RUI: Photoelectronic Properties of DNA-Chromophore Hybrids and Porphyrin Nanowires

ID：MPS/DMR/BMAT（7623）1306170 PI：Smith，Walter ORG：Haverford CollegeTitle：- 我知道DNA-发色团杂化物和卟啉染料的光电性能技术：与传统光刻技术相比，自组装分子电路有望大幅降低制造和能源成本，并可能实现全新的功能。 创建复杂的自组装电路需要易于编程和复杂的识别能力;这可以由DNA提供。 对于电子设备，DNA必须传导电荷。 然而，对于大于50 nm的距离，DNA的导电性较差，特别是在干燥状态下。 在这项工作中，将探索和表征增加DNA电导率的方法。 （1）研究通过形成两种类型的DNA/发色团杂化物来赋予DNA长程导电性或光电导性的方法，一种是将卟啉插入碱基堆中，另一种是使用在近紫外吸收的修饰碱基。 (2)改进技术，选择性地将DNA/发色团混合物连接到特定的电极上，这是开发复杂电路的一个要求。 (3)含卟啉的自组装纳米线的光电性能的模型的测试预测，使用4探针测量，测量在真空和可变O2浓度下，和测量使用圆偏振光。 (4)开发在DNA-发色团杂交体中产生三末端连接的方法，并测试杂交体链之间的串扰。 这项工作也集中在纳米线自组装单独从卟啉分子。 这些可能在分子电子学中有应用，包括光捕获。 此外，探测卟啉纳米线可以提供有关DNA/发色团杂化物的基本机制的重要见解。 非技术性：这项工作的结果将有助于为自组装分子电子学的最终真正革命奠定基础。 这一领域正处于需要对基础科学有更深入的理解才能取得进展的阶段。 这项工作将提供开创性的见解，在DNA发色团混合物的导电性（而不是转移单电荷）的物理。 这项研究将首次测量圆偏振光对自组装纳米丝光电特性的影响。 这项工作的结果将激励物理学，物理化学和生物物理学的研究人员。 15名本科生和3名高中生将获得激烈的，前沿的研究经验，包括在仔细的科学实践培训以及子领域的具体培训。 其中约40%将来自物理学代表性不足的群体（女性，非洲裔美国人和拉丁美洲人）。 每个学生将创建一个网页，其中包括视频采访，向公众介绍他/她的研究。 PI将利用他指导79名本科研究生的经验，创建一个网站/wiki，致力于指导物理学本科研究人员，其中包括专门介绍物理学每个子学科的部分。 PI将主持网站的凝聚态部分，将招募其他教师主持其他部分，并将通过包括与物理学本科生研究经验项目的所有协调员进行年度联系在内的方法宣传该网站。 该网站每年都会有许多研究导师咨询，并将为学生的研究效率提供至少10%的提高，相当于所有学生在一年内的数千个工作小时。 此外，灌输给这些学生的习惯应该坚持到研究生院及以后。

ID: MPS/DMR/BMAT(7623) 1306170 PI: Smith, Walter ORG: Haverford CollegeTitle: RUI: Photoelectronic properties of DNA-chromophore hybrids and porphyrin nanowiresTechnical: Self-assembled molecular circuits hold the promise of dramatic reductions in manufacturing and energy costs compared to conventional lithographic techniques, as well as the possibility of completely new functionalities. Creation of complex self-assembled circuits requires an easily programmable and sophisticated recognition capability; this can be provided by DNA. For electronic devices, the DNA must conduct charge. However, for distances longer than 50 nm, the conductivity of DNA is poor, especially in the dry state. In this work, methods for increasing the conductivity of DNA will be explored and characterized. The specific objectives of this work are: (1) Investigate methods of imparting long-range conductivity or photoconductivity to DNA by forming DNA/chromophore hybrids of two types, one with porphyrins intercalated into the base stack and one using modified bases that absorb in the near UV. (2) Refine techniques for selectively attaching the DNA/chromophore hybrids to specific electrodes, a requirement for the development of complex circuits. (3) Test predictions of a model for the photoelectronic properties of porphyrin-containing self-assembled nanowires, using 4-probe measurements, measurements under ultrahigh vacuum and variable O2 concentration, and measurements using circularly-polarized light. (4) Develop methods of creating three-terminal junctions in the DNA-chromophore hybrids, and also test for cross-talk between crossing hybrid strands. The work also focuses on nanowires self-assembled solely from porphryin molecules. These may have applications in molecular electronics, including light harvesting. Furthermore, probing the porphryin nanowires can give important insights about fundamental mechanisms in the DNA/chromophore hybrids. Non-Technical: The results of this work will help to lay the foundations for an eventual true revolution in self-assembled molecular electronics. This field is at the stage where a deeper understanding of the basic science is needed to make progress. This work will provide pioneering insights into the physics of conductivity (as opposed to transfer of single charges) in DNA-chromophore hybrids. This research will include the first measurements of the effects of circularly polarized light on the photoelectronic properties of a self-assembled nanofilament. Results from this work will motivate researchers in physics, physical chemistry, and biophysics. Fifteen undergraduates and three high-school students will get an intense, cutting-edge research experience, including training in careful scientific practice as well as subfield-specific training. About 40% of these will be from groups underrepresented in physics (women, African-Americans, and Latinos). Each student will create a web page including a video interview to present his/her research to the general public. The PI will use his experience from mentoring 79 undergraduate research students to create a website/wiki devoted to mentoring physics undergraduate researchers, with sections devoted to each subdiscipline of physics. The PI will host the condensed matter portion of the website, will recruit other faculty to host the other sections, and will publicize the site by methods including annual contacts with all coordinators of physics 'Research Experience for Undergraduates' programs. This website will be consulted by many research mentors each year, and will provide at least a 10% improvement in the research efficiency of their students, corresponding to thousands of work hours for all the students put together in a single year. Further, the habits instilled in these students should persist through graduate school and beyond.