BIOMOLECULE-DIRECTED EVOLUTION OF INORGANIC NANOMATERIALS

从数十亿年前出现的极其简单的微生物开始，我们周围的植物和动物的多样性和复杂性是进化的结果。反过来，生物体的进化能力本身归因于DNA，DNA构成了地球上生命的蓝图。DNA可以发生突变，其中一些可能会产生“更强大”的生物体。在这个跨学科的研究项目中，我们从自然界中获得灵感，利用DNA技术进化出具有目标特性的无机纳米材料。随着骨骼、牙齿和贝壳等结构的产生，大自然表明，可以在非常温和的条件下生产出性能完美优化的无机材料。虽然生物体显然使用许多策略来实现这一目标，但所有这些策略都有一个共同的特征：自然界使用有机分子控制无机固体的形成。这些生物分子本身就是进化选择的结果，适者生存，以产生具有目标尺寸，形状，方向和多晶型的材料。分子生物学的专业知识现在已经达到可以使用DNA技术来进化巨大的生物分子库的水平。与高通量筛选方法相结合，因此可以产生用于日益多样化的靶应用的生物分子。虽然这种令人兴奋的生物进化到实验室时间尺度的减少已被用于改善有机催化等应用，但其在材料合成方面的巨大潜力几乎完全未被开发。这项研究提案将解决这一挑战，并采用一种新的方法来进化DNA编码的纳米材料。我们的战略基于三个关键因素。(1)我们将利用两个不同的DNA库-编码生物分子库-以前从未筛选过材料合成，但非常适合此目的。(2)我们将利用一个全新的基于微滴的平台（使用微流体设备）。封装在单个微滴内的单个DNA分子将用于表达独特的生物分子。硫化镉，硫化铜和磁铁矿（磁性氧化铁）的纳米颗粒将在这些独特的微环境中合成。(3)我们将直接筛选合成纳米材料的特性。将使用荧光激活细胞分选（FACS）或磁性分离来分离含有具有目标光致发光或磁性特性的"获胜"纳米颗粒的液滴。从"获胜"的液滴中回收DNA，然后能够表达"获胜"的蛋白质，这可以用于大规模合成获胜的纳米颗粒。最后，我们的实验方法将使我们能够将生物分子的结构和功能联系起来。虽然研究人员在过去的50年里研究了从生物矿物中提取的生物分子，但我们仍然对这些控制因素（如多态性）的理解非常有限。在这里，我们的多样化文库源自独特的蛋白质支架（"adhiron"），其表现出易于结晶的理想特性。从这种能力中获益，我们将确定“获胜”蛋白质的3D结构，并与选定的“失败者”进行比较，将能够获得对其活性起源的独特见解。

From the extremely simple micro-organisms which appeared billions of years ago, the diversity and complexity of the plants and animals currently surrounding us results from evolution. In turn, the ability of organisms to evolve is itself attributed to the DNA which forms the blueprint of life on earth. DNA can undergo mutations, some of which may generate a "stronger" organism. As organisms exist in a competitive environment, the stronger species survive to transmit their "winning" DNA to new progeny and future generations.In this interdisciplinary research project, we gain inspiration from nature to use DNA-based technologies to evolve inorganic nanomaterials with targeted properties. With the production of structures such as bones, teeth and seashells, nature shows that it is possible to produce inorganic materials whose properties are perfectly optimised for their function under very mild conditions. While organisms clearly achieve this using many strategies, all are united by one common feature; nature controls the formation of inorganic solids using organic molecules. These biomolecules are themselves the result of evolutionary selection such that the fittest survive to produce materials with target size, shape, orientation and polymorph.Expertise in molecular biology has now reached levels where DNA technologies can be used to evolve huge libraries of biomolecules. In combination with high throughput screening methods, it has therefore become possible to generate biomolecules for increasingly diverse target applications. While this exciting reduction of biological evolution to the laboratory timescale has been used to improve applications such as organic catalysis, its huge potential in materials synthesis remains almost entirely untapped. This research proposal will address this challenge, and employ a novel approach to evolve DNA-encoded nanomaterials. Our strategy is based on three key factors.(1) We will utilize two diverse DNA libraries - which encode for libraries of biomolecules - that have never before been screened for material synthesis, but that are very well suited for this purpose.(2) We will utilize a completely new micro-droplet-based platform (using microfluidic devices). Single DNA molecules encapsulated within single micro-droplets will be used to express unique biomolecules. Nanoparticles of cadmium sulfide, copper sulfide and magnetite (magnetic iron oxide) will then be synthesised within these unique micro-environments.(3) We will screen directly for the PROPERTIES of the synthesized nanomaterials. Droplets containing "winning" nanoparticles with target photoluminescent or magnetic properties will be isolated using fluorescence activated cell sorting (FACS) or magnetic separation. Recovery of the DNA from the "winning" droplets then enables expression of the "winning" protein, which can be employed for large-scale synthesis of the winning nanoparticles.Finally, our experimental approach will enable us to link biomolecule structure and function. While researchers have for the last 50 years studied biomolecules extracted from biominerals, we still have a very poor understanding of how these control factors such as polymorphism. Here, our diverse libraries are derived from a unique protein scaffold ("adhiron") that exhibits the desirable property of being readily crystallized. Profiting from this ability, we will determine the 3D structure of "winning" proteins, and in comparison with selected "losers", will be able to gain unique insight into the origin of their activity.