January 30, 2006
Polymer-Coated Anticancer Drug Nanocrystals
Using a layer-by-layer process for growing polymer capsules, researchers at the University of Michigan in Ann Arbor have developed a process for entrapping nanocrystals of poorly soluble drugs in multilayered drug delivery devices. The layer-by-layer technology allows for careful tailoring of the capsule’s specific chemical and physical properties to match those needed for optimal drug delivery characteristics.
James Baker Jr., M.D., and his colleagues used a layer-by-layer approach to create dextran nanocapsules containing the potential anticancer agent 2-methoxyestradiol (2-ME), a molecule that is insoluble in water and thus difficult to deliver to tumors. 2-ME is also rapidly metabolized by the body to a form that has little anticancer activity.
Reporting their work in the journal, Molecular Pharmaceutics, the investigators began by taking nanocrystals of the drug and coating them with a charged fatty molecule – the fatty portion of this coating adhered to the drug nanocrystal surface, while the charged portion provided a surface upon which to deposit layers of dextran polymer. Tests with cultured thyroid cancer cells showed that encapsulated drug crystals retained all of the anticancer activity of the native drug.
The investigators are now conducting tests with this formulation in tumor-bearing mice. They also note that studies are underway with different polymer coatings in order to measure the effect that capsule surface charge and other chemical properties have on drug delivery parameters such as tumor targeting and biodistribution.
This work, funded by the National Cancer Institute, is detailed in a paper titled, “Encapsulation of submicrometer-sized 2-methoxyestradiol crystals into polymer multilayer capsules for biological applications.” This paper was published online in advance of print publication. An abstract is available at the journal’s website.