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A Magnetic Attraction to Nanoparticles

March 9, 2012


By Jason Jacks

Barney Bishop

It’s not easy separating out a particle that is one-billionth the length of a meter from complex solutions and suspensions. But Mason biochemist Barney Bishop and his team of researchers aim to do just that with a tool most people are already familiar with—a magnet.

This strategy could simplify the collection of proteins while avoiding the use of a centrifuge, the method currently employed to recover particles used in biomarker discovery, Bishop points out.

Bishop is an expert in small—very small. A researcher in the Department of Chemistry and Biochemistry, Bishop can often be found poring over images and data about molecules in hopes of advancing the battle against certain diseases.

Bishop’s research interests lie predominantly in bio-inspired nanotechnologies and their applications. Generally, scientists in this area study, develop, and work with particles and nanomaterials that fall somewhere between 1 and 100 nanometers in size. (For reference, a sheet of paper is about 100,000 nanometers thick.) Many of the particles Bishop and his team work with fall outside this range, but at a size of somewhere between 400 and 1,100 nanometers in diameter, they are considerably small nonetheless.

With training in peptide chemistry and protein engineering, Bishop is interested mainly in applying peptide and protein engineering principles to investigate the workings of biomolecules in hopes of improving treatments for infections brought on by bacteria, many of which have become resistant to drug treatment.

Bishop’s work in nanotechnology began with the study of tiny acrylic acid hydrogel particles to see how their structural and chemical properties and structures could be altered. This study was part of a collaboration with the Center for Applied Proteomics and Molecular Medicine at Mason to develop hydrogel particles to facilitate the discovery of cancer biomarkers.

“At this point, we are laying the groundwork for where we want to go with this,” he says of nanotechnology, acknowledging much of his work in this field is still in its infancy.

Regarding his team’s research into magnetizing nanoparticles, the idea arose out of necessity. Currently, when attempting to isolate low-molecular-weight peptides, proteins, and other biomolecules, Bishop, like other researchers, uses a centrifuge to separate out the nanoparticles from a solution. This technique is time consuming because centrifuging is a multistep process that can also add stress to the nanoparticles being studied. “It would be easier if you didn’t have to centrifuge everything,” says Bishop.

In an attempt to remove centrifuging from the process, Bishop and his team looked to magnets as a viable alternative. As a first step, they incorporated iron oxide nanoparticles within acrylamide-based hydrogel particles, magnetizing them and giving them the ability to be recovered through the application of an external magnetic field.

With the apparent success achieved in their initial efforts (the results were published in the journal Polymers in July 2011), Bishop says the next step is to follow up that study by applying what they have learned so far from the magnetic acrylamide particles in the design of magnetized particles better suited for peptide and protein harvesting. “We just need to work out some kinks” before moving ahead with these studies, he says.

According to Bishop, one of the challenges in working with nanosize particles is their unpredictability because nanoparticles tend not to act like their larger counterparts. “Compounds that behave one way under normal circumstances can behave completely different in the nanoscale,” he says. “They can be more reactive or less reactive at the nanoscale. That is why there is so much interest in this.”

Another challenge of nanoscale is viewing what you are working with. To rectify this, Bishop and others in his lab employ a variety of technologies and techniques to analyze nanoparticles.

For instance, they use a technique called dynamic light scattering to determine the size of particles suspended in a solution. The result is a set of data Bishop and his team can analyze, although no picture of the particles is created. To get an image of what he is working with, Bishop employs atomic force microscopy, which creates a topographical map of the particles, providing information about their size and shape.

And while magnetizing nanoparticles may be part of Bishop’s most recent work in nanotechnology, it doesn’t stop there. His team is also employing nanotechnology to advance research into protein and peptide harvesting and the identification of “interesting molecules,” as Bishop puts it. The team is also looking to improve the use of nanoscale molecules as biological sensors, detectors, and reporters, which play important roles in the early detection of certain diseases such as cancer.

Bishop is again quick to point out that much of his team’s work is still in the early stages, but their research into nanoparticles, he points out, is building a framework for potentially bigger things to come.

“[It is hoped that nanotechnology] will allow us to discover new proteins, new peptides, and new molecules for potential therapeutic applications,” says Bishop. “That’s where we are hoping to take these particles in the grand scheme of things.”


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