Mapping Elastic Properties of Complex Biological Tissue

大多数生物组织是相当复杂的结构，在微观和纳米尺度上具有材料性质和结构的不均匀性。 组织的结构和功能的详细表征将通过以显微分辨率映射组织的弹性特性来服务。 原子力显微镜（AFM）是一种理想的工具，用于通过在组织上感兴趣的整个域中的大量点处进行纳米压痕测试并使用适当的数学模型来提取每个点处的所需弹性参数来构建此类地图。 这种程序通常需要分析数百或数千个数据集。 在没有自动化的情况下，这是一个非常繁琐的过程，这阻碍了其用于生物组织（例如软骨）的弹性特性的详细映射。 我们正在建立一个强大的自动化工具，将允许在任何分辨率的常规弹性映射。 目标是双重的：首先，我们想在微观结构水平上研究和比较天然和组织工程软骨以及其他聚合物凝胶样组织的弹性特性。 与此同时，我们研究更简单的人工凝胶，我们增加了更多的复杂性（添加各种分子成分和各种不均匀性），并使用AFM结合宏观和渗透测量，努力阐明决定这种组织的弹性行为的因素。 第二，弹性地图建设的自动化软件的开发将创建一个工具，可以并将被广泛用于各种项目的内部合作者，如一个与NIDCD合作者调查的弹性特性的覆膜在内耳，和支持的脂质双层的材料特性的测量。

Most biological tissues are rather complex structures with inhomogeneities in material properties and structure at micro- and nanoscopic scales. Detailed characterization of the structure and function of tissues would be served by mapping elastic properties of the tissue with microscopic resolution. The atomic force microscope (AFM) is an ideally suited tool for constructing such maps by doing nano-indentation tests at a large set of points throughout a domain of interest on the tissue and using appropriate mathematical models to extract the desired elastic parameters at each point. Such procedure typically requires analysis of hundreds or thousands of data sets. Without automation, this is a very tedious process which is hindering its use for detailed mapping of elastic properties of biological tissue such as cartilage. We are building a powerful automation tool that will allow routine elasticity mapping at any resolution. The goal is twofold: First we want to investigate and compare the elastic properties of natural and tissue-engineered cartilage and other polymer gel-like tissues at the microstructure level. At the same time we investigate simpler artificial gels to which we add ever more complexity (adding various molecular components and various inhomogeneities) and use the AFM in conjunction with macroscopic and osmotic measurements in an effort to elucidate the factors determining the elastic behavior of such tissues. Second, development of the automation software for elastic map construction will create a tool that can and will be used widely by intramural collaborators in a variety of projects, such as the one with NIDCD collaborators on investigating the elastic properties of the tectorial membrane in the inner ear, and the measurement of material properties of supported lipid bilayers.