Ion Selective Quantum Dots for Intracellular Mapping of Sodium Sparks in Cardiac

用于心脏钠火花细胞内图谱的离子选择性量子点

• 批准号: 8074080
• 负责人: Heather A Clark
• 金额: $ 25.75万
• 依托单位: NORTHEASTERN UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-05-01 至 2013-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8074080
• 关键词: Action Potentials; Affect; Arrhythmia; Attenuated; Biocompatible; Biological; Calcium; Cardiac; Cardiac Myocytes; Categories; Cell physiology; Cells; Cytosol; Disease; Dose; Dyes; Environment; Fluorescence; Goals; Image; Imaging Device; Ion Channel; Ionophores; Ions; Knowledge; Lead; Literature; Long QT Syndrome; Maps; Measurement; Measures; Membrane; Molecular Probes; Monitor; Nature; Optics; Oral cavity; Pharmaceutical Preparations; Physiological; Plasticizers; Polymers; Potassium; Potassium Channel Blockers; Prevention; Process; Property; Quantum Dots; Resolution; Signal Transduction; Sodium; Sodium Channel; Sodium Channel Blockers; Solutions; Spatial Distribution; System; Time; Validation; base; channel blockers; nanosensors; patch clamp; public health relevance; response; sensor; tool

DESCRIPTION (provided by applicant): Ion-selective quantum dots (ISQDs) are ion-selective polymer-based optical nanosensors that incorporate quantum dots (QDs) into the core of the sensor. A sodium-selective ISQD measures sodium over the range of 1mM to 1 M with 100 fold selectivity over potassium and a resolution of 80 5M. Ion-selective quantum dots consist of a quantum dot, a pH sensitive dye, and an ion-selective polymer. Selective ion extraction into the polymer matrix causes a pH change inside the matrix therefore changing the absorbance properties of the pH sensitive dye. The change of absorbance attenuates the intensity of the quantum dot by directly absorbing its fluorescence emission. Our hypothesis is that using ISQDs to map the spatial distribution of intracellular sodium will reveal a heterogeneous distribution of ion activity during the action potential of a cardiac cell. We base our hypothesis on the following: First, ISQDs are the only sodium probes available that are selective over physiological levels of potassium, photostable, and biocompatible. Second, it has been shown that fluxes of ions at the opening of an ion channel create localized regions of high ion concentrations, or calcium sparks . Because of the nature of the channel sodium sparks should be present at the opening of sodium channels, however there are very few documented cases in the literature. We believe that using better tools for sodium imaging, such as ISQDs, will provide a wealth of information on this little known process. The specific aims of this application period are: 1. To tailor ISQDs to be compatible with the analytical requirements of measuring sodium in an intracellular environment. A robust sensor must demonstrate optimal results in the following categories: physiologically relevant dynamic range, leaching/lifetime of sensors, and size. 2. To validate the response of ISQDs to sodium in the intracellular environment. ISQDs must show a response to changes in sodium in the intracellular environment that are comparable to those achieved in solution studies in Specific Aim 1. Validation will be performed using simultaneous patch clamp and optical recording in a well-defined cell system. Additionally, a comparison to patch-clamp alone (no ISQDs) and CoroNa dyes will be performed. A dose response to the effects of known channel blockers will also be carried out. 3. To map the spatial distribution of sodium in cardiac myocytes. Sodium fluxes through ion channels in the outer membrane lead to inhomogeneous distributions of sodium concentration in the cell, at least during the duration of the open channel. Sodium sparks will be identified in cardiac myocytes, and will be evaluated for effects to sodium channel blockers. PUBLIC HEALTH RELEVANCE: The ultimate goal of this application is to develop and use a new intracellular imaging tool, Ion- Selective Quantum Dots to map sodium microdomains in cardiac cells. These probes will provide crucial information on ion channel distribution that is not available with current tools. Ultimately, this tool will provide new knowledge of cardiac action potentials and possibly lead to the prevention of fatal arrhythmias in diseases such as Long QT syndrome.

描述（由申请人提供）：离子选择性量子点（ISQD）是基于离子选择性聚合物的光学纳米传感器，将量子点（QD）纳入传感器的核心。钠选择性ISQD可在1 mM至1 M范围内测量钠，选择性是钾的100倍，分辨率为80 5 M。离子选择性量子点由量子点、pH敏感染料和离子选择性聚合物组成。选择性离子萃取到聚合物基质中导致基质内的pH变化，从而改变pH敏感染料的吸光度特性。吸光度的变化通过直接吸收其荧光发射来衰减量子点的强度。我们的假设是，使用ISQD映射细胞内钠的空间分布将揭示在心肌细胞的动作电位的离子活性的不均匀分布。我们的假设基于以下几点：首先，ISQD是唯一可用的钠探针，其对钾的生理水平具有选择性、光稳定性和生物相容性。第二，已经表明，离子通道开口处的离子通量产生高离子浓度的局部区域或钙火花。由于通道的性质，钠火花应该存在于钠通道的开口处，然而文献中记录的病例很少。我们相信，使用更好的钠成像工具，如ISQD，将为这个鲜为人知的过程提供丰富的信息。本申请期的具体目标是：1。定制ISQD，使其符合测量细胞内环境中钠的分析要求。一个强大的传感器必须证明在以下类别的最佳结果：生理相关的动态范围，浸提/传感器的寿命，和大小。2.验证ISQD对细胞内环境中钠的响应。ISQD必须显示出对细胞内环境中钠变化的反应，与特定目标1中溶液研究中达到的反应相当。将在明确定义的细胞系统中使用同时膜片钳和光学记录进行验证。此外，还将与单独的膜片钳（无ISQD）和CoroNa染料进行比较。还将对已知通道阻滞剂的作用进行剂量反应。3.绘制心肌细胞钠离子空间分布图。通过外膜中的离子通道的钠通量导致细胞中钠浓度的不均匀分布，至少在开放通道的持续时间期间。将在心肌细胞中识别钠火花，并评价对钠通道阻滞剂的影响。 公共卫生关系：该应用的最终目标是开发和使用一种新的细胞内成像工具，离子选择性量子点，以绘制心脏细胞中的钠微区。这些探针将提供离子通道分布的重要信息，这是目前的工具无法提供的。最终，该工具将提供心脏动作电位的新知识，并可能导致预防长QT综合征等疾病中的致命性心律失常。