The method might be used to take images of diseased tissues by inserting a cargo of fluorescent molecules into tumors that are ordinarily too small to be detected, said Demir Akin, a research assistant professor of biomedical engineering who specializes in nanomedicine.
"These bacteria can potentially deliver specific molecules into a variety of cells," said Akin, the first author of a research paper appearing online this week in the journal Nature Nanotechnology.
Experiments were carried out in cultures of human cancer cells, including intestinal, oral, liver, ovarian and breast cancer cells. The researchers also tested their method on live mice and showed how the technique could be used to deliver specific genes to various organs, including the liver and kidneys.
"The cells in the organs receiving the bacteria with nanoparticles made the intended therapeutic proteins and emitted a light similar to a firefly's glow," Akin said.
Certain bacteria are naturally programmed to dissolve vesicle membranes, a critical step to delivering the cargo. The nanoparticles are referred to as "smart" because they release their cargo at precisely the right moment after entering the cell.
"At the same time that the bacteria are breaking up this vesicle membrane, the cargo dislodges from the bacteria, which are both crucial steps in delivering this cargo," Akin said.
The nanoparticles, which range in size from 40 to 200 nanometers - or billionths of a meter - are attached to the bacteria with "linker molecules."
"The use of commercially available polystyrene nanoparticles makes this delivery system much simpler to implement than previous alternatives," Bashir said.
This new delivery system also is more efficient than other experimental techniques using viruses and bacteri