Energy and electron transfer between quantum dots and biomolecules

量子点因其稳定性、亮度和颜色范围广而被用作荧光染料的替代品。然而，这些半导体纳米晶体还具有其他特性，使它们有可能成为一种全新的纳米级生物传感器：它们可以根据细胞内的特定过程关闭或打开（或改变颜色）。在我们之前的工作中，我们定义了可能导致量子点荧光改变的生物相关过程的类型，并说明了量子点作为活细胞内氧化还原电位传感器的使用。在这项工作中，我们有两个具体的目标：(1)利用这些一般原理来创建细胞膜电位和离子通量的传感器。我们将把它应用于细菌钠通道的具体情况，最终目标是使用传感器探测动作电位。我们将确定所见荧光变化背后的确切光物理机制，从而使新型纳米粒子传感器的创建变得更加容易。(2)测量量子点荧光间歇性（“闪烁”），因为粒子遇到活细胞，被吸收，旅行到不同的细胞内位置，并被处理。这可能使眨眼现象被用作细胞内状况的真正纳米级探针。

Quantum dots have been used in biological applications as an alternative to fluorescent dyes because of their stability, brightness, and wide range of colours. However, these semiconductor nanocrystals also possess other properties that make them potentially useful as a whole new class of nanoscale biosensors: those that turn off and on (or change colour) in response to a specific process within a cell. In our previous work, we defined the types of biologically-relevant processes that might result in alterations of quantum dot fluorescence, and illustrated the use of quantum dots as sensors for redox potential within living cells. In this work, we have two specific aims: (1) to use these general principles to create a sensor for cellular membrane potential and ion flux. We will apply this to the specific case of a bacterial sodium channel, with the eventual goal of using the sensor to probe action potentials. We will determine the exact photophysical mechanisms behind the fluorescence changes seen, and thus to enable the easier creation of new classes of nanoparticle-based sensors. (2) To measure quantum dot fluorescence intermittency ("blinking") as the particles encounter living cells, are taken up, travel to different intracellular locations, and are processed. This may allow the phenomenon of blinking to be used as a truly nanoscale probe of intracellular conditions.