This CAREER proposal describes a research plan for the development of a novel plasmon fluctuation spectroscopy and for the application of this sensor to characterize the mechanical properties of individual biopolymers without limitation in observation time. Plasmon coupling spectroscopy utilizes the distance-dependent near-field coupling between individual noble metal nanoparticles to quantify structural fluctuations in individual biopolymers in the frequency domain. The proposal also contains a strong educational component describing plans for training graduate and undergraduate students, as well as attracting high-school students to the natural sciences.
Intellectual Merit. To date, plasmon coupling between individual pairs of noble metal nanoparticles, so called plasmon rulers, has been exclusively used for distance measurements in the time domain. In this application the method is further enhanced to exploit the distance dependence near-field interactions between individual noble metal nanoparticles to characterize structural fluctuations in the biopolymer tether in the frequency domain. To achieve the transition from a time to a frequency domain analysis, the proposed project will develop a new generation of plasmon rulers, detection approaches, and analysis schemes. The distance dependent plasmon coupling in this new generation of plasmon rulers will be systematically mapped, providing new insights into the underlying electromagnetic interactions between noble metal nanoparticles on length scales between 0.5 - 30 nm. The resulting technology will be able to analyze structural fluctuations in short (0.5 nm - 30 nm) DNAs and RNAs without the need to apply an external force. The targeted dynamic distance range is difficult to address with other sensors but is biologically highly relevant. Plasmon fluctuation spectroscopy's ability to monitor structural fluctuations in this range with high temporal resolution without limitation in total observation time will enable improved insights into the mechanical properties of DNAs and RNAs on the single molecule level and how these properties change as consequence of nucleoprotein complex formation. Broader Impact. Plasmon fluctuation spectroscopy enables the analysis of structural dynamics in individual biopolymers with higher temporal resolution and longer observation time than with fluorescence-based approaches. The technique will be applied to probe the mechanical properties of the nucleoprotein complex of the respiratory syncytial virus (RSV) to reveal the virus' fundamental regulation transcription and replication principles. RSV is the most common cause of bronchiolitis among infants and molecular understanding of its transcription and translation can pave the way to improved therapeutics and diagnostics. In addition to scientific impact, this CAREER plan will also have clear educational and outreach benefits. The project will offer high-school, undergraduate and graduate students the opportunity to participate in a collaborative research and education program. The interdisciplinary subject area of the proposed effort is of great interest to the general public. Synergistically with the laboratory research, the plan will enable a substantial outreach through the Principal Investigator's annual "NanoCamp" for students from local inner city high schools (whose students come primarily from underrepresented groups). The aim of the hands-on, week-long "camp" is to enable students to experience the excitement of nanotechnology in particular and of science in general. The Principal Investigator will sponsor undergraduate students and interested high school students who have completed NanoCamp to obtain hands-on research experience in the proposed interdisciplinary research effort.
