Nanometre-sized 'cargo ships' that can sail throughout the body via the bloodstream, and ferry anti-cancer drugs into tumours that might otherwise go untreated or undetected have been created by US scientists.
Ji-Ho Park, a graduate student at the University of California, San Diego, says that these ships can even avoid rapid removal by the body's natural immune system.
The researcher has revealed that the whole system is composed of a magnetic nanoparticle, a fluorescent quantum dot, and an anti-cancer drug molecule that will be left on the site of the tumour.
"The idea involves encapsulating imaging agents and drugs into a protective 'mother ship' that evades the natural processes that normally would remove these payloads if they were unprotected," said Michael Sailor, a professor of chemistry and biochemistry at UCSD who headed the team of chemists, biologists and engineers that turned the fanciful concept into reality.
"These mother ships are only 50 nanometres in diameter, or 1,000 times smaller than the diameter of a human hair, and are equipped with an array of molecules on their surfaces that enable them to find and penetrate tumour cells in the body," the researcher added.
Published in the Germany-based chemistry journal Angewandte Chemie, the research paper suggests that these microscopic cargo ships may one day provide the means to more effectively deliver toxic anti-cancer drugs to tumours in high concentrations without negatively impacting other parts of the body.
"Many drugs look promising in the laboratory, but fail in humans because they do not reach the diseased tissue in time or at concentrations high enough to be effective," said Sangeeta Bhatia, a physician, bioengineer and professor of Health Sciences and Technology at MIT who played a key role in the development.
"These drugs don't have the capability to avoid the body's natural defences or to discriminate their intended targets from healthy tissues. In addition, we lack the tools to detect diseases such as cancer at the earliest stages of development, when therapies can be most effective," she added.
The researchers have revealed that they designed the hull of the ships to evade detection by constructing them of specially modified lipids, a primary component of the surface of natural cells.
The lipids were modified in such a way as to enable them to circulate in the bloodstream for many hours before being eliminated, and the research group showed this in a series of experiments with mice.
The researchers also claim that the material of the hull is strong enough to prevent accidental release of its cargo while circulating through the bloodstream.
A phial of anti-cancer nano-ships glows red under a black light because the particles contain fluorescent "quantum dot" nanoparticles.
"We are now constructing the next generation of smart tumour-targeting nanodevices. We hope that these devices will improve the diagnostic imaging of cancer and allow pinpoint targeting of treatments into cancerous tumours," said Erkki Ruoslahti, a cell biologist and professor at the Burnham Institute for Medical Research at UC Santa Barbara.
"This study provides the first example of a single nanomaterial used for simultaneous drug delivery and multimode imaging of diseased tissue in a live animal," said Ji-Ho Park.
The researchers are now working on developing ways to chemically treat the exteriors of the nano-ships with specific chemical "zip codes" that will allow them to be delivered to specific tumours, organs and other sites in the body.