Inorganic Biological Hybrid Systems for Photochemical Biosynthesis

能源和环境问题是本世纪人类面临的最大挑战之一。尽管为开发可再生能源做出了巨大努力，但所使用的大部分能源仍然来自不可再生的化石燃料。使用可再生能源输入（即人工光合作用）将二氧化碳（一种丰富的碳源）减少为增值燃料，将使我们能够减少对传统化石燃料的依赖，减少二氧化碳排放，使我们的社会更具可持续性。此外，由二氧化碳生产的化学燃料可以很容易地在当前的能源基础设施中实施，从而允许快速平稳地过渡到可再生能源社会。这项研究旨在解决几个问题：使用半导体纳米晶体收集太阳能电力，用细菌/细菌杂交体合成各种有用的化学物质，以及处理大量产生的麻烦废物，即，二氧化碳.这项研究也是高度跨学科的，因为两种不同技术的融合产生了一个问题的解决方案，即，材料科学生产半导体纳米晶体，以及生物技术利用纳米晶体产生的电子和空穴来生产一般增值化学品。这项研究中获得的见解有可能取代对石油化学路线的依赖，以化学合成燃料，肥料，工业和商品化学品，聚合物，药物等，同时提供了一条通往碳捕获和降低大气CO2水平的道路。技术自然光合作用依赖于一系列捕光蛋白，这些蛋白在光学上限于吸收峰，仅能够利用太阳光谱的相对窄的区域，并且容易受到较高能量光子的损害。相比之下，构成高效商业光伏电池基础的无机固态半导体超过了它们的生物类似物，具有吸收带，在该吸收带之上可以收集所有更高能量的光子用于化学工作。然而，这种无机光捕获方案是相当昂贵的，需要非常高纯度的稀有元素，以及能量密集型合成方案。此外，与其生物对应物不同，许多性能最高的材料从根本上说是不稳定的，容易受到各种损伤和降解途径的影响，没有内置的自我修复机制。人们可能会设想一个混合系统，其中两个世界的最佳组合用于光化学生物合成的目的：无机化学系统的光电特性，与生物系统的合成，自我再生特性。通过这种共生关系，其中每一半都增强了另一半的能力，本研究的目的是设计和探索无机-无机复合材料模型系统的基本生物-非生物界面，利用CO2作为唯一碳源的多种化学产品的生物人工光合作用。该模型系统将需要几个阶段：1）选择用于化学合成的生物组分; 2）选择无机光收集器; 3）探索无机-生物混合系统的协同效应;以及4）详细研究新形成的生物-非生物界面的基本机制。这项拟议中的工作代表了对相对未开发领域的首次尝试：半导体和全细胞微生物之间的能量转导。PI认为这是其同类工作中的第一项工作是检查微生物的自我光敏化，其中细菌能够合成自己的无机半导体光收集器，并通过这种新形式的能量转导进行正常的代谢功能。拟议的工作将作为教学和培养学生在化学，物理，生物和材料工程可再生能源研究的高度跨学科技能的基础。

Non-technicalEnergy and environmental problems represent one of the greatest challenges facing humankind in this century. Despite tremendous efforts to develop renewable energy sources, still the majority of energy used is derived from non-renewable fossil fuels. Reducing carbon dioxide, an abundant carbon source, into value added fuels using a renewable energy input (i.e. artificial photosynthesis) would allow us to reduce our dependence on conventional fossil fuels, mitigate CO2 emissions and make our society more sustainable. Furthermore, chemical fuels produced from carbon dioxide could be readily implemented in the current energy infrastructure allowing a quick and smooth transition toward a renewable energy society. This research is aimed at solving several problems: harvesting solar electricity using semiconductor nanocrystals, synthesizing a variety of useful chemicals with nanocrystal/bacteria hybrids, and disposing of a troublesome waste product produced in very large quantities, i.e., carbon dioxide. This research is also highly cross-disciplinary as the confluence of two disparate technologies to produce a solution to a problem, i.e., materials science to produce semiconductor nanocrystals, and biotechnology to use the electrons and holes produced by the nanocrystals to general value-added chemicals. The insights gained in this study possesses the potential to supplant the reliance on petrochemical routes to chemical synthesis for fuels, fertilizers, industrial and commodity chemicals, polymers, pharmaceuticals, and more, while simultaneously providing a path towards carbon capture and reduction of atmospheric CO2 levels.TechnicalNatural photosynthesis relies upon a series of light harvesting proteins, which are optically limited to an absorption peak, only capable of utilizing a relatively narrow region of the solar spectrum and are susceptible to damage by higher energy photons. In comparison, inorganic, solid-state semiconductors, which form the basis of high efficiency commercial photovoltaic cells, surpass their biological analogues, possessing an absorption band, above which all higher energy photons can be collected for chemical work. However, such inorganic light harvesting schemes are quite costly, requiring scarce elements in exceptionally high purity, and energy intensive synthesis schemes. Additionally, unlike their biological counterparts, many of the highest performing materials are fundamentally unstable, susceptible to a variety of damage and degradation pathways with no built in mechanism for self-repair. One might envision a hybrid system, in which the best of both worlds are combined for the purpose of photochemical biosynthesis: the optoelectronic properties of inorganic chemical systems, with the synthetic, self-regenerative properties of biological systems. Through such a symbiotic relationship, in which each half augments the capabilities of the other, it is possible to design a new type of biotic-abiotic hybrid biomaterial that surpasses the capabilities of their individual components.The objective of this research is to design and explore the fundamental biotic-abiotic interfaces of a model system for inorganic-biological artificial photosynthesis of a diversity of chemical products utilizing CO2 as the sole carbon source. This model system will require several phases: 1) selection of a biological component for chemical synthesis; 2) selection of an inorganic light harvester; 3) exploration of the synergistic effects of the inorganic-biological hybrid system; and 4) detailed study of the fundamental mechanisms at the newly formed biotic-abiotic interfaces. This proposed work represents a first foray into relatively unexplored territory: the energy transduction between semiconductors and whole cell microorganisms. Of what the PI believe to be the first work of its kind is the examination of the self-photosensitization of a microorganism, in which bacteria is able to synthesize its own inorganic semiconductor light harvester, and carry out normal metabolic function through this new form of energy transduction. The proposed work will serve as a foundation for teaching and training students highly interdisciplinary skills in chemistry, physics, biology and materials engineering for renewable energy research.