化学学部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内金属离子可用性的化学反应。金属离子可以是必需的营养物质，也可以是有毒的污染物，这取决于其身份和浓度。金属离子的化学形态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（一种也能吸收金属离子的合成化合物）来估计特定天然水域的生物利用度。本项目研究螯合树脂捕获由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理解这些反应，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，以研究人员、合作者和报告和论文的共同作者的身份参与其中。该项目将使惠特曼大学的本科生沉浸在前沿的环境化学研究中。该项目将为惠特曼大学不断增长的研究活跃的教师网络做出贡献，他们对环境化学和过渡金属化学感兴趣。这个项目将通过向他的课程介绍该领域的当前和相关问题，提高Boland博士整合教学和研究的能力。博兰博士致力于继续参与以惠特曼为基础的科学推广和教育活动，吸引当地的中小学生和教师。多齿配体交换反应在控制过渡金属离子形成和生物吸收方面具有重要意义。然而，对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（DGT）技术是一种模拟生物吸收的技术，是评价金属离子原位生物利用度的有效工具。该项目使用辅助-半结合-析取框架对多齿配体交换反应进行分类，以评估DGT和生物吸收模型中的常见假设。在不同的反应条件下，测定了一套DGT螯合树脂层对镍的初始吸收速率。研究结果用于评估每个多齿配体交换途径的新的联合动力学-质量传递模型。此外，该项目还评估了低分子量有机酸（如草酸）和常见成分钙离子对金属离子吸收速率和途径的影响。该奖项反映了美国国家科学基金会的法定使命，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.