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，许多过程都会产生或消耗热能，因此可以通过测量温度来监控。现代科学对此作出了回应，开发了广泛的加热器和温度计，这些加热器和温度计采用了各种潜在的机制，包括光学、电气和化学。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，科学家们不断推动能够在更小尺度上工作的工具。具体地说，微纳尺度温度的精确控制和测量是非常困难的，没有单一的方法可以提供完美的解决方案。本项目旨在建立一种能够在细胞友好型水基环境中工作的精确纳米级加热器/温度计显微镜。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(或热)。除此之外，它还可以放置在样本上的任何位置，并在移动到另一个位置之前进行测量，以无限期重复这一过程。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，但在这个项目期间将探索的两个例子如下：在细胞生物学中，温度的控制为科学家提供了一种迷人而灵活的方式来监控或改变细胞行为，甚至诱导细胞死亡的能力。最后这一点已经被一种非常有希望的癌症治疗新方法所利用，该方法被称为“纳米颗粒介导的光热疗法”。在这项技术中，专门针对癌细胞设计的金纳米颗粒吸收特定波长的光并加热。这种热能直接导致癌细胞死亡或释放预先加载的治疗药物。然而，热诱导死亡的机制还不是很清楚，主要是因为未知的纳米粒子温度和它们在细胞中的不受控制的分布。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。我们将要开发的工具可以在一个简单的实验中提供答案，它将加热器/温度计精确地放置在不同细胞上精心选择的位置，一次一个，并向每个细胞提供准确的热量。另一个例子是测量不同活细胞的温度。细胞的温度取决于它的新陈代谢和对周围环境的反应，这并不令人惊讶。传统上，生物学家使用一系列光学工具来测量细胞内和周围的温度。然而，解释这些测量充满了困难，导致了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种非常容易理解的、明确的温度测量方法。这一点再加上精确定位单个细胞不同区域的测量结果的能力，将为这场激烈的科学辩论提供宝贵的数据。最终，我们的仪器将提供一种简单易用和灵活的工具来测量和改变与细胞和亚细胞水平的尖端研究相关的长度尺度的温度。

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.