Polymer-Free Nanosensors To Visualize Biochemical Dynamics in Dendritic Spines

描述（由申请人提供）：树突棘是中枢神经系统中整合兴奋性和抑制性输入所必需的。棘的精细结构，颈小至100纳米，头小至400纳米，使它们能够形成超结构室，局部控制信号和生化微环境。脊柱的超结构不容易允许标准的表征方法，如共聚焦成像和电生理学。双光子和STED成像技术的最新进展对于解析结构和位置至关重要，但对生化环境的深入了解仍然难以捉摸。我们的目标是使用一种新型的无聚合物纳米传感器（PFN）结合双光子激光扫描显微镜来表征树突棘的生化环境。具体来说，我们建议评估脊柱中的离子动力学，从钠离子开始，然后很容易地将平台扩展到其他离子，如氯离子、钙离子和钾离子。由于通过树突棘的颈部装载纳米传感器，即使是20纳米的纳米传感器也可能是困难的，因此我们建议开发并表征一种新型纳米传感器：一种不含聚合物的配方，具有油而不是珠的机械特性。这将使我们能够将pfn加载到甚至很小的结构中，然后监测荧光强度，作为分析物的实时可逆指标

DESCRIPTION (provided by applicant): Dendritic spines are essential for integrating excitatory and inhibitory inputs in the central nervous system. The fine structure of the spines, with necks as small as 100 nm and heads as small as 400 nm, allow them to form ultra-structural compartments with localized control of signaling and biochemical microenvironment. The ultra-structure of spines does not readily allow for standard methods of characterization, such as confocal imaging and electrophysiology. Recent progress in two-photon and STED imaging has been essential to resolving structure and location, but obtaining insight to the biochemical environment remains elusive. Our goal is to use a novel Polymer-Free Nanosensors (PFN) combined with 2-photon laser scanning microscopy to characterize the biochemical environment of dendritic spines. Specifically, we propose assessing ion dynamics in the spines, starting with sodium and then easily extending the platform to other ions such as chloride, calcium, and potassium. Since loading nanosensors, even ones as small as 20 nm, through the necks of dendritic spines might prove difficult, we propose developing and characterizing a novel type of nanosensor: a polymer-less formulation that has the mechanical properties of an oil rather than a bead. This would allow us to load PFNs into even small structures, and then monitor fluorescence intensity as a real-time, reversible indicator of analyte concentration. Since the spine neck forms the barrier that diffusionally isolates the synapse, one predicts that these altered morphologies perturb the biochemical and electrical compartmentalization of the synapse and spine. Our proposal will determine the role of the spine neck in shaping synaptically-evoked signals and will set the foundation necessary for revealing the functional consequences of the morphological changes seen in disease states.