Ultrasensitive Imaging Using Gold-Silver Nanocages

Researchers at Purdue University and Washington University have developed an experimental ultrasensitive medical imaging technique that uses a pulsed laser and tiny metallic nanocages. The system works by shining near-infrared femtosecond laser pulses through the skin to detect hollow nanocages and solid nanoparticles – made of an alloy of gold and silver – that have been injected into the bloodstream. The gold-silver nanocages exhibit a bright three-photon luminescence when excited by the ultrafast pulsed laser, with 10-times greater intensity than pure gold or silver nanoparticles.
The signal allows live cell imaging with negligible damage from heating, this in contrast with previous approaches that rely on tiny metallic nanorods and nanospheres where heat is a major problem. The imaging technology provides brightness and contrast potentially hundreds of times better than conventional fluorescent dyes used for a wide range of biological imaging to study the inner workings of cells and molecules. Findings were published online April 6 in the journal Angewandte Chemie’s International Edition.
Purdue press statement: Ultrasensitive imaging method uses gold-silver ‘nanocages’…
Abstract: Bright Three-Photon Luminescence from Gold/Silver Alloyed Nanostructures for Bioimaging with Negligible Photothermal Toxicity