Credit: Georgina Such
Faced with an immune system that hunts and destroys molecules it doesn't recognise, drug carriers must find smart ways to access the right cells and deliver their cargo, says material scientist Georgina Such.
Outmanoeuvring biological defences is an ideal challenge for a materials scientist, says Such, part of a University of Melbourne team that is constructing 'intelligent' drug capsules.
Made up of layers of polymers, each with a different role, capsules are being engineered to travel undetected through the bloodstream and deliver their contents directly to cancer cells. In the process, they would avoid creating the side effects common to current chemotherapies, which occur when drugs affect healthy and diseased cells indiscriminately.
Work on drug delivery perfectly suits Such's interest in constructing unique materials to solve real-world problems. For her PhD work, Such collaborated with the Cooperative Research Centre for Polymers at the University of New South Wales in Sydney and national science agency CSIRO to help develop a new sunglass lens material that more quickly transitions from dark to light. Polymers in the material act like tiny cushions around colour-changing photochromic components, allowing them to more easily change structure and speeding up the colour change.
In choosing her next research topic, Such wanted to pursue an area with practical applications. "I was interested in something I could see made a real difference to a lot of people," she says.
Targeted Drug Delivery
At the University of Melbourne, Such and the 35-member research team are searching for ways to 'trick' the body through all stages of drug delivery, from the travelling through the bloodstream to entering cells to depositing therapeutic agents at specific targets.
The group recently developed a new drug capsule that uses cellular cues to release its cargo and degrade once inside a cell. After being engulfed by cells, capsules are confined in acidic compartments called endosomes. The altered conditions stimulate Such's capsule to swell and disrupt the crosslinking of the polymer, and this structural change releases the drug inside the cell.
Such and colleagues also constructed a capsule that can bind to an antibody found on colorectal cancer cells. Because these capsules target only diseased cells, they are much more specific than many other chemotherapies, which target more general landmarks like folates that are also found on healthy cells. Ninety-five percent of colorectal cancer cells have been shown to display this antibody, revealing the potential benefits of an antibody-targeting capsule in cancer treatments.
These polymer capsules are so useful, says Such, because their size and flexibility can be carefully controlled through a combination of techniques called layer-by-layer construction and click chemistry. Layers of polymer are deposited on top of one another, and they are bound together by strong chemical bonds that stabilise them in the body.
Her drug delivery work earned her a A$20,000 L'Oreal Women in Science fellowship, which will allow her to travel to present her work and fund more students in the Interfaces and Materials Group at the University of Melbourne. Such says she forsees a smart capsule like the one she is designing being commercially available within a few decades.
