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

ID: MPS/DMR/BMAT(7623) 1306170 PI: Smith， Walter ORG: Haverford college标题：RUI: dna -发色团杂体和卟啉纳米线的光电子特性技术：自组装分子电路与传统光刻技术相比，有望大幅降低制造和能源成本，以及实现全新功能的可能性。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，对于超过50纳米的距离，DNA的导电性很差，特别是在干燥状态下。在这项工作中，增加DNA电导率的方法将被探索和表征。这项工作的具体目标是：(1)研究通过形成两种类型的DNA/发色团杂合体来赋予DNA远程导电性或光导电性的方法，一种是将卟啉嵌入到基堆中，另一种是使用在近紫外线中吸收的修饰基。(2)改进选择性地将DNA/发色团杂合体连接到特定电极的技术，这是开发复杂电路的必要条件。(3)对含卟啉自组装纳米线的光电特性模型进行了测试预测，包括4探针测量、超高真空和变O2浓度测量以及圆偏振光测量。(4)发展在dna -发色团杂交种中创建三端连接的方法，并测试交叉杂交种链之间的串扰。这项工作还集中在仅由卟啉分子自组装的纳米线上。这些可能在分子电子学中有应用，包括光收集。此外，探测卟啉纳米线可以为DNA/发色团杂交的基本机制提供重要的见解。非技术：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。这个领域正处于需要对基础科学有更深入的了解才能取得进展的阶段。这项工作将为dna -发色团杂合体的电导率物理学（与单电荷转移相反）提供开创性的见解。这项研究将包括圆偏振光对自组装纳米丝光电特性影响的首次测量。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名高中生将获得密集的前沿研究经验，包括仔细的科学实践培训以及子领域特定培训。其中约40%将来自物理学领域未被充分代表的群体（女性、非裔美国人和拉美裔）。每个学生将创建一个包含视频采访的网页，向公众展示他/她的研究。PI将利用他指导79名本科生的经验，创建一个专门指导物理学本科生研究人员的网站/wiki，其中每个分支学科都有专门的部分。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，并将通过与所有本科生物理研究经验项目协调员的年度联系等方式宣传该网站。这个网站每年将被许多研究导师参考，并将为他们的学生提供至少10%的研究效率提高，相当于将所有学生在一年内的数千个工作小时放在一起。此外，灌输给这些学生的习惯应该坚持到研究生院或以后。

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.