EAGER: Optical Coherence Elastography (OCE): A novel tool for rapid, nondestructive, spatially resolved quantification of mesoscale biofilm mechanical properties

1701105 Wells，乔治F.附着于表面的细菌群落形成生物膜，这在工程生物反应器和自然环境中都很重要。尽管生物膜结构作为生物膜生长和活性的基本介质的重要性，但关于生物膜结构和控制生物质在生物膜中保留的机械性质之间的关系知之甚少。为了解决这一知识缺口，PI建议开发一种新的方法，称为光学相干弹性成像，用于快速定量3D映射生物膜中的机械特性。项目团队将开发光学相干弹性成像方法，并使用它来分析混合培养生物膜的特性和动力学，这些生物膜代表生物脱氮（N）。将围绕两个具体目标组织工作：1）开发动态光学相干弹性成像方法，用于环境生物膜中弹性模量的中尺度无损映射;以及2）采用光学相干弹性成像来量化混合培养N-循环生物膜中中的中尺度生物膜机械特性、形态和性能之间的关系。光学相干弹性成像的初始应用将涉及杨氏模量和剪切模量中的中尺度梯度与生物膜粗糙度、内部孔隙率和厚度的变化。非破坏性弹性成像将使时间序列测量的中尺度结构和力学特性，在这些重要的环境生物膜的发展。因此，该项目促进了对环境生物膜中物理结构和机械性能之间关键但知之甚少的相互关系的理解。宏观生物膜的特征，如生物量积累和化学转化率被认为是与中尺度生物膜的结构和机械性能，但绝大多数的工作生物膜结构集中在微观尺度。光学相干弹性成像将首次实现在中尺度上对生物膜形态和机械特性进行共定位、实时、非侵入性的原位映射。所提出的光学相干弹性成像方法采用剪切波换能器传播生物膜中的局部变形。然后通过相敏光学相干断层扫描连续成像变形。通过将变形的传播速度与局部密度和弹性或粘弹性性质相关联来获得空间分辨的中尺度生物膜机械性质分布。光学相干弹性成像最近已被应用于生物医学研究，但它是一种全新的生物膜表征方法。所提出的工作的结果将打开新的可能性，以阐明中尺度生物膜特性，微尺度生物膜组成，和环境生物膜中的紧急系统功能之间的相互作用。 该项目将资助一名博士。学生和本科生。项目实验系统将用于设计实验的核心实验室课程在西北和示范推广到K-12学生和社区团体。

1701105Wells, George F.Bacterial communities attached to surfaces form biofilms which are important in both engineered bioreactors and natural environments. Despite the importance of biofilm structure as an essential mediator of biofilm growth and activity, little is known about the relationship between biofilm structure and mechanical properties that control retention of biomass in biofilms. To address this knowledge gap, the PIs propose to develop a novel methodology, termed Optical Coherence Elastography, for rapid quantitative 3D mapping of mechanical properties in biofilms.The project team will develop the Optical Coherence Elastography method and use it to assay properties and dynamics of mixed-culture biofilms representative of those employed for biological nitrogen (N) removal. Efforts will be organized around two specific objectives: 1) Develop a dynamic Optical Coherence Elastography method for mesoscale nondestructive mapping of elastic moduli in environmental biofilms; and, 2) Employ Optical Coherence Elastography to quantify the relationship between mesoscale biofilm mechanical properties, morphology, and performance in mixed culture N-cycling biofilms. Initial applications of Optical Coherence Elastography will relate mesoscale gradients in Young's and Shear moduli to variation in biofilm roughness, internal porosity and thickness. Nondestructive elastography will enable time-series measurement of mesoscale structural and mechanical features during development of these essential environmental biofilms. Thus, this project advances understanding of critical yet poorly understood interrelationships between physical structure and mechanical properties in environmental biofilms. Macroscale biofilm characteristics such as biomass accumulation and chemical transformation rates are known to be linked to mesoscale biofilm structure and mechanical properties, yet the vast majority of work on biofilm structure has focused on the microscale. Optical Coherence Elastography will enable, for the first time, co-located, real-time, non-invasive, in situ mapping of biofilm morphology and mechanical properties at the mesoscale. The proposed Optical Coherence Elastography methodology employs a shear wave transducer to propagate localized deformations in biofilms. Deformations are then continuously imaged via phase sensitive optical coherence tomography. The spatially resolved mesoscale biofilm mechanical property distribution is obtained by relating the speed of propagation of deformations to local density and elastic or viscoelastic properties. Optical Coherence Elastography has recently been applied for biomedical research, but is an entirely new approach to biofilm characterization. Results of the proposed work will open new possibilities to elucidate the interplay between mesoscale biofilm properties, microscale biofilm composition, and emergent system function in environmental biofilms. This project will support one Ph.D. student and as undergraduate student. Project experimental systems will be used to design experiments for a core laboratory course at Northwestern and demonstrations for outreach to K-12 students and community groups.