A team of researchers from Rice University, Houston, TX, and The Methodist Hospital Research Institute say that submicroscopic particles containing even smaller particles of iron oxide could make magnetic resonance imaging (MRI) a far more powerful tool to detect and fight disease. They created composite particles that can be injected into patients, and then guided by magnetic fields. Once in position, the particles may be heated to kill malignant tissues or trigger the release of drugs at the site and then degrade and leave the body, they said.
Iron oxide particles can be manipulated with magnets, provide excellent contrast under MRI, create heat when triggered, and degrade quickly. But, the researchers explained, they can't do all that at once. Since many of these functions are size-dependent, the team found that the way to decouple the functions from their sizes was to package thousands of iron oxide particles (with magnetic cores as small as 5 nanometers across) inside larger particles.
The team embedded iron oxide particles inside silicon mesoporous particles (SiMPs) and discoidal polymeric nanoconstructs (DPNs). From previous research, they knew that submicron-sized SiMPs and DPNs naturally accumulate within the tumor's blood vessels.
Iron oxide enhances the ability to position and hold the particles in place with magnets. Their tests showed iron oxide particles made the nanoconstructs 10 times better than traditional contrast agents with what amounted to significantly lower doses of iron than used in current practice.
