NER: Exploratory Research on Developing a Nanoscale Sensing Device for Measuring the Supply of Iron to Eukaryotic Phytoplankton in Natural Seawater

该提案是根据NSE， NSF-0019收到的。认识到铁在沿海海洋系统中潜在的关键作用的长期拖延在很大程度上是因为海水中微生物与铁相互作用的复杂性。目前还没有测定原核或真核浮游植物生物可利用铁的分析方法。然而，有证据表明，真核浮游植物的铁可利用性可以通过向沿海水域添加真菌铁铁细胞去铁胺B （DFB）来调节。DFB-Fe复合物不仅无法以显著的速率吸收，而且在海水中与天然有机配体类竞争铁。因此，在滴定系列中测量DFB-Fe浓度应提供浮游植物铁供应的一级测量。该项目将通过构建具有所需运输特性的脂质体，研究将现有的散装液膜系统小型化的可行性，该系统可以从水溶液中主动分离和浓缩59Fe-DFB。这些纳米器件的高表面积和最佳扩散方面将在沿海水域遇到的极低溶解铁浓度（1 nM）下实现59Fe-DFB的有效积累。这些纳米器件的传输特性将作为脂质体组成和制造条件的函数进行测量，以优化59Fe-DFB从海水基质中的主动传输。如果进展允许，这些纳米器件积累的59Fe与自然群体培养的细胞59Fe摄取和生长之间的关系将被探索。这个探索性项目的直接目标是证明开发纳米级传感器的可行性，用于量化沿海海水中真核浮游植物的铁供应。更广泛的目标是建立纳米技术在海洋领域传感生物活性基质的可行性。

This proposal was received in response to NSE, NSF-0019.The long delay in recognizing the potentially key role of Fe in coastal marine systems has been in large part because of the complexity of microbial:Fe interactions in seawater. There still is no analytical method for determining biologically available Fe for either prokaryotic or eukaryotic phytoplankton. However, there is evidence that Fe availability to eukaryotic phytoplankton can be regulated by additions of the fungal siderophore desferrioxamine B (DFB) to coastal waters. The DFB-Fe complex not only is unavailable for uptake at significant rates, but also outcompetes the natural organic ligand classes in seawater for Fe. Measurement of DFB-Fe concentrations in a titration series should therefore provide a first order measure of the Fe supply to phytoplankton.This project will investigate the feasibility of miniaturizing a current bulk liquid membrane system that can actively isolate and concentrate 59Fe-DFB from aqueous solutions by constructing liposomes with the needed transport characteristics. The high surface area and optimal diffusional aspects of these nanodevices will enable efficient 59Fe-DFB accumulations at the extremely low dissolved Fe concentrations (1 nM) encountered in coastal waters. The transport characteristics of these nanodevices will be measured as a function of liposome compositions and fabrication conditions to optimize the active transport of 59Fe-DFB from a seawater matrix. If progress permits, the relationship between 59Fe accumulated by these nanodevices and cellular 59Fe uptake and growth of natural population cultures will be explored. The immediate goal of this exploratory project is to demonstrate the feasibility of developing nanoscale sensors for quantifying the supply of Fe to eukaryotic phytoplankton in coastal seawaters. The broader goal is to establish the viability of nanotechnology for sensing bioactive substrates in the marine realm.