To facilitate precise drug delivery, scientists have developed a novel method to enable miniature drug-filled nanocarriers to dock on to immune cells, which in turn attack tumors. The team believes this development could lead to targeted treatment that could eliminate damage to healthy tissue.
These nanocarriers, described in a recent Nature Nanotechnology paper, are analogous to miniature submarines but no larger than a thousandth of the diameter of a human hair. Invisible to the naked eye, these nanocarriers are loaded with a pharmacologically active agent, allowing them to function as concentrated transport containers. The surface of these drug capsules is specially coated to enable them, for example, to dock on to tissue interspersed with tumor cells. The coating is usually composed of antibodies that act much like address labels to seek out binding sites on the target cells, such as tumor cells or immune cells that attack tumors.
Professor Volker Mailänder and his team from the University Medical Center of Johannes Gutenberg University Mainz recently developed the method of binding antibodies to such drug capsules. "Up to now, we have always had to use elaborate chemical methods to bind these antibodies to nanocapsules," he explained. "We have now been able to show that all that you need to do is to combine antibodies and nanocapsules together in an acidified solution."
In their paper, the researchers report that binding nanocapsules and antibodies in this way is almost twice as efficient as chemical bonding in the test tube, significantly improving the targeted transport of drugs. In conditions such as those found in the blood, they also found that chemically coupled antibodies almost completely lost their efficacy, while antibodies that are not chemically attached remained functional.
"The standard method of binding antibodies using complex chemical processes can degrade antibodies or even destroy them, or the nanocarrier in the blood can become rapidly covered with proteins," explained Professor Katharina Landfester from Max Planck Institute for Polymer Research. In contrast, the new method, which is based on the physical effect known as adsorption or adhesion, protects the antibodies. This makes the nanocarrier more stable and enables it to distribute the drugs more effectively in the body.
A video showing how the nanocarriers function is available for viewing.
Image: Combining a tiny drug capsule, a nanocarrier, with antibodies under acidic conditions results in the antibodies attaching to the drug carrier in a stable way. This makes it possible for nanocarriers to target diseased tissue. Image courtesy of Stefan Schuhmacher.