OCE-PRF: Lighting up the ocean: resonant nanophotonic metasurfaces for autonomous in situ measurement of aquatic phycotoxins

OCE-PRF：照亮海洋：共振纳米光子超表面用于水生生物毒素的自主原位测量气候变化正在推动海洋和淡水生态系统的根本转变。浮游植物是一种微生物，负责全球一半的光合作用固碳和至少一半的世界氧气生产。然而，某些种类的浮游植物可以产生强大的生物毒素，危害人类和野生动物，污染水源，破坏当地经济。浮游植物毒素产生传感器是推进基础研究和气候适应能力所需的关键基础设施。然而，目前研究浮游植物毒素及其基因的方法是基于昂贵的方法，需要复杂的基础设施，并且缺乏对理解耦合水/气候生态系统动力学至关重要的远程实时检测能力。该项目通过开发一种新的光学测量技术来解决这一问题，该技术使用纳米结构硅表面来放大光以灵敏地检测目标分子。该项目将支持博士后研究人员，包括主要本科院校的本科生培训，并寻求为更好的资源管理和公共水资源管理贡献关键资源和数据。微观光合生物，浮游植物，是地球碳循环的重要组成部分，对推动生物地球化学循环至关重要。但在某些条件下，浮游植物可以经历爆炸性的生长，形成密集的藻华，称为有害藻华（HABs），可以覆盖数百平方公里，并产生强大的生物毒素。了解环境驱动因素如何影响浮游生物养分循环和毒素产生是提高气候适应能力的关键，但仍然是一个突出的测量挑战。监测有害藻华和了解毒素动态的方法主要基于显微镜、质谱和PCR；这些技术耗时，需要复杂的基础设施，并且缺乏必要的实时原位检测能力，以了解物理化学环境如何在不断变化的生态系统中驱动浮游植物的代谢动力学。该博士后奖学金旨在通过开发高质量因子（高q）纳米光子学来解决这一空白，该光子学用于近实时和原位的水生藻毒素敏感，定量，无扩增和无标签检测。高q超表面不是通过放大生物分子来成功检测它，而是使用纳米结构硅来强烈放大分子结合位点的激光，从而在一个可扩展的、高度复用的、紧凑的全光平台上对目标分子进行敏感检测。该博士后奖学金将重点研究两种藻毒素：软骨藻酸，一种由海洋硅藻产生的神经毒素，伪尼茨氏藻属，导致人类和野生动物死亡；微囊藻毒素，一种由蓝藻产生的肝脏毒素，对饮用、娱乐和农业用水供应构成重大威胁。软骨藻酸是一种低分子量的L-脯氨酸衍生物，而微囊藻毒素是一种相对较大的环肽；这两种普遍存在的藻毒素将共同证明该技术在海洋代谢物和不同环境中的广泛适用性。总之，这项研究将使在大范围浓度和环境条件下实时定量检测藻毒素成为可能。这项工作的结果将为藻毒素的实时测量提供一条途径，这些数据可以与温度、pH值和叶绿素荧光的相关测量相结合，并在此背景下进行解释，从而加深我们对气候条件变化如何驱动浮游植物生产力和毒素产生的基本理解。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。

OCE-PRF: Lighting up the Ocean: resonant nanophotonic metasurfaces for autonomous in situ measurement of aquatic biotoxins The changing climate is driving fundamental shifts in marine and freshwater ecosystems. Phytoplankton are microscopic organisms responsible for half of the global photosynthetic carbon fixation and at least half of the world’s oxygen production. However, certain kinds of phytoplankton can produce powerful biotoxins that harm humans and wildlife, contaminate water sources, and damage local economies. Sensors for phytoplankton toxin production are a critical infrastructure needed to advance both fundamental research and climate resilience. However, current methods of studying phytoplankton toxins and their genes are based on methods that are costly, require sophisticated infrastructure, and lack remote, real-time detection capabilities central to understanding the dynamics of the coupled water/climate ecosystem. This project addresses this gap by developing a new optical measurement technique that uses nanostructured silicon surfaces to amplify light for sensitive detection of target molecules. This project will support the postdoctoral research fellow, includes training of undergraduates from primarily undergraduate institutions, and seeks to contribute key resources and data for better resource management and public water stewardship.Microscopic photosynthetic organisms, phytoplankton, are an essential part of the earth’s carbon cycle and are critical to driving biogeochemical cycles. But under certain conditions, phytoplankton can undergo explosive growth forming dense blooms called harmful algal blooms (HABs) that can cover hundreds of square kilometers and produce powerful biotoxins. Understanding how environmental drivers impact plankton nutrient cycling and toxin production is key to advancing climate resilience but remains an outstanding measurement challenge. Methods of monitoring HABs and understanding toxin dynamics are largely based on microscopy, mass spectroscopy, and PCR; techniques that are time consuming, require sophisticated infrastructure, and lack the real-time in situ detection capabilities necessary to understand how the physicochemical environment drives phytoplankton metabolic dynamics in a changing ecosystem. This postdoctoral fellowship aims to address this gap by developing high quality factor (high-Q) nanophotonics for sensitive, quantitative, amplification-free, and label-free detection of aquatic phycotoxins in near real-time and in situ. Rather than amplifying a biomolecule to successfully detect it, high-Q metasurfaces use nanostructured silicon to strongly amplify laser light at molecular binding sites to enable sensitive detection of target molecules in a scalable, highly multiplexed, all-optical platform with a compact footprint. This postdoctoral fellowship will focus on two phycotoxins: domoic acid, a neurotoxin produced by the marine diatoms, Pseudo-nitzschia spp., that is responsible for human and wildlife mortalities, and microcystin, a liver toxin produced by cyanobacteria and that poses a major threat to drinking, recreational, and agricultural water supplies. While domoic acid is a low molecular weight L- proline derivative, microcystin is a relatively large cyclic peptide; together these two prevalent phycotoxins will demonstrate the broad applicability of this technique across marine metabolites and diverse environments. Together, this research will enable real-time quantitative detection of phycotoxins over a large range of concentrations and environmental conditions. The outputs of this work will be an avenue for real-time measurements of phycotoxins, which can be combined with and interpreted in the context of correlative measurements of temperature, pH, and chlorophyll fluorescence, deepening our fundamental understanding of how changing climate conditions drive phytoplankton productivity and toxin production.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.