Keys in a lock
To better target cancer cells, the UA team attached liposomes to signal molecules called ligands, which interact with specific cell receptors like keys in a lock.
"It all depends on the disease that we're targeting, but in the case of tumor cells, they over-express certain receptors for several reasons. One is tumor cells are proliferating very quickly, and so they're over-expressing a lot of nutrient receptors because they want to divide faster," said Xenia Kachur, a third-year graduate student in the Biomedical Engineering Graduate Interdisciplinary Program, or GIDP. The extra receptors make the liposomes more likely to latch onto and get inside tumor cells than normal cells.
As they degrade, liposomes release drugs bit-by-bit in an uncontrolled fashion, which may not effectively destroy tumor cells. Said Sarah Leung, a fourth-year graduate student in the biomedical engineering GIDP who also is in the Romanowski lab: "There's a particular concentration at which you have optimal results, so below that you don't have enough of the drug to get a good response, and above that it might be even more toxic."
The new invention could allow doctors to control the amount of drug released at a time, and to release the drug only in the tumor region, thereby protecting healthy cells from damage caused by the drug. This is where the gold lining comes in.
Drugs coated in gold
"A property of gold is that it can convert near infrared light into heat," said Kachur. "By putting gold on the surface of these liposomes, we can then put in a stimulus such as near-infrared light. The gold converts the light into heat, the heat causes the liposome to become leaky, and then whatever's really concentrated inside can diffuse out through the leaky liposome."
"Infrared light penetrates the deepest through the body because it interacts the least with most tissues, and it also prevents
|Contact: Daniel Stolte|
University of Arizona