Nanotechnology of fluorescent proteins in a lipid/polymer matrix: soft thin film materials for artificial photosynthesis

近年来，全球太阳能发电量从2009年的19 TWh迅速增加到2019年的724 TWh，这表明它将成为我们未来能源供应的关键部分。随着我们达到传统光合作用的效率极限，人们对生物启发的纳米技术重新产生了兴趣，包括“人工光合作用”的可能性。自然界已经进化出一套光敏纳米机器，即在含有高浓度叶绿素色素的叶绿体中发现的所谓“捕光”（LH）蛋白。该项目将采用“生物启发”的方法，将合成染料分子与从菠菜中提取的LH蛋白结合，并将其置于精心设计的软薄膜中。脂质是薄膜的理想软材料：它们容易自组装成稳定的纳米级双层，并具有可调的物理和化学性质。然而，脂质本质上是“脂肪”分子，并且易于快速氧化降解。通过将不同类型的脂质与脂质的两亲性合成聚合物混合，我们将设计具有预定粘度、电荷和特定反应基团的膜，并且重要地增加稳健性和延长膜寿命。由聚（环氧乙烷）和聚（丁二烯）组成的短的二嵌段共聚物已经显示出稳定膜蛋白，使得蛋白质保持其活性数月而不是几天。初步数据表明，集光蛋白在这些聚合物中也很稳定，因此，这可能成为人工光合作用的更稳定平台。该项目的目标是开发脂质/聚合物膜，以提高光合蛋白在各种物理压力下的稳定性。通过系统地测试脂质饱和度和链长、聚合物与脂质和蛋白质与脂质的比率的影响，将改变膜的性质。将在温度和pH值范围内评估稳定性，以指导优化工艺。我们还将利用我们对更奇特的脂质行为的了解来设计一种脂质系统，该系统将自发地自组装成堆叠的多层排列，从而增加蛋白质密度和光捕获效率。脂质-聚合物-蛋白质纳米复合材料将使用世界一流的技术套件进行表征，包括先进的光谱学和显微镜。原子力显微镜（AFM）将用于绘制微米至纳米级薄膜的三维形貌和机械性能，荧光显微镜将用于可视化从毫米到纳米级的膜的动态重排。差示扫描量热法和/或荧光相关光谱法将量化相对于温度的相变。单分子荧光光谱法如FLIM-FRET将用于测量脂质/聚合物和蛋白质之间的扩散速率和特定相互作用，以评估它们的混合行为。该项目的成功将提供新的纳米材料，可用于未来的人工光合作用装置，例如，作为生物光电化学电池中的涂层。该项目将支持未来开发使用生物成分或生物启发设计原则的太阳能纳米技术。我们现在为理解生物物理机制所做的工作可以使我们将生物分子或无机材料与设备（例如光敏薄膜）连接起来。将启动与行业的接触，以了解太阳能技术部门的需求，并在以贸易为重点的活动（如太阳能贸易协会）中进行接触。这将为未来的项目和与工业界的伙伴关系奠定基础，例如评估利用生物或生物启发组件的染料敏化太阳能电池的经济可行性。

Solar generation of electricity has rapidly increased in recent years from 19 TWh in 2009 to 724 TWh globally in 2019, suggesting that it will be a critical part of our future energy supply. As we are reaching the efficiency limits of traditional photovoltaics, there has been renewed interest in bio-inspired nanotechnologies, including the possibility of "artificial photosynthesis". Nature has evolved a suite of photo-active nano-machines, the so-called "light-harvesting" (LH) proteins found in chloroplasts which contain high concentrations of chlorophyll pigments. This project will apply a "bio-inspired" approach where we incorporate synthetic dye molecules with LH proteins extracted from spinach and place them within carefully designed soft thin films.Lipids are an ideal soft material for thin-films: they readily self-assemble into stable nanoscale bilayers and have tunable physical and chemical properties. However, lipid are essentially "fat" molecules, and prone to rapid oxidative degradation. By mixing different types of lipid with amphiphilic synthetic polymers of lipid, we will design a film which has a pre-determined viscosity, charge and specific reactive groups, and importantly increased robustness and extended membrane lifetime. A short diblock copolymer comprised of poly(ethylene oxide) and poly(butadiene) has been shown to stabilize membrane proteins so that the proteins keep their activity for many months rather than a few days. Preliminary data suggests that Light Harvesting proteins are also stable in these polymers, therefore, this could become a more stable platform for artificial photosynthesis.The objectives of this project are to develop lipid/polymer membranes that increase the stability of photosynthetic proteins under various physical stresses. The film properties will be varied by systematically testing the effect of the lipid saturation and chain length, the ratio of polymer-to-lipid and protein-to-lipid. Stability will be assessed across a range of temperatures and pH and to guide the optimization process. We will also exploit our knowledge of more exotic lipid behaviour to design a lipid system that will spontaneously self-assemble into a stacked multi-layer arrangement, thereby increasing protein density and light harvesting efficiency. The lipid-polymer-protein nanocomposites will be characterized using a world-class suite of techniques, including advanced spectroscopy and microscopy. Atomic Force Microscopy (AFM) will be used to map the 3-D topography and mechanical properties of the thin films at the micro- to nanoscale and fluorescence microscopy to visualize the dynamic rearrangements of membranes at scales from millimetres to nanometres. Differential Scanning Calorimetry and/or Fluorescence Correlation Spectroscopy will quantify the phase transitions against temperature. Single-molecule fluorescence spectroscopy such as FLIM-FRET will be used to measure the rates of diffusion and specific interactions between lipids/polymers and proteins to assess their mixing behaviours. The success of this project will provide new nanomaterials which could be applied in future artificial photosynthesis devices, e.g., as coating in bio-photo-electrochemical cells. This project would support the future development of solar nanotechnologies which use biological components or bio-inspired design principles. What we do now to understand biophysical mechanisms could allow us to interface biomolecules or inorganic materials with devices (e.g. photo-active thin films). Engagement with industry will be initiated to understand the needs of the solar technologies sector and make contacts at trade-focused events (e.g. Solar Trade Association). This will prepare the ground for the future project and partnerships with industry, e.g. assessing the economic feasibility of dye-sensitized solar cells exploiting biological or bio-inspired components.