Like bees and their honeycomb, a team of PNNL and University of Washington scientists have figured out a way to pack tumor killing antibodies into the cavities of porous silica particles, hopefully creating a superior transport system for anti-cancer agents.
They have demonstrated that they can embed antibodies into the structure of chemically modified silica particles that have already been shown to be biocompatible. “The silica’s mesoporous nature provides honeycomb-like structures that can pack lots of individual drug molecules,” says PNNL material scientist Jun Liu. “We’ve been exploring the material for our energy and environmental problems, but it seemed like a natural fit for drug delivery.”
The general idea is to spare noncancerous tissue from exposure to antibodies and direct an intense dose at the actual tumor site. According to results published in the Journal of the American Chemical Society, the particles can help anti-cancer antibodies prevent tumor growth and prolong the lives of mice.
The mesoporous silica particles have diameters of about six to 12 micrometers and pores of about 30 nanometers in diameter. The group was able to improve the containment of antibodies by attaching small chemical “barbs” of amine, carboxylic acid or sulfonic acid groups to the interior portion of the silica material’s pores. These barbs didn’t fully prevent the antibodies from leaking out, but the researchers discovered they could fine tune the leakage rate by tinkering with the the concentration and choice of chemical composition of the barbs.
In test on mice, the particles were injected directly into tumors. The results were significantly slowed tumor growth, compared with control groups, and prolonged life.
“We are very excited by our preliminary results,” says PNNL biochemist Chenghong Lei. “We plan to do some additional, larger studies with animals. We hope the results hold up well enough to take it to clinical trials somewhere down the road.”
The team is hopeful that the delivery system will prove effective with cancers that form solid tumors such as breast cancer.