A new twist on nanoparticle behavior

Researchers hoping to develop linkurl:nanoparticles;http://www.the-scientist.com/article/display/15659/ as medicines or carriers of therapeutic molecules have much more to worry about than the type of material they plan on miniaturizing, according to a linkurl:study;http://www.pnas.org/cgi/doi/10.1073/pnas.0805135105 in this week's issue of the __Proceedings of the National Academy of Science__. Researchers in Ireland found that the corona, or cloud of proteins and other biomolecules that adher

By | September 23, 2008

Researchers hoping to develop linkurl:nanoparticles;http://www.the-scientist.com/article/display/15659/ as medicines or carriers of therapeutic molecules have much more to worry about than the type of material they plan on miniaturizing, according to a linkurl:study;http://www.pnas.org/cgi/doi/10.1073/pnas.0805135105 in this week's issue of the __Proceedings of the National Academy of Science__. Researchers in Ireland found that the corona, or cloud of proteins and other biomolecules that adheres to a nanoparticle immersed in biological media (in this study human blood plasma), changes depending on the size of the nanoparticle and the charge on its surface. That, in turn, can affect the particles' therapeutic action in the body. Nanotechnology is "an enormously powerful tool, but we need to know how to control it," linkurl:Kenneth Dawson,;http://www.ucd.ie/chem/dawson/index.html a University College Dublin physical chemist and the study's senior author, told __The Scientist__. "We have to look at what's happening at the surface of these materials rather than just the materials themselves. It's a new science really." According to Dawson, the study represents a "paradigm shift" in how chemists typically think about the interaction of nanoparticles in biological settings. Traditionally the composition of the nanoparticle itself was thought to be the most important safety and functionality consideration. With Dawson's paper, the importance of the corona, and the physical factors which shape it, comes to the fore. "The biological identity of a particle depends not only on its own material, but also what it picks up in the surroundings," Dawson said. Dawson and his group last year linkurl:coined;http://www3.interscience.wiley.com/journal/114282746/abstract the term "corona" for the conglomeration of proteins adhering to nanoparticles in biological media. Since then, the group has been exploring the properties of coronas. In the present study, the researchers found that nanoparticles introduced, in vitro, to human plasma accumulated markedly different coronas depending on their size and charge. For example, his team found that uncharged particles attracted more immunoglobulins while charged particles pulled in more fat-shuttling proteins. "They pulled on quite different proteins," Dawson explained. This, Dawson said, could have major implications for nanoparticles used as human therapeutics. For example, a particle of one size and surface charge might be trafficked to the brain of a patient, while another particle of a different size and charge, even though it's made of the same material, might be shuttled to the liver. "[A nanoparticle] can go places you didn't want it to go, and when it gets there it might pick up different signals that can be confusing," he said. Drug makers and regulators should consider the effects of nanoparticle size and surface when developing and monitoring therapies that use nanotechnology, he added. University of Rochester professor of environmental medicine and toxicology linkurl:Gunter Oberdorster,;http://www2.envmed.rochester.edu/envmed/TOX/faculty/oberdoerster.html who was not involved in the study, noted that drug makers may be able to make use of the differing physiological effects different coronas have on a nanoparticle's fate in the body. "Nanomedicine may take advantage of this and target a specific organ." While he called Dawson's study "an important step," he cautioned that in vivo studies must confirm the effects of nanoparticle size and surface character in living organisms. According to Dawson, other researchers are conducting preliminary in vivo studies in mice to explore how nanoparticle sizes and surface properties affect the physiological activity of the tiny particles in living systems. Although no treatments or therapeutics that use nanoparticles are currently on the market, experimental cancer treatments and other nanotechnology-based therapies are nearing FDA approval, according to Rice University chemist and Director of the International Council on Nanotechnology, linkurl:Kristen Kulinowski.;http://cohesion.rice.edu/naturalsciences/chemistry/FacultyDetail.cfm?RiceID=1200 "This [study] bolsters the argument about the vital need for good, quality characterization [of nanomedicines], the actual species the body will experience," she told The __Scientist__.

Comments

Avatar of: anonymous poster

anonymous poster

Posts: 34

September 23, 2008

The differences are minimal, so is that a big deal in terms of biological effects? You can argue for it, but I don't think so.
Avatar of: Paul Stein

Paul Stein

Posts: 23

September 23, 2008

Biological scientists have known for many decades that specific molecules are shuttled around in the circulation by specific proteins to specific sites.\n\nWhy the surprise here?
Avatar of: PETER DEHAAN

PETER DEHAAN

Posts: 1

September 24, 2008

Why not simply focus on nanoparticles that co-evolved with humans and highly efficiently deliver their content to specific target cells. Such ideal nanoparticles already exist and we call them viral vector particles.
Avatar of: Jp Moya

Jp Moya

Posts: 1

September 25, 2008

As was mentioned earlier, I don't understand how this is a recent discovery. Don't all biologists known that as soon as you insert a foreign material into an our body you get proteins (fibronectine I beleive ?) that adhere to and coat the material.\n\n

September 22, 2009

First, viral vector particles do not have thermal, electrical or magnetic properties that can be used to enhance the effectiveness of the therapeutic that is being delivered. Secondarily, I would consider one explaining the fact that various proteins travel to different parts of the body as overstating the obvious. Certain proteins will only adhere to a particular surface charge and if the size of the nanostructure-protein complex does not pass junctional complexes, the nanoparticles will be rendered immobile. In defense of the author, he is saying that the sizes and surface charges on nanoparticles can be fine-tuned, perhaps so that specific proteins may aggregate to the surface of these tiny bionanomaterials allowing them to target particular regions of interest within the body. This is novel because until recently, researchers have been relying solely upon the intrinsic properties of the nanoparticle materials, which by the way, can behave quite differently from the same material in a bulk size.

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