Adhesion and Resuspension of Biological Particulate Matter in Early-Childhood Indoor Microenvironments

婴幼儿90%以上的时间是在室内度过的，因此在室内环境中暴露于多种病原体。室内灰尘富含多种多样的微生物和过敏原。生命早期吸入暴露于室内粉尘的微生物和致敏成分，可在哮喘和过敏性疾病的发展和预防中发挥重要作用。当婴儿爬行、玩耍和学习走路时，他们会从尘埃中激起（重新悬浮）生物颗粒物质（bioPM：细菌、真菌、花粉）的浓云。室内bioPM的再悬浮和粘附特性仍然很差。在人类免疫发育的这一关键时期，需要新的研究来揭示控制bioPM暴露的潜在运输机制。该项目的目标是明确阐明在儿童早期微环境中控制生物膜粘附、再悬浮和空气传播的基本机制。暴露将使用一种新型机器人来确定，该机器人设计用于模拟婴儿在室内环境中的运动和暴露于bioPM。这项研究有可能改变我们对婴儿在其发育的关键阶段暴露于bioPM的理解。通过机械框架，该项目将对复杂的粘附和人为驱动的再悬浮过程的基本理解做出重大贡献，这些过程控制着室内环境中沉降尘埃的排放、空气运输和生物膜的命运。具体目标是：1)通过原子力显微镜研究生物膜与室内表面的粘附相互作用，探索生物膜的形态、疏水性、电荷和湿度对粘附力的影响；2)开发一种新型机器人平台，通过Purdue Miller儿童发展实验室学校（MCDLS）收集的生物识别数据来模拟婴儿/幼儿的运动，并研究空气动力学、振动和静电bioPM去除力；3)通过机器人的室内实验，发现婴儿/幼儿的运动如何使bioPM重悬，并建立物质平衡模型来预测bioPM的命运和运输。这项研究将为生物膜的物理化学性质如何影响室内表面的附着力创造新的知识。这是第一次，由婴儿特有的运动形式引起的bioPM去除机制将被确定。该项目将产生大量关于bioPM附着力和再悬浮分数的经验数据。该研究的新颖性进一步体现在将从6周至3岁的婴儿/幼儿的托儿中心收集的加速度测量数据整合到机器人的设计中，用于气溶胶物理和微生物学界面的研究。最后，该研究将创新地使用基于树莓派的低成本颗粒传感器阵列来探索重悬浮生物膜浓度的时空变化，这将为多区域物质平衡模型的发展提供信息。本科生将参与bioPM实验，作为跨学科社区服务工程项目（EPICS）团队的一部分，参与K-12学校室内空气质量问题的服务学习项目，以及基于树莓派的传感器和机器人的开发。新的研究生课程内容bioPM材料平衡建模将被创建。该项目将积极涉及普渡大学MCDLS的教师、家长、看护人员和建筑设施管理人员，让那些直接与婴儿及其室内环境互动的人参与进来。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。

Infants and toddlers spend over 90% of their time indoors and are thus exposed to numerous agents in the indoor environment. House dust is heavily enriched with an incredible diversity of microbes and allergens. Early-life inhalation exposures to the microbial and allergenic content of indoor dust can play a significant role in both the development of, and protection against, asthma and allergic diseases. As infants crawl, play, and learn to walk, they stir-up (resuspend) concentrated clouds of biological particulate matter (bioPM: bacteria, fungi, pollen) from settled dust. The resuspension and adhesion of indoor bioPM remains poorly characterized. New research is needed to uncover the underlying transport mechanisms that govern bioPM exposures during this critical period in human immunological development. The goal of this project is to explicitly elucidate the fundamental mechanisms governing the adhesion, resuspension, and airborne transport of bioPM in early-childhood microenvironments. Exposure will be determined using a novel robot designed to simulate the movement of infants in the indoor environment and exposure to bioPM. This research has the potential to transform our understanding of infant exposure to bioPM at a critical stage in their development. Through a mechanistic framework, this project will make substantial contributions towards a fundamental understanding of the complex adhesion and human-driven resuspension processes that control the emissions, airborne transport, and fate of bioPM from settled dust in indoor environments. The specific objectives are: 1) investigate the adhesive interactions between bioPM and indoor surfaces through atomic force microscopy and explore the impact of bioPM morphology, hydrophobicity, charge, and humidity on adhesion forces; 2) develop a novel robotic platform to simulate infant/toddler movements informed by biometric data collected at the Purdue Miller Child Development Laboratory School (MCDLS) and to investigate aerodynamic, vibrational, and electrostatic bioPM removal forces; and 3) discover how infant/toddler movements resuspend bioPM through chamber experiments with the robot and develop a material balance model to predict bioPM fate and transport. This research will create new knowledge on how bioPM physiochemical properties affect adhesion forces to indoor surfaces. For the first time, bioPM removal mechanisms induced by forms of locomotion unique to infants will be determined. This project will generate extensive empirical data on bioPM adhesion forces and resuspension fractions. The novelty of the research is further exemplified by the integration of accelerometry data collected in a childcare center with infants/toddlers from 6 weeks to 3 years of age into the design of a robot for use in research at the interface of aerosol physics and microbiology. Lastly, the study will make innovative use of a Raspberry Pi-based low-cost particle sensor array to explore spatiotemporal variations in concentrations of resuspended bioPM which will infom the development of a multi-zone material balance model. Undergraduate students will participate in the bioPM experiments, in service learning projects on indoor air quality issues in K-12 schools as part of an interdisciplinary Engineering Projects in Community Service (EPICS) team, and in the development of the Raspberry Pi-based sensors and robot. New graduate course content on bioPM material balance modelling will be created. The project will actively involve Purdue MCDLS teachers, parents, custodial staff, and building facility managers to engage those who interact directly with infants and their indoor environments.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.