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: 8111406
• 负责人: Heather A Clark
• 金额: $ 25.29万
• 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/8111406
• 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）（QD）纳入传感器的核心。钠选择性ISQD在1mm至1 m的范围内测量钠，而100倍的选择性比钾进行了100倍的选择性，分辨率为80 5m。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。选择性离子提取到聚合物基质中会导致矩阵内部的pH变化，因此改变了pH敏感染料的吸光度。吸光度的变化通过直接吸收其荧光发射来减轻量子点的强度。我们的假设是，使用ISQD绘制细胞内钠的空间分布将揭示心脏细胞作用电位期间离子活性的异质分布。我们以下假设为基础：首先，ISQD是唯一可在生理水平的钾，光stostable和生物相容性的钠探针中选择性的。其次，已经表明，离子通道开口处的离子通量会产生高离子浓度或钙火花的局部区域。由于钠频道的开口应存在通道钠火花的性质，但是文献中很少有记录的病例。我们认为，使用更好的工具进行钠成像，例如ISQD，将为这个鲜为人知的过程提供大量信息。此应用期间的具体目的是：1。量身定制ISQD与在细胞内环境中测量钠的分析要求兼容。强大的传感器必须在以下类别中展示最佳结果：生理相关的动态范围，传感器的浸出/寿命以及大小。 2。在细胞内环境中验证ISQD对钠的反应。 ISQD必须在细胞内环境中表现出对钠的变化的反应，这些反应与特定目标1中的解决方案研究相当。将使用同时定义的细胞系统中的同时贴片夹和光学记录进行验证。此外，将进行与贴片钳（无ISQD）和电晕染料进行比较。还将对已知通道阻滞剂的影响产生剂量反应。 3。绘制心肌细胞中钠的空间分布。通过外膜的离子通道钠通量至少在开放通道的持续时间内导致细胞中钠浓度的不均匀分布。钠火花将在心肌细胞中鉴定出来，并将评估对钠通道阻滞剂的效果。 公共卫生相关性：此应用程序的最终目标是开发和使用新的细胞内成像工具，离子选择性量子点来绘制心脏细胞中的钠微区域。这些探针将提供有关当前工具无法使用的离子通道分布的重要信息。最终，该工具将提供有关心脏作用电位的新知识，并可能导致预防长期QT综合征等疾病中致命的心律不齐。