One problem that confounds researchers who are developing nanoparticles for use as cancer imaging and therapeutic agents is that many nanoparticles accumulate blood proteins on their surfaces as they circulate through the body. This nonspecific absorption of proteins attracts attention from immune system cells, with the result that nanoparticles are often removed from circulation before reaching their tumor targets. And while nanoparticle developers have used various polymers such as poly(ethylene glycol) (PEG) to reduce nonspecific protein binding, the performance of these coated nanoparticles is still less than desired.
Reporting its work in the journal Biomacromolecules, a research team at the University of Washington in Seattle, headed by Shaoyi Jiang, Ph.D., has shown that a novel family of polymers may be able to replace PEG as a nanoparticle coating. These polymers, known as zwitterionic polymers, are covered with both positive and negative charges. These polymers pack together tightly when coated onto a surface, displaying their positive and negative charges at high density. As a result, the polymers are able to repel proteins from adhering to the surface, even when polymer-coated surfaces are treated with undiluted human serum or plasma. Thus, these zwitterionic polymers may prove useful as antifouling coating on nanoparticles.
This work is detailed in the paper “Zwitterionic polymers exhibiting high resistance to nonspecific protein adsorption from human serum and plasma.” An abstract of this paper is available at the journal’s Web site.