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Monday, 2nd November 2009 (633 views)

Gold has been used to create a microscopic nanocage that could be used in a "smart" drug delivery system.

Dr Younan Xia and his team at Washington University in St Louis used gold because at the nanoscale, it responds to light.

By adjusting the thickness of the cage walls, the scientists were able to "tune" its colour from red to purple, bright blue, dark blue and wavelengths near the infrared.

When the cage absorbs light in this wavelength, it is converted to heat. A special polymer coating the nanocage's walls responds to heat, so that when it is below a critical temperature, the polymer chains act like brushes standing out from cage, trapping the nanocage's cargo inside. Above this critical temperature and the polymer chains shrink together, opening the cage and letting its contents out.

Dr Xia and his team filled the nanocages with red dye and successfully released it by heating the particles with a near-infrared laser. They subsequently loaded the cages with the chemotherapy drug doxorubicin and successfully released it, killing breast cancer cells growing in wells on a plastic plate.

Last week, Nanowerk reported that Professor Stephen Lippard of the Massachusetts Institute of Technology and Dr Chad Mirkin of Northwestern University had successfully used gold nanoparticles coated with nucleic acid to deliver a non-toxic form of treatment directly to cancer cells.

 

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