Collaborative Research: Development of a next generation sensor for measuring biologically available iron in seawater

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There is increasing evidence that iron is important not only in the regulation of bulk phytoplankton production in large regions of the world oceans, but that it also profoundly influences the speciation of algae within the phytoplankton assemblage. The broad implications resulting from these dual effects range from impacts on the global carbon cycle to the possible stimulation of harmful algal blooms. There is a strong need for ultra-sensitive, real-time monitoring and detection technologies that capture the reactive iron pool in seawater that is available to eukaryotic phytoplankton.The PI?s request funding to ?biocalibrate? the reactive iron fraction to gain a measure of iron availability to marine eukaryotic phytoplankton. The PI?s will combine Time Resolved Fluorescence (TRF) and Fluorescence Resonate Energy Transfer (FRET) to develop an ultra-sensitive photoactive nanodevice that uses the siderophore desferrioxamine B (DFB) as the iron-selective sensor interface, lanthanide fluorescence to report the presence of iron in this receptor, and Q-dot nanocrystals to greatly amplify this signal to achieve the picomolar level sensitivity needed to study both coastal and offshore ocean watersThe sensor will be calibrated with a range of nearshore and offshore species of cyanobacteria, diatoms and dinoflagellates, and the coccolithophorid Emiliania huxleyi; phytoplankton important in the regulation of carbon export from surface to the deep ocean. The ultimate goal of the project is to develop a photoactive nanosensor that allows real-time in situ measurements that reflect phytoplankton growth rates.Broader Impacts: The development of new generation of sensor to measure labile iron in-situ will greatly advance our knowledge of iron biogeochemistry. In addition, due to extremely short response time, this sensor will provide a unique opportunity to measure iron kinetics, cycling which is one of the biggest challenge in this research area, believe to be critical to control iron bioavailability to phytoplankton. Therefore this project will certainly lead to the burgeoning of this research area, potentially leading to new findings. In addition to supporting graduate students and undergrads, this proposal involves middle school teachers. Orcutt has obviously established productive relationships with local educators, and the letters from these teachers outlining their enthusiasm for continuing the relationship gives confidence that the proposed work will lead to an effective educational outcome. The potential for involvement of minority students at Southern Miss. is also significant. The proposed work also has the benefit of ?fertilizing? the field of oceanography with advances in other sciences (chemistry, materials).