NER: Chemical Probing of Biosensor Nano-environments using Dynamic AFM

生物传感器在基因组分析、战剂检测和医学诊断中变得越来越重要。为了优化这些设备的性能，必须开发新的工具来表征其功能背后的分子水平现象。这项探索性的纳米技术提案旨在开发一种新的方法来测量生物传感器表面的纳米级特性，利用原子力显微镜（AFM）的动态模式下的超细分辨率。它们必须促进特定分析物的结合，同时阻止外来物质的结合。通常，这些目标是通过构建异质表面与聚合物与受体特异性所需的分析物。为了在不牺牲选择性的情况下最大化产量，必须将最佳密度和厚度的聚合物施加到表面。在这项工作中，PI希望测量生物分子在传感器表面附近穿过的纳米级能量景观，以指导生物传感器的合理设计。动态AFM方法包括振动AFM悬臂梁并测量样品接近AFM针尖时的振幅衰减。振幅衰减对聚合物立体力比偏转更敏感，因此可以使用特定配体-受体测量所需的尖端。在这里，PI将在模型生物传感器系统中测量动态和常规AFM力曲线。通过对悬臂梁振动的理论描述，我们希望证明动态方法的灵敏度和准确性。如果成功，该项目将在许多方面产生影响。首先，该技术将提供一个独特的纳米探针的异质表面相关的生物传感器。它也将能够测量聚合物的空间力与纳米横向分辨率，与润滑和胶体加工的影响。最后，由于上皮细胞和细菌细胞表面也包含特定的粘附受体在一起的聚合物环境中，动态AFM力的方法可能会出现作为一个强大的工具，在细胞-细胞和细胞表面粘附的研究。

Biosensors are becoming increasingly important for genomic analysis, detection of warfare agents, and medical diagnostics. To optimize the performance of these devices, new tools must be developed to characterize the molecular-level phenomena that underlie their function. This exploratory nanotechnology proposal aims to develop a new method to measure nanoscopic properties of biosensor surfaces, utilizing the ultrafine resolution of atomic force microscopy (AFM) in dynamic mode.Biosensors must perform two functions at once. They must encourage the binding of specific analytes while discouraging the binding of adventitious material. Typically, these goals are achieved by building heterogeneous surfaces with antifouling polymers together with receptors specific for desired analytes. To maximize yield without sacrificing selectivity, an optimal density and thickness of polymer must be applied to the surface. In this work, the PI hopes to measure the nanoscopic energy landscape that a biomolecule traverses near the sensor surface in an attempt to guide the rational design of biosensors. For a realistic measurement, both polymer steric interactions and specific ligand-receptor interactions must be measured simultaneously.The dynamic AFM method involves oscillating the AFM cantilever and measuring the amplitude attenuation as the sample approaches the AFM tip. Amplitude attenuation is more sensitive to polymer steric forces than deflection, so the sharp tips required for specific ligand-receptor measurements can be used. Here, the PI will measure dynamic and conventional AFM force curves in a model biosensor system. Using a theoretical description of cantilever oscillation, we hope to demonstrate the sensitivity and accuracy of the dynamic method.If successful, the project will have an impact on many fronts. First, the technique will provide a unique nanoscopic probe of heterogeneous surfaces pertinent to biosensors. It will also be able to measure polymer steric forces with nanometer lateral resolution, with implications for lubrication and colloidal processing. Finally, since epithelial and bacterial cell surfaces also contain specific adhesion receptors together in a polymeric environment, the dynamic AFM force method may emerge as a powerful tool in the study of cell-cell and cell-surface adhesion.