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: Infrared light puts malaria to the test

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

Computer program could help solve arson cases

5 hours ago

Sifting through the chemical clues left behind by arson is delicate, time-consuming work, but University of Alberta researchers teaming with RCMP scientists in Canada, have found a way to speed the process.

User comments : 0

More news stories

Computer program could help solve arson cases

Sifting through the chemical clues left behind by arson is delicate, time-consuming work, but University of Alberta researchers teaming with RCMP scientists in Canada, have found a way to speed the process.

Genetic code of the deadly tsetse fly unraveled

Mining the genome of the disease-transmitting tsetse fly, researchers have revealed the genetic adaptions that allow it to have such unique biology and transmit disease to both humans and animals.

Ocean microbes display remarkable genetic diversity

The smallest, most abundant marine microbe, Prochlorococcus, is a photosynthetic bacteria species essential to the marine ecosystem. An estimated billion billion billion of the single-cell creatures live i ...