Nanocantilevers image nanoparticles in cells

Jul 9 2008

Borrowing from a Nobel Prize-winning technique credited with starting the nanotechnology revolution, a team of researchers from Oak Ridge National Laboratory (ORNL) and Northwestern University's Nanomaterials for Cancer Diagnostics and Therapeutics has developed a method for imaging nanoparticles inside of cells.

This technique should prove useful for studies of nanomaterials toxicology as well as those designed to improve nanoparticle-based drug delivery. This work has been published online in advance of print publication in the journal Nature Nanotechnology.

Ali Passian, Ph.D., and his colleagues at ORNL teamed with a research group headed by Vinayak Dravid, Ph.D., at Northwestern to probe the fate of individual nanoparticles inside of cells. Dravid and colleague Gajendra Shekhawat, Ph.D., had earlier developed a modified form of scanning electron microscopy, the Nobel Prize-winning invention, that uses nanoscale cantilevers as ultrasonic probes that can create a holographic image of a rapidly vibrating soft object lying beneath the cantilever as it scans that object. This new form of nanometer-resolution microscopy is known as scanning near-field ultrasonic holography, or SNFUH, and Dravid's research group has used it to generate detailed three-dimensional maps of soft objects.

Making use of SNFUH, Passian and his collaborators examined various cells taken from mice a week after the animals had been exposed to aerosolized nanoparticles known as single-walled carbon nanohorns, which are closely related to carbon nanotubes. Images of lung macrophages clearly revealed the exact location of individual nanohorns within the cells. The researchers also imaged nanohorns present inside red blood cells taken from the bloodstream, demonstrating that the nanohorns escape the lung and enter the circulatory system.

This work is detailed in the paper "Imaging Nanoparticles in Cells by Nanomechanical Holography." An abstract of this paper is available at the journal's Web site. View abstract