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

OCE-PRF：照亮海洋：用于原位自主测量水生生物毒素的共振纳米光子变表面气候变化正在推动海洋和淡水生态系统的根本性转变。浮游植物是负责全球一半的光合作用碳固定和至少一半的氧气生产的微生物。然而，某些种类的浮游植物可以产生强大的生物毒素，对人类和野生动物造成伤害，污染水源，损害当地经济。浮游植物毒素产生的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所基于的方法成本高昂，需要复杂的基础设施，而且缺乏远程实时检测能力，对于了解耦合的水/气候生态系统的动态至关重要。该项目通过开发一种新的光学测量技术来解决这一差距，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员，包括对主要是本科生机构的本科生的培训，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。微型光合作用生物，即浮游植物，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，浮游植物会经历爆炸性增长，形成被称为有害藻华(HABS)的密集水华，面积可达数百平方公里，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营养循环和毒素生产是提高气候适应能力的关键，但仍是一个突出的测量挑战。监测赤潮和了解毒素动态的方法主要基于显微镜、质谱学和聚合酶链式反应；这些技术耗时长，需要复杂的基础设施，并且缺乏了解物理化学环境如何推动不断变化的生态系统中浮游植物代谢动力学所需的实时原位检测能力。这一博士后奖学金旨在通过开发高质量因子(高Q)纳米光子学来弥补这一差距，该纳米光子学用于近实时和原位灵敏、定量、无放大和无标签的水生藻毒素检测。与放大生物分子以成功检测生物分子不同，高Q亚表面使用纳米结构硅在分子结合部位强烈放大激光，从而能够在占地面积紧凑的可扩展、高度多路复用的全光平台中对目标分子进行灵敏检测。这一博士后研究重点将集中在两种藻毒素上：软骨藻酸，一种由海洋硅藻产生的神经毒素，伪菱形藻，导致人类和野生动物死亡；以及微囊藻毒素，一种由蓝藻产生的肝脏毒素，对饮用水、娱乐和农业用水供应构成重大威胁。软骨藻酸是一种低相对分子质量的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展示这项技术在海洋代谢物和不同环境中的广泛适用性。总而言之，这项研究将能够在大范围的浓度和环境条件下实时定量检测藻毒素。这项工作的结果将是一条实时测量藻毒素的途径，可以在温度、pH和叶绿素荧光的相关测量的背景下结合和解释，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生产的基本理解。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势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.