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Posted: February 23, 2009
Nanoparticles detect dying cancer cells
(Nanowerk News) Two years ago, researchers at the University of South Australia discovered a new molecular marker specific for chemotherapy-induced cancer cell death. Now, those same investigators have used this marker to develop an imaging agent that can pinpoint tumor cell death using magnetic resonance imaging.
Reporting its work in the journal Advanced Materials (Immunotargeting of Functional Nanoparticles for MRI detection of Apoptotic Tumor Cells), a team of investigators led by Benjamin Thiery, Ph.D., first described a new synthetic method that produces monocrystalline iron oxide nanoparticles with a dense, uniform coating of the biocompatible polymer poly(ethylene glycol) (PEG). The resulting nanoparticle adsorbed much lower levels of blood proteins than do iron oxide nanoparticles coated using conventional methods, which had the effect of increasing the particles’ half-life in blood.
Next, the investigators attached a specific monoclonal antibody to the PEG coating. This antibody binds to the La ribonucleoprotein, a molecule that is highly overexpressed by tumor cells. When tumor cells die by a process known as apoptosis, La ribonucleoprotein migrates to the cell membrane, where it is then accessible to the monoclonal antibody. Using multiple experimental models, the investigators showed that this antibody-nanoparticle construct bound with very high specificity to apoptotic cancer cells. The investigators are now conducting in vivo experiments to determine whether the nanoparticles can reveal the presence of apoptotic cancer cells in animals with human tumors.