Gold has been used in medicine for centuries, but nanotechnology has given it an entirely new role. Researchers led by Younan Xia at Washington University in St. Louis have developed hollow gold nanostructures — called nanocages — that could simultaneously image tumors and deliver drugs to destroy them, all in a single platform.
The nanocages are extraordinarily small, about 50 nanometers in size, and their hollow interiors can be loaded with drug molecules. Their gold walls can be engineered to absorb near-infrared (NIR) light — wavelengths that pass through tissue relatively easily. When NIR light hits the nanocages, two things happen: they emit Cerenkov radiation that can be detected in imaging, and they convert the light to heat, which can kill nearby tumor cells through photothermal therapy.
The Cerenkov Imaging Advantage
Cerenkov luminescence imaging is a relatively new technique that detects visible light emitted when charged particles (like those from radioactive tracers) travel through tissue faster than light does in that medium. By incorporating gold-198 — a radioactive isotope — directly into the walls of the nanocages, the team created particles that are self-labeling. The gold-198 provides both the imaging signal and becomes a permanent, structural part of the nanocage. Because the isotope is built into the cage wall rather than chemically attached, there's no risk of it separating from the nanoparticle during treatment — a common concern with conventional nanoparticle labeling approaches.
Drug Delivery and Combination Therapy
The hollow interior of the nanocages can be filled with chemotherapy drugs or other therapeutic agents. By attaching targeting molecules like peptides to the outer surface, the team hopes to direct the nanocages specifically to tumor cells, minimizing harm to healthy tissue. Once at the tumor site, the nanocages could deliver drugs, apply photothermal heat, or both simultaneously.
This kind of multifunctional nanoparticle — one that can image, target, and treat — represents the direction that cancer nanomedicine is heading. Combining diagnosis and therapy in a single agent, sometimes called theranostics, could make cancer treatment more precise and more efficient than approaches that handle imaging and treatment as separate steps.
Source: Physics World
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