Another advantage to protocells over lipsomes alone, says lead author Carlee Ashley, a Harry S. Truman post-doctoral fellow at Sandia's California site in Livermore, is that liposomes used as carriers need specialized loading strategies that make the process more difficult. "We've demonstrated we can just soak nanoparticles to load them with unique drug combinations needed for personalized medicine. They effectively encapsulate toxins as well as siRNA [ribonucleic acid] that silence expressions of proteins."
RNA, the biological messenger that tells cells which proteins to manufacture, in this case is used to silence the cellular factory, a way of causing apoptosis or cell death. "Si" is short for "silence."
The lipids also serve as a shield that restricts toxic chemotherapy drugs from leaking from the nanoparticle until the protocell binds to and takes hold within the cancer cell. This means that few poisons leak into the system of the human host, if the protocells find no cancer cells. This cloaking mitigates toxic side effects expected from conventional chemotherapy.
Instead, the particles crafted small enough to float under the radar of the liver and other cleansing organs can circulate harmlessly for days or weeks, depending on their engineered size, seeking their prey.
A library of phages viruses that attack bacteria was created at UNM's nationally accredited cancer center by collaborator David Peabody. This permitted researchers to expose the phages to a group of cancerous cells and normal cells, allowing identification of peptides that bind specifically to cancer cells but not normal cells.
"Proteins modified with a targeting peptide that binds to a particular carcinoma exhibit a 10,000-fold greater affinity for that cancer than for other unrelated cells," Ashley said.
Brinker adds, "A key feature of our protocell is that its fluid bilayer allows high-affinity bin
|Contact: Neal Singer|
DOE/Sandia National Laboratories