New dye could open the door to in vivo applications of fluorescence anisotropy

Feb 17, 2012

(PhysOrg.com) -- US scientists have synthesized a polymethine dye that can be used for fluorescence anisotropy imaging in the near-infrared (NIR) spectral range, making new in vivo applications of this technique possible. Until now, the method has been limited to the visible part of the spectrum, mainly being used in drug selection and quality control of protein labeling. "Due to the deep penetration of near-infrared photons in biological tissues, fluorescence anisotropy could now be potentially utilized to monitor the behavior of drugs in living organisms", says Professor Mikhail Y. Berezin (Washington University), one of the authors of the work published in ChemPhysChem.

Fluorescence anisotropy - also known as fluorescence polarization - is an widely applied in biochemistry and . It uses polarized light to measure the rotation of molecules in solutions. Large molecules, such as proteins, rotate slower than small molecules, and hence show larger fluorescence anisotropy values. NIR probes which absorb and emit light within the range from 700-900 nm have several benefits in biological studies, including reduced interference from endogenous fluorophores and lowered hindrance from light scattering encountered with screening.

"While in theory the method can be applied to a fluorophore in any spectral range, fluorescence anisotropy has long been limited to a visible part of the spectrum", Berezin explains. "Although this limitation was in part due to a poor sensitivity of existing detectors to near-infrared photons, the major challenge lied in the absence of an appropriate fluorophore", he says. According to the author, commercially available NIR probes, such as Cy7 and IR800CW, have relatively long linkers, which leads to incomplete of the fluorescent probe on the of interest and therefore to a higher local mobility - or "wobbling" - of the fluorophore (propeller effect).

To overcome this problem, the team synthesized a new NIR fluorescent label with the desired photophysical properties. They demonstrated that the polymethine dye LS601 has all the required properties to be used as an appropriate label in anisotropy applications. It exhibits a relatively long fluorescence lifetime, a short linker to minimize the low local mobility and can be easily conjugated to biomolecules under aqueous conditions. "Based upon our results we believe that fluorescence anisotropy in the NIR range will find a number of applications in drug discovery, fluorescence polarization imaging and contrast-agent development", the researchers report.

Explore further: Novel 'butterfly' molecule could build new sensors, photoenergy conversion devices

More information: Mikhail Y. Berezin, Defining a Polymethine Dye for Fluorescence Anisotropy Applications in the Near-Infrared Spectral Range, ChemPhysChem, Permalink to the article: dx.doi.org/10.1002/cphc.201100916

add to favorites email to friend print save as pdf

Related Stories

The Dye with the Pumpkin Cuff

Jun 20, 2005

Complexation with a large cuff-shaped molecule stabilizes rhodamine dye fluorescence When irradiated, fluorescent dyes emit light at a different wavelength; for scientists and engineers, these dyes are extremely important aide ...

Near infrared fluorescence lights up hidden blood clots

Jun 06, 2011

Research presented at SNM's 58th Annual Meeting may mark the expansion of a novel imaging agent for an optical technique called near-infrared fluorescence (NIRF), which uses light energy to glean information about cells and ...

Contrast Agent Trials in Swine

Oct 15, 2007

Mammography continues to be the method of choice for the early detection of breast cancer. However, because this technique is not as selective or specific as one would wish, and does not deliver reliable results for every ...

Recommended for you

Team pioneers strategy for creating new materials

Aug 29, 2014

Making something new is never easy. Scientists constantly theorize about new materials, but when the material is manufactured it doesn't always work as expected. To create a new strategy for designing materials, ...

Plug n' Play protein crystals

Aug 29, 2014

Almost a hundred years ago in 1929 Linus Pauling presented the famous Pauling's Rules to describe the principles governing the structure of complex ionic crystals. These rules essentially describe how the ...

Protein glue shows potential for use with biomaterials

Aug 28, 2014

Researchers at the University of Milan in Italy have shown that a synthetic protein called AGMA1 has the potential to promote the adhesion of brain cells in a laboratory setting. This could prove helpful ...

User comments : 0