Plasmon Rulers as Dynamic Molecular Rulers in Enzymology
Department of Chemistry, The Photonics Center, Boston University, Boston, Massachusetts, USA.Methods in enzymology (Impact Factor: 2.09). 01/2010; 475:175-98. DOI: 10.1016/S0076-6879(10)75008-4
This chapter provides an introduction to the concept of "plasmon rulers," pairs of biopolymer-linked tethered nanoparticles which act as nonblinking, nonbleaching rulers for dynamic molecular distance measurements. Plasmon rulers utilize the distance dependence of the plasmon coupling between individual noble metal particles to measure distances. Although the plasmon ruler approach is still an emerging technology, proof-of-principle experiments have demonstrated that plasmon rulers can already be used to investigate structural fluctuations in nucleoprotein complexes, monitor nuclease catalyzed DNA or RNA cleavage reactions, and detect DNA bending. The physical concepts underlying plasmon rulers are summarized, and effective assembly approaches as well as recent applications are discussed. Plasmon rulers are a useful addition to the single molecule biophysics toolbox, since they allow single biomolecules to be continuously monitored for days at high temporal resolutions.
Article: Nanoparticles in Measurement Science[Show abstract] [Hide abstract]
ABSTRACT: This review describes recent advances in the use of nanoparticles (NPs) for analytical measurements. Over the past decade, the field of nanotechnology has undergone tremendous developments, resulting in new procedures for the controlled synthesis of a wide variety of nanoscale materials and measurement of their unique properties. These properties, including optical, electronic, magnetic, chemical, mechanical, and catalytic, can often be tuned by the size, shape, and composition of the nanostructure. These unique properties and their generally high surface-to-volume ratio has led to their use in several analytical applications. With the widespread use of nanostructures for analytical applications, it is important to review some of the most recent and exciting advances. This review covers the time period of January 2010 to November 2011.Analytical Chemistry 12/2011; 84(2):541-76. DOI:10.1021/ac203233q · 5.64 Impact Factor
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ABSTRACT: This report describes a critical evaluation of silver nanorod arrays as substrates for assaying nucleic acid hybridization by surface enhanced Raman scattering (SERS). SERS spectra acquired on complimentary oligos, alone or in combination, contain the known spectral signatures of the nucleotides that comprise the oligo; however, no signature bands characteristic of the hybrid were observed. Spectra acquired on an oligo with a 5'- or 3'-thiol were distinctly different from that acquired on the identical oligo without a thiol pendant group suggesting a degree of control over the orientation of the oligo on the nanorod surface. A set of oligos consisting of adenine tracts in a polycytosine chain served as molecular rulers to probe the distance dependence of the SERS enhancement. Using these, we have identified the point at which the characteristic bands for the nucleotides that comprise the oligo disappear from the spectrum. These findings suggest that the applicability of SERS for label-free detection of nucleic acid hybridization is limited to short oligos of less than nine nucleotides.Analytical Chemistry 12/2012; 85(3). DOI:10.1021/ac302454j · 5.64 Impact Factor
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ABSTRACT: The ability of two, scattering gold nanoparticles (GNPs) to plasmonically couple in a manner that is dependent on the interparticle separation has been exploited to measure nanometer-level displacements. However, despite broad applicability to monitoring biophysical dynamics, the long time scales (<5Hz) with which plasmonic coupling are typically measured are not suitable for many dynamic molecular processes, generally occurring over several milliseconds. Here, we introduce a new technique intended to overcome this technical limitation: ratiometric analysis using monochromatic, evanescent darkfield illumination (RAMEDI). As a proof-of-principle, we monitored dynamic, plasmonic coupling arising from the binding of single biotin- and neutravidin-GNPs with a temporal resolution of 38 ms. We also show that the observable bandwidth is extendable to faster timescales by demonstrating that RMAEDI is capable of achieving a signal-to-noise ratio greater than 20 from individual GNPs observed with 200 Hz bandwidth.Analytical Chemistry 04/2013; 85(10). DOI:10.1021/ac4004453 · 5.64 Impact Factor
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