Switchable, glowing molecules promising for fluorescent probes

Scientists at the University of Miami college of Arts and Sciences have developed a method of switching fluorescent molecules on and off within aqueous environments, strategically trapping the molecules inside water-soluble particles and controlling them with ultraviolet (UV) light.

Live cells incubated with the polymer nanoparticles. The green color is the fluorescence coming from the molecules trapped within the nanoparticles
Live cells incubated with the polymer nanoparticles. The green color is the fluorescence coming from the molecules trapped within the nanoparticles

Scientists at the University of Miami college of Arts and Sciences (Miami, FL) have developed a method of switching fluorescent molecules on and off within aqueous environments, strategically trapping the molecules inside water-soluble particles and controlling them with ultraviolet (UV) light. The work could lead to development of better fluorescent probes for biomedical research.

The scientists created a fluorescent photoswitchable system that is more efficient than current technologies, says Francisco Raymo, professor of chemistry and principal investigator of the study. He explains that his research team's fluorescent switches can be operated in water efficiently, offering the opportunity to image biological samples with resolution at the nanometer level.

Fluorescent molecules are not water soluble; therefore, Raymo and his team created their system by embedding fluorescent molecules in synthetic water-soluble nanoparticles called polymers that enable them to penetrate living cells. Once inside the cell, the fluorescence of the molecules trapped within the nanoparticles can be turned on and off via UV light.

Live cells incubated with the polymer nanoparticles. The green color is the fluorescence coming from the molecules trapped within the nanoparticlesLive cells incubated with the polymer nanoparticles. The green color is the fluorescence coming from the molecules trapped within the nanoparticles
Live cells incubated with the polymer nanoparticles. The green color is the fluorescence coming from the molecules trapped within the nanoparticles. (Image courtesy of Francisco Raymo/University of Miami College of Arts and Sciences)

The new system is faster and more stable than current methods. The fluorescent molecules glow when exposed simultaneously to UV and visible light and revert back to their original non-luminous state in less than 10 microseconds after the UV light is removed.

By using engineered synthetic molecules, the new system is able to overcome the natural wear-down process that organic molecules are subject to when exposed to UV light.

"The system can be switched back and forth between the fluorescent and non-fluorescent states for hundreds of cycles, without sign of degradation," Raymo says.

The surface of the system can be customize to help it attach to specific molecules of interests, thus allowing researchers to visualize structures and activity within cells, in real time, with unprecedented resolution.

Raymo and his research team will continue improving the properties of the molecules for future biomedical applications.

The findings are published online by the Chemistry-A European Journal; for more information, please visit http://onlinelibrary.wiley.com/doi/10.1002/chem.201201184/abstract;jsessionid=7ED188423718ACDD0B09DB540A329DE3.d03t03.

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