Charge transfer at abiotic-biotic interface for photosynthetic biohybrids

该奖项是与ENG/CBET电化学系统项目共同资助的。光合生物杂交体在非生物-生物界面的电荷转移。非技术总结快速发展的工业世界需要创造性和可持续的策略来处理单向碳循环。将二氧化碳转化为太阳能驱动的增值产品是一个理想的解决方案。将单细胞微生物与捕光纳米材料结合到光合生物杂交系统（PBS）中是一种很有前途的方法。生物微生物利用一系列酶和还原途径从简单的构件（包括CO2、N2和H2O）生产长链烃。半导体纳米材料具有高度可配置性，具有可调的宽带光吸收和表面电荷，与微生物配对良好，能够捕获大量阳光，从而实现太阳能到化学转化。这些光合生物混合物提高了生物全细胞催化剂和半导体纳米材料的最佳功能。然而，在这些新兴的光合生物杂交的基本电子转移和能量转导途径仍然在很大程度上未被探索，由于生物/非生物半导体/细菌界面的复杂性。本项目的目的是研究这种能量转换途径，从半导体纳米结构吸收太阳光开始，电子产生并从半导体转移到微生物，然后利用转移的电子由微生物还原CO2。通过将化石燃料燃烧的主要副产物CO2还原为使用可再生能源的增值燃料（即，太阳能和人工光合作用），可以帮助关闭碳排放循环，减少二氧化碳排放，使我们的社会更具可持续性。从光合生物杂交系统产生的简单分子开始，可以构建更复杂的物质，如肥料，工业和商品化学品，聚合物和药物等，所有这些都源于捕获大气CO2。与研究工作相结合，PI还提出了一个教育项目，激励和准备大学预科学生在材料科学和能源研究的职业生涯，包括在当地中学的推广工作（湾区科学家在学校，和夏季STEM实习）。技术总结液体阳光代表了一种新形式的化学能转换和储存在化学键从太阳能。光合生物杂交产生液体阳光通过“光子进入，化学键出”的材料/生物界面，可以通过时空成像和光谱分析进行探测。光合生物杂交系统（PBS）联合收割机结合了生物全细胞催化剂和半导体纳米材料的最佳属性。包裹在其天然细胞环境中的酶机制提供了精致的产物选择性和低底物活化屏障，而半导体纳米材料比生物分子更稳定且更有效地收集光能。最近，它已被证明，收集的增值化学品，如液体燃料，可生物降解的聚合物，和其他复杂的天然产品，可以直接从二氧化碳使用这些光合生物杂交生产。然而，在这些新兴的光合生物杂交系统中的基本电子转移和能量转导途径仍然未被探索，由于生物/非生物半导体/细菌界面的复杂性。从根本上说，这些PBS的光合作用功能源于“光子输入，化学键出”的材料/生物界面，其在长度和时间尺度上跨越多个数量级。本研究的目的是通过无机光敏剂界面电荷转移和生物矿化的研究，设计和探索无机-生物人工光合作用模型系统的基本无机-生物界面。该模型系统的研究需要三个阶段：1）阐明光敏剂和Wood-Ljungdahl途径中生物参与者之间的电荷转移; 2）详细研究光敏剂生物矿化和光敏剂-全细胞电荷转移;（3）功能整体的发展-电池光敏系统和筛选矿物前驱体和空穴清除剂对系统生产率的影响。该奖项反映了NSF的法定使命并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

This award is Co-Funded with ENG/CBET Electrochemical Systems programCharge transfer at the abiotic-biotic interface for photosynthetic biohybridsNON-TECHNICAL SUMMARYA rapidly developing industrial world requires creative and sustainable strategies for dealing with the unidirectional carbon cycle. The conversion of CO2 to value-added products powered with solar energy is an ideal solution. Combining single-cell microorganisms with light-harvesting nanomaterials into photosynthetic biohybrid systems (PBS) represents a promising approach. Biological microorganisms engage a collection of enzymes and reductive pathways to produce long-chain hydrocarbons from simple building blocks, including CO2, N2, and H2O. Semiconducting nanomaterials are highly configurable with tunable broadband light absorption and surface charge, pair well with microorganisms and enable significant sunlight capture, hence solar-to-chemical conversion. These photosynthetic biohybrids boost the best functions of biological whole-cell catalysts and semiconducting nanomaterials. However, the fundamental electron transfer and energy transduction pathway in these emerging photosynthetic biohybrids remains largely unexplored due to the complex nature of the biotic/abiotic semiconductor/bacteria interfaces. The purpose of this project is to examine this energy transduction pathway, starting from solar light absorption by the semiconductor nanostructures, electron generation and transfer from the semiconductor to microorganism, and then CO2 reduction by the microorganism using transferred electron. By reducing CO2, the major byproduct of fossil fuel combustion, into value-added fuels using renewable energy sources (i.e., solar energy and artificial photosynthesis), one can help close the carbon emission loop, mitigate CO2 emissions, and make our society more sustainable. Starting from the simple molecules produced by photosynthetic biohybrid systems, more complex substances, like fertilizers, industrial and commodity chemicals, polymers, and pharmaceuticals, among others, can be constructed, all originating from capturing atmospheric CO2. Integrated with the research effort, the PI also proposes an educational project that stimulates and prepares pre-college students for careers in materials science and energy research, including outreach efforts at local middle-high schools (Bay Area Scientists in Schools, and summer STEM internship).TECHNICAL SUMMARYLiquid sunlight represents a new form of chemical energy converted and stored in chemical bonds from solar energy. Photosynthetic biohybrids produce liquid sunlight through a “photon-in, chemical bond-out” materials/biology interface that can be probed through spatiotemporal imaging, and spectroscopic analyses. Photosynthetic biohybrid systems (PBS) combine the best attributes of biological whole-cell catalysts and semiconducting nanomaterials. Enzymatic machinery enveloped in its native cellular environment offers exquisite product selectivity and low substrate activation barriers while semiconducting nanomaterials harvest light energy stably and more efficiently than biomolecules. Recently, it has been demonstrated that a collection of value-added chemicals, such as liquid fuels, biodegradable polymers, and other complex natural products can be directly produced from CO2 using these photosynthetic biohybrids. However, the fundamental electron transfer and energy transduction pathway in these emerging photosynthetic biohybrid systems remains unexplored due to the complex nature of the biotic/abiotic semiconductor/bacteria interfaces. Fundamentally, the photosynthetic function of these PBSs originates from a “photon-in, chemical bond-out” materials/biology interface that spans multiple orders of magnitude both in the length and time scale. The objective of this research is to design and explore the fundamental abiotic-biotic interfaces of a model system for inorganic-biological artificial photosynthesis through studies on interfacial charge transfer and biogenic mineralization of inorganic photosensitizers. This model system study will require three phases: 1) elucidation of charge transfer between photosensitizers and biological participants in the Wood-Ljungdahl Pathway; 2) a detailed study of photosensitizer biomineralization and photosensitizer-whole cell charge transfer; and 3) development of a functional whole-cell photosensitized system and screening the effects of mineral precursor and hole scavenger on system productivity.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.