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Honolulu, HI, United States, 2006/09/25 - Researchers are trying to trick the body's immune system, and increase the circulation time of nano drug carriers in the blood, with stealth drug nanoparticles that could be fabricated by self-assembling..
Phagocytosis is a cellular phenomena that describes the process in which phagocytes (specialized cells such as macrophages) destroy viruses and foreign particles in blood. Phagocytes are an important part of the immune system. Unfortunately, phagocytes are also a major limitation for the intravenous delivery of polymeric nanoparticles. The use of such nanoparticles to deliver therapeutic agents is currently being studied as a promising method by which drugs can be effectively targeted to specific cells in the body, such as cancerous cells. Researchers at Penn State are trying to trick the body's immune system, and increase the circulation time of nano drug carriers in the blood, with stealth drug nanoparticles that could be fabricated by self-assembling a shell on the surface of a solid drug core. This research could lead to the possibility of long term drug treatment in vivo.
Nanoparticles become recognizable to the cells of the mononuclear phagocyte system (MPS), and are subsequently cleared from circulation by phagocytosis, through a process called opsonization. An opsonin is a proteinaceous molecule that acts as a binding enhancer for the process of phagocytosis. Phagocytic cells express receptors that bind opsonin molecules.
In order to improve the in vivo survival rate of nanoparticles, researchers are therefore trying to engineer a long circulating nanocarrier with a surface that can avoid opsonin adsorption and the subsequent clearance from the body by phagocytic cells.
Dr. Michael V. Pishko, Professor of Chemical Engineering and Materials Science and Engineering at Penn State, explained the background of his group's research into nanoparticulate drug delivery to Nanowerk: "It has been established that the physicochemical characteristics of a polymeric nanoparticle such as surface charge, size, functional groups, and hydrophilicity can affect its uptake by the cells of the MPS. Previously, it was suggested that a long-circulating, "stealth" carrier could be designed by incorporating hydrophilic polymers on the surface of the polymeric carrier."
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By Michael Berger, Copyright 2006 Nanowerk LLC