Plasmon coupling based single-molecule biosensors
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Abstract
The understanding of many important biological systems requires tools that allow for dynamic nanoscale distance monitoring and single-molecule resolution. Proteins binding to nucleic acids and cell surface receptor oligomerization are examples of biopolymer interactions that occur at length scales below the diffraction limit of -are not very bright. Therefore, the development of alternative tools with improved spacial and temporal resolution for the application to single molecule biology studies is highly desirable.
One such tool is based on the plasmon coupling of discrete pairs of noble metal nanoparticles (plasmon rulers). The signal from plasmon rulers is based on scattering, so they are photophysically stable and are significantly brighter than fluorescent dye molecules. The plasmons of nearby nanoparticles couple in a distance dependant manner. As particles approach each other within one diameter's length, their scattering signal increases and the wavelength of the scattered light red-shifts exponentially with decreasing interparticle distance.
As a first application to RNA, plasmon rulers were applied to study the modulation of RNA-enzyme interactions by spermidine, a polycation. This study showed that spermidine induces the transient stabilization of secondary structures within RNA, as evidenced by discrete subpopulations of cleavage times in the presence of the single-strand specific enzyme, RNase A. The optical response of RNA tethered plasmon rulers results in polarization of the scattered light along the long dimer axis. Analysis of changes in polarization in both the time and frequency scale allowed for the characterization of dimer motion (implying states of the RNA tether). Plasmon rulers are also attractive tools for applying to the study of receptor clustering on the surface of live cells. To enable these studies a novel method for the preparation of stable, antibody functionalized silver nanoparticles based on gel matrix confinement was developed.
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Thesis (Ph.D.)--Boston University
PLEASE NOTE: Boston University Libraries did not receive an Authorization To Manage form for this thesis or dissertation. It is therefore not openly accessible, though it may be available by request. If you are the author or principal advisor of this work and would like to request open access for it, please contact us at open-help@bu.edu. Thank you.
PLEASE NOTE: Boston University Libraries did not receive an Authorization To Manage form for this thesis or dissertation. It is therefore not openly accessible, though it may be available by request. If you are the author or principal advisor of this work and would like to request open access for it, please contact us at open-help@bu.edu. Thank you.