CELL BIOLOGY: Unprecedented dynamics measurement with 3-D plasmon rulers

Three-dimensional plasmon rulers, developed by a multinational research team, promise to reveal in unprecedented detail such biologic events as the interaction of DNA with enzymes, protein folding, peptide motion, and cell membrane vibration.

Based on coupled plasmonic oligomers in combination with high-resolution plasmon spectroscopy, the approach “enables us to retrieve the complete spatial configuration of complex macromolecular and biological processes,” and to track their dynamic evolution, says Paul Alivisatos, director of U.S. Department of Energy’s Lawrence Berkeley National Laboratory, who led the team of scientists at Berkeley Lab and the University of Stuttgart, Germany.

According to Alivisatos, two noble metallic nanoparticles in close proximity will couple through their plasmon resonances to generate a light-scattering spectrum that depends strongly on the distance between them. This effect has enabled linear plasmon rulers to measure nanoscale distances in cells.

In this animation of a 3-D plasmon ruler (see http://www.youtube.com/watch?v=dgdWrMaAxd4), the plasmonic assembly acts as a transducer to deliver optical information about the structural dynamics of an attached protein. (Image courtesy of Sven Hein, University of Stuttgart)

Compared to other types of molecular rulers, based on chemical dyes and fluorescence resonance energy transfer (FRET), plasmon rulers do not blink or photobleach, and offer exceptional photostability and brightness—but until now could measure distances only along one dimension.

According to researcher Laura Na Liu, the key to success was the ability “to create sharp spectral features in the otherwise broad resonance profile of plasmon-coupled nanostructures by using interactions between quadrupolar and dipolar modes.” Typical dipolar plasmon resonances are broad because of radiative damping, and the simple coupling between multiple particles produces indistinct spectra not easily converted into distances. She and her co-authors overcame this problem with a 3-D ruler constructed from five gold nanorods of individually controlled length and orientation, in which one nanorod is placed perpendicular between two pairs of parallel rods to form a structure that resembles the letter H.

“The strong coupling between the single nanorod and the two parallel nanorod pairs suppresses radiative damping and allows for the excitation of two sharp quadrupolar resonances that enable high-resolution plasmon spectroscopy,” Liu says. “Any conformational change in this 3-D plasmonic structure will produce readily observable changes in the optical spectra.”

The spatial freedom afforded its five nanorods also enables determination of the direction and magnitude of structural changes.

The scientists envision that 3-D plasmon rulers could attach, through biochemical linkers, to a sample macromolecule, for example, to various points along a strand of DNA or RNA—or at different positions on a protein or peptide. The sample macromolecule would then be exposed to light and the optical responses of the 3-D plasmon rulers would be measured via dark field microspectroscopy.

1. N. Liu et al., Science 332 (6036), 1407–10 (2011).

More BioOptics World Current Issue Articles
More BioOptics World Archives Issue Articles

Get All the BioOptics World News Delivered to Your Inbox

Subscribe to BioOptics World Magazine or email newsletter today at no cost and receive the latest news and information.

 Subscribe Now

Get All the BioOptics World News Delivered to Your Inbox

Subscribe to BioOptics World Magazine or email newsletter today at no cost and receive the latest news and information.

 Subscribe Now
Related Articles

Fluorescence expands swallowable camera capsule's cancer detection capabilities

Fluorescent light expands the diagnostic capabilities of a swallowable camera capsule for throat and gut cancer detection.

Spectral microscopy captures metal-labeled neurons in 3D, and with unprecedented detail

A team of researchers used spectral confocal microscopy to image tissues impregnated with silver or gold.

LuxCath optical tissue characterization catheter enables real-time monitoring during cardiac ablation

A study used optical tissue characterization technology for the first time in procedures to treat arrhythmia patients.

EUV spectral imaging tool can map cell composition in 3D

A newly developed spectral imaging instrument enables observation of how cells respond to new medications at a minute level.

Fluorescence Imaging: Optical filtering basics for life sciences

Optical filters can have a dramatic effect on outcomes in life sciences. These principles demonstrate how next-generation thin film enhances excitation and emission in fluorescence bioimaging syste...

Photoacoustics/Biomedical Imaging: Photoacoustic imaging progresses toward medical diagnostics

Recent technological developments in laser and transducer hardware, contrast agents, and image reconstruction algorithms have helped to advance photoacoustic (or optoacoustic) imaging.  

Translational Research: Bench-to-bedside: Progress, pioneers, and 21st Century Cures

The NIH/SPIE Biophotonics from Bench to Bedside workshop (Sept. 24-25) featured speakers and posters presenting exciting translational research in technologies and applications.

Legislation promises biophotonics opportunities

The 21st Century Cures Act (H.R. 6) was a focal point at the NIH/SPIE Biophotonics from Bench to Bedside workshop.

Zeiss partners with Molecular Imaging Platform at McGill University Health Centre

Zeiss has entered into a partnership with the Research Institute of the McGill University Health Centre's Molecular Imaging Platform.


Neuro15 exhibitors meet exacting demands: Part 2

Increasingly, neuroscientists are working with researchers in disciplines such as chemistry and p...

Why be free?

A successful career contributed to keeping OpticalRayTracer—an optical design software program—fr...

LASER Munich 2015 is bio-bent

LASER World of Photonics 2015 included the European Conferences on Biomedical Optics among its si...

White Papers

Understanding Optical Filters

Optical filters can be used to attenuate or enhance an image, transmit or reflect specific wavele...

How can I find the right digital camera for my microscopy application?

Nowadays, image processing is found in a wide range of optical microscopy applications. Examples ...



Twitter- BioOptics World

Copyright © 2007-2015. PennWell Corporation, Tulsa, OK. All Rights Reserved.PRIVACY POLICY | TERMS AND CONDITIONS