An Aqueous Scanning Thermal Microscope for nanoscale thermal biology

测量和操纵热量的能力是任何科学家工具箱中的基本工具。生物过程、化学反应甚至基础物理学都与温度有着内在的联系。通过改变温度，生物、化学和物理过程可以加速、减慢甚至停止。同样，许多过程导致热能的产生或消耗，因此可以通过测量温度来监测。现代科学对此做出了回应，开发了各种各样的加热器和温度计，这些加热器和温度计采用各种基本机制，包括光学，电学和化学。然而，这不应该让我们相信温度是一个“解决”的问题，不再需要创新。一个非常明显的例子是，科学家们不断推动在更小的长度尺度上工作的工具。具体来说，在微米和纳米尺度上精确控制和测量温度是非常困难的，没有一种方法可以提供完美的解决方案。本项目是建立一个精确的纳米尺度加热器/温度计显微镜，可以在细胞友好的水基环境中工作。该工具背后的技术意味着它可以测量样品纳米尺寸区域的温度（或加热）。除此之外，它还可以定位在样品上的任何位置，并在移动到另一个位置之前进行测量，以无限期地重复该过程。该工具与其他形式的显微镜完全兼容，允许同时进行光学，地形和热测量。这种灵活性在生物学中有广泛的应用，但在本项目中将探索的两个例子如下：在细胞生物学中，温度控制为科学家提供了一种迷人而灵活的方法来监测或改变细胞行为，甚至诱导细胞死亡的能力。这最后一点已被用于一种非常有前途的癌症治疗新方法，称为“纳米粒子介导的光热疗法”。在这项技术中，专门设计用于靶向癌细胞的金纳米颗粒吸收特定波长的光并加热。这种热量可以直接诱导癌细胞死亡或释放预先装载的治疗药物。然而，热诱导死亡的机制知之甚少，主要是因为未知的纳米颗粒温度和它们在细胞中不受控制的分布。传统的方法需要大量的重复实验，以及间接计算粒子温度来回答这些问题。我们将开发的工具可以在一个简单的实验中提供答案，通过精确地将其加热器/温度计定位在不同细胞上精心选择的位置，一次一个，并向每个细胞提供精确的热量。另一个例子是测量不同活细胞的温度。毫不奇怪，细胞的温度取决于其新陈代谢及其对周围环境的反应。传统上，生物学家使用一系列光学工具来测量细胞内部和周围的温度。然而，解释这些测量结果充满了困难，导致科学上的分歧和没有共识。我们将在这个项目中使用的温度计是基于一个非常好理解的，明确的测量温度的方式。再加上能够精确定位单个细胞不同区域的测量，将为这场活跃的科学辩论提供有价值的数据。最终，我们的仪器将提供一个简单易用和灵活的工具来测量和改变温度的长度尺度相关的前沿研究在细胞和亚细胞水平。

The ability to measure and manipulate heat is a fundamental tool in any scientist's toolkit. Biological processes, chemical reactions and even fundamental physics are all intrinsically linked to temperature. By changing temperature, biological, chemical and physical processes can be sped-up, slowed-down or even stopped. Likewise, many processes result in the generation or consumption of thermal energy so can be monitored by measuring temperature. Modern science has responded to this by developing a wide range of heaters and thermometers that employ various underlying mechanisms, including optical, electrical and chemical. However, this shouldn't lead us to believe that temperature is a 'solved' problem that no longer requires innovation. A very clear example of this is the continuing push of scientists for tools that work at ever smaller length scales. Specifically, the accurate control and measurement of temperature at the micro- and nano-scale is very difficult, with no single approach offering a perfect solution.This project is to build an accurate nano-scale heater/thermometer microscope that can operate in cell-friendly, water based environments. The technology behind this tool means that it can measure the temperature of (or heat) a nano-sized region of a sample. In addition to this, it can be positioned at any site on a sample and make a measurement before being moved to another site to repeat the process indefinitely. The tool is completely compatible with other forms of microscopy, allowing optical, topographic and thermal measurements to be made simultaneously. This flexibility has a wide range of applications in biology but two examples that will be explored during this project are given below:In cell biology, control of temperature gives scientists a fascinating and flexible way to monitor or change cell behavior, even the ability to induce cell death. This last point has been exploited in a highly promising new approach to cancer treatment called 'nanoparticle-mediated photothermal therapy'. In this technique, gold nanoparticles specifically designed to target cancer cells absorb a light of specific wavelength and heat up. This heat can induce the death of the cancer cells directly or release pre-loaded therapeutic drugs. However, the mechanism of heat-induced death is poorly understood, mainly because of unknown nanoparticle temperature and their uncontrolled distribution in cells. Traditional methods would require a huge number of repeat experiments, together with indirect calculations of particle temperature to answer these questions. The tool we will develop can provide answers within one simple experiment by precisely locating its heater/thermometer at carefully chosen sites on different cells one at a time and delivering an exact quantity of heat to each.Another example is measuring the temperature of different living cells. It should be no surprise that a cell's temperature is dependent upon its metabolism and its activity in response to the surrounding environment. Traditionally, biologists have used a range of optical tools to measure the temperature in and around cells. However, interpreting these measurements is fraught with difficulty, resulting in scientific disagreement and no consensus. The thermometer we will use in this project is based on a very well understood, unambiguous way of measuring temperature. This coupled with the ability to precisely locate the measurement on different regions of a single cell will offer valuable data to this lively scientific debate. Ultimately, our instrument will provide a simple to use and flexible tool to measure and change temperature at length scales relevant to cutting edge research at the cellular and subcellular level.