NIRT: Developing a Nanoscale Sensing Device for Measuring the Supply of Iron to Phytoplankton in Marine Systems

建议活动的智力价值：这项建议是根据NSE NSF-02-148收到的。越来越多的证据表明，铁在海洋生态系统中具有独特的作用，既调节世界高硝酸盐、低叶绿素地区的浮游植物总产量，也影响在其他地区发现的浮游植物群落的主要组成。值得注意的是，对于如何定义生物可利用铁，而不是大量营养素氮、磷或硅，人们没有达成一致意见。目前对海洋生态系统将如何影响气候变化幅度的预测性洞察在很大程度上受到这个问题的阻碍，以及关于海洋中铁分布的数据极度匮乏。最近有证据表明，在散装海水培养中，可以通过少量添加真菌铁载体去铁肟B(DFB)来调节铁的利用率。铁-DFB络合物不容易被真核浮游植物利用，因此如果测量DFB络合的铁的量并将其校准为浮游植物对铁的吸收，就可以得到一个新的铁有效性的一级衡量标准。在我们目前研究的基础上，我们已经开发出专门从溶液中获得DFB结合铁的脂质体。这些直径为100纳米的设备为应用纳米技术在海洋水域创造新型铁生物传感器开辟了道路。该项目的目标是1)通过提高这些纳米设备的物理稳定性，确定其大小/功能关系，并检查其他DFB-Fe转运体分子的有效性，来优化这些纳米设备，2)开发自我报告能力，以量化这些纳米设备对铁的吸收，以及3)校准这些纳米设备对铁的捕获与各种浮游植物对铁的吸收。预期的最终产品将是一种经过校准的纳米级生物传感器，用于实验室规模，然后可以改装成部署在远程车辆上。拟议活动产生的更广泛影响：参与该项目的两个机构(缅因州大学和科尔比学院)在让本科生和研究生参与海洋科学和化学前沿研究方面有着良好的记录，该项目将继续这一进程。

0304523WellsIntellectual Merit of the Proposed Activity: This proposal was received in response to NSE NSF-02-148.There is increasing evidence that Fe has a singularly unique role in marine ecosystems, both regulating total phytoplankton production in high nitrate, low chlorophyll regions of the world, and influencing the predominant composition of the phytoplankton assemblages found in others. It is remarkable then that there is no agreement about how to define biologically available Fe, in contrast to the macronutrients nitrogen, phosphorous or silicon. Current attempts to attain predictive insights to how ocean ecosystems will influence the magnitude of climate change are blocked in large part by this question, along with an extreme shortage of data on Fe distributions in the oceans. There is recent evidence that Fe availability can be regulated in bulk seawater incubations by small additions of the fungal siderophore desferrioximine B (DFB). The Fe-DFB complex is not readily available to eukaryotic phytoplankton, so that if the quantity of Fe complexed by DFB were measured and calibrated to Fe uptake by phytoplankton it could yield a novel first order measure of Fe availability. Building from our current research we have developed liposomes that specifically acquire DFB-bound Fe from solution. These devices, 100 nm in diameter, open the way to applying nanotechnology to create a new breed of Fe biosensors in marine waters. The project goals are to 1) optimize these nanodevices by improving their physical robustness, identifying the size/functionality relationship, and examining the efficacy of other DFB-Fe transporter molecules, 2) develop self-reporting capabilities for quantifying Fe uptake by these nanodevices, and 3) to calibrate the capture of Fe by these nanodevices to the Fe uptake by various phytoplankton species. The anticipated final product will be a calibrated nanoscale biosensor for laboratory-scale use that could then be adapted for deploying on remote vehicles. Broader Impacts Resulting from the Proposed Activity: The two institutions involved in this project (U. Maine and Colby College) have a strong track record for involving undergraduate and graduate students in cutting edge research in marine science and chemistry, and this project will continue this process.