Collaborative Research: ISS: Biofilm Inhibition with Germicidal Light Side-Emitted from Nano-enabled Flexible Optical Fibers in Water Systems

细菌在几乎任何含有水的东西中以薄而粘稠的生物膜的形式生长在表面上。水中90%以上的微生物存在于生物膜中，相比之下，流动水中的微生物不到10%。生物膜可能通过携带病原体(如嗜肺军团菌)对水质产生不利影响，这些病原体可以释放回水中，或对水系统运行产生不利影响(例如，调节表面腐蚀、减少传热、阀门或传感器堵塞)。生物膜在医疗设备、工业制造和饮用水系统中存在并造成问题，包括宇航员所依赖的系统。例如，在国际空间站，生物膜的形成危及包括宇航服、水回收装置、散热器和导航窗在内的关键设备。控制生物膜的化学策略需要运输、储存和输入高强度的消毒液，这可能会带来其他问题。这个项目的目的是了解和演示如何使用纳米纤维将杀菌紫外线传递到可能生长生物膜的表面，这种纤维的作用就像“消毒荧光棒”。杀菌紫外线可以杀死任何附着在表面或生长在表面上的细菌。尽管同样类型的细菌在地球上和国际空间站的水系统中生长，但太空中的重力缺乏会影响细菌群落的生长方式，这提供了关键的见解。研究小组将在地球和国际空间站上进行平行实验，以了解紫外线是否会因为重力效应而对生物膜产生不同的影响。比较微重力和地球重力下的生物膜生长和对杀菌紫外线的反应，将增强我们创造健康人类栖息地的能力。研究小组将与高中生合作，通过一个由四部分组成的生物膜模块解释生物膜在日常生活中的作用。该模块将使用纳米技术实现的无化学消毒液进行开发。目前，生物膜对微重力下杀菌紫外线的敏感性尚不清楚。该项目涉及负责管理国际空间站国家实验室的机构--空间科学促进中心。实验将研究杀菌紫外线(265至285纳米)对水系统中生物膜的抑制作用，使用据报道存在于国际空间站水系统生物膜中的五种细菌。首先，国际空间站上的杀菌紫外线生物膜抑制实验将展示杀菌光对与国际空间站水系统所用材料相关的生物膜形成的影响。在极端环境(微重力)下，这种方法作为一种无化学物质、持续时间长的生物膜控制策略的可行性将与地球上其他相同的地面控制方法进行比较。了解微重力的影响很重要，因为与地球重力相比，一些细菌的生长和最终密度以及相关的生物膜形成在微重力下可能不同。其次，在装有侧面发射光纤的充水反应器中的实验将在地球重力下进行，以研究两种机制(光解和氧化)对减轻生物膜形成的影响。杀菌光是由无汞发光二极管产生的，这些发光二极管进入独特的纳米技术支持的光纤，这些光纤直接附着在表面并侧面发射紫外线。最先进的纳米材料、化学和生物方法和模型将被应用于生物膜的研究。将研究发光二极管运行的占空比，以减少功率需求，并相应地减少需要管理的热负荷，同时实现生物膜缓解。私人投资者将开发和应用定量聚合酶链式反应引物，以识别组成联合体的每一种细菌，以监测种群水平。此外，研究人员将应用荧光活性染色和共聚焦显微镜加上图像分析来评估紫外线照射下生物膜活性和结构的变化。更广泛的影响包括开发一个新的四部分生物膜模块，重点是通过纳米技术实现的无化学解决方案，该模块将与高中教师共同开发并用于公共宣传活动。该项目将促进对微重力环境中生物杀菌处理效率的基本理解，与地球相比，微重力环境中细菌的生长和生物膜的形成可能不同。比较微重力和地球重力下的生物膜生长和对UV-C光的响应将提高我们创造健康人类栖息地的能力。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。

Bacteria grow on surfaces as thin, slimy biofilms in nearly anything that contains water. Over 90% of microorganisms present in water exist within biofilms, compared to less than 10% in the flowing water. Biofilms can adversely impact water quality by harboring pathogens, such as Legionella pneumophila, that can be released back into water, or adversely impact water system operations (e.g., mediating surface corrosion, reducing heat transfer, clogging of valves or sensors). Biofilms exist and cause problems in medical devices, industrial manufacturing, and drinking water systems, including those upon which astronauts rely. For example, in the International Space Station, biofilm formation jeopardizes key equipment including spacesuits, water recycling units, radiators, and navigation windows. Chemical strategies to control biofilms require transport, storage and input of high-strength disinfecting solutions that may bring other problems. This project aims to understand and demonstrate how germicidal ultraviolet light delivered using nano fibers, which behave like “disinfecting glowsticks”, to surfaces where biofilms might grow. The germicidal ultraviolet light kills any bacteria that stick to or grow on a surface. Although the same types of bacteria grow on Earth and in the water systems on the International Space Station, the lack of gravity in space can influence how bacteria communities grow, providing key insights. The research team will conduct parallel experiments on Earth and on the International Space Station to understand if ultraviolet light influences biofilms differently because of gravity effects. Comparing biofilm growth and response to germicidal ultraviolet light in microgravity versus earth-gravity will enhance our ability to create healthy human habitats. The research team will work with high school students, explaining the roles of biofilms in everyday life through a four-part biofilm module. This module will be developed using chemical-free disinfection solutions enabled by nanotechnology.Currently, the sensitivity of biofilms to germicidal ultraviolet light in microgravity is unknown. This project involves the Center for the Advancement of Science in Space, the entity responsible for managing the International Space Station National Lab. Experiments will study effects of germicidal ultraviolet light (265 to 285 nanometers) on the inhibition of biofilms in water systems using five bacterial species that reportedly are present in biofilms in International Space Station water systems. First, the germicidal ultraviolet light biofilm inhibition experiments on the International Space Station will demonstrate impacts of germicidal light on biofilm formation on materials relevant to those used in International Space Station water systems. The feasibility of this approach as a chemical-free, long-duration biofilm control strategy in an extreme environment (microgravity) will be compared against otherwise identical ground controls on Earth. The influence of microgravity is important to understand since the growth and final density of some bacteria, and associated biofilm formation, can differ in microgravity, as compared to earth gravity. Second, experiments in a water-filled reactor equipped with side-emitting optical fibers decorated using different types of nanoparticles will be operated under earth-gravity to study the effects of two mechanisms (photolysis versus oxidation) to mitigate biofilm formation. Germicidal light is produced from mercury-free light emitting diodes, which enters unique nanotechnology enabled optical fibers that attach directly on surfaces and side-emit ultraviolet light. State of the art nanomaterial, chemical and biological methods and models will be applied to study biofilms. Duty-cycling of light emitting diode operation will be studied to reduce power requirements, and correspondingly the thermal load that requires management while achieving biofilm mitigation. The PIs will develop and apply quantitative polymerase chain reaction primers to identify each bacteria comprising the consortia for monitoring population levels. Additionally, the researchers will apply fluorescent viability stain with confocal microscopy plus image analysis to assess changes in biofilm viability and architecture upon ultraviolet light exposure. The broader impacts include developing a new four part biofilm module focusing on chemical free solutions enabled by nanotechnology, that will be co-developed and used with high school teachers and in public outreach activities. The project will advance the fundamental understanding of biocidal treatment efficiency in microgravity environments, where bacterial growth and biofilm formation can differ as compared to Earth. Comparing biofilm growth and response to UV-C light in microgravity versus earth-gravity will advance our ability to create healthy human habitats.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.