Health and Medical News and Resources

General interest items edited by Janice Flahiff

[News release] Printing 3-D Graphene Structures for Tissue Engineering

From the 19 May 2015 McCormick Northwestern news release

People have tried to print graphene before,” Shah said. “But it’s been a mostly polymer composite with graphene making up less than 20 percent of the volume.”

With a volume so meager, those inks are unable to maintain many of graphene’s celebrated properties. But adding higher volumes of graphene flakes to the mix in these ink systems typically results in printed structures too brittle and fragile to manipulate. Shah’s ink is the best of both worlds. At 60-70 percent graphene, it preserves the material’s unique properties, including its electrical conductivity. And it’s flexible and robust enough to print robust macroscopic structures. The ink’s secret lies in its formulation: the graphene flakes are mixed with a biocompatible elastomer and quickly evaporating solvents.

“It’s a liquid ink,” Shah explained. “After the ink is extruded, one of the solvents in the system evaporates right away, causing the structure to solidify nearly instantly. The presence of the other solvents and the interaction with the specific polymer binder chosen also has a significant contribution to its resulting flexibility and properties. Because it holds its shape, we are able to build larger, well-defined objects.”

Supported by a Google Gift and a McCormick Research Catalyst Award, the research is described in the paper “Three-dimensional printing of high-content graphene scaffolds for electronic and biomedical applications,” published in the April 2015 issue of ACS Nano. Jakus is the paper’s first author. Mark Hersam, the Bette and Neison Harris Chair in Teaching Excellence, professor of materials science and engineering at McCormick, served as coauthor.

The 3-D printed graphene scaffold appeared on the cover of ACS Nano.

The 3-D printed graphene scaffold appeared on the cover of ACS Nano.

An expert in biomaterials, Shah said 3-D printed graphene scaffolds could play a role in tissue engineering and regenerative medicine as well as in electronic devices. Her team populated one of the scaffolds with stem cells to surprising results. Not only did the cells survive, they divided, proliferated, and morphed into neuron-like cells.

“That’s without any additional growth factors or signaling that people usually have to use to induce differentiation into neuron-like cells,” Shah said. “If we could just use a material without needing to incorporate other more expensive or complex agents, that would be ideal.”

The printed graphene structure is also flexible and strong enough to be easily sutured to existing tissues, so it could be used for biodegradable sensors and medical implants. Shah said the biocompatible elastomer and graphene’s electrical conductivity most likely contributed to the scaffold’s biological success.

“Cells conduct electricity inherently — especially neurons,” Shah said. “So if they’re on a substrate that can help conduct that signal, they’re able to communicate over wider distances.”

 

May 22, 2015 Posted by | Medical and Health Research News | , , , , | Leave a comment

How cranberries impact infection-causing bacteria

From the 15 July 2013 article at EurkeAlert

How cranberries impact infection-causing bacteria

Research points to potential role for cranberry derivatives in implantable medical devices

 IMAGE: Professor Nathalie Tufenkji is in her McGill University lab.

Click here for more information. 

Consuming cranberry products has been anecdotally associated with prevention of urinary tract infections (UTIs) for over 100 years. But is this popular belief a myth, or scientific fact?

In recent years, some studies have suggested that cranberries prevent UTIs by hindering bacteria from sticking to the walls of the urinary tract, thanks to phytochemicals known as proanthocyanidins (PACs). Yet the mechanisms by which cranberry materials may alter bacterial behaviour have not been fully understood.

Now, researchers in McGill University’s Department of Chemical Engineering are shedding light on the biological mechanisms by which cranberries may impart protective properties against urinary tract and other infections. Two new studies, spearheaded by Prof. Nathalie Tufenkji, add to evidence of cranberries’ effects on UTI-causing bacteria. The findings also point to the potential for cranberry derivatives to be used to prevent bacterial colonization in medical devices such as catheters.

In research results published online last month in the Canadian Journal of Microbiology, Prof. Tufenkji and members of her laboratory report that cranberry powder can inhibit the ability of Proteus mirabilis, a bacterium frequently implicated in complicated UTIs, to swarm on agar plates and swim within the agar. The experiments also show that increasing concentrations of cranberry powder reduce the bacteria’s production of urease, an enzyme that contributes to the virulence of infections.

These results build on previous work by the McGill lab, showing that cranberry materials hinder movement of other bacteria involved in UTIs. A genome-wide analysis of an uropathogenic E. colirevealed that expression of the gene that encodes for the bacteria’s flagellar filament was decreased in the presence of cranberry PACs.

The team’s findings are significant because bacterial movement is a key mechanism for the spread of infection, as infectious bacteria literally swim to disseminate in the urinary tract and to escape the host immune response.

“While the effects of cranberry in living organisms remain subject to further study, our findings highlight the role that cranberry consumption might play in the prevention of chronic infections,” Tufenkji says. “More than 150 million cases of UTI are reported globally each year, and antibiotic treatment remains the standard approach for managing these infections. The current rise of bacterial resistance to antibiotics underscores the importance of developing another approach.”

Another recent study led by Tufenkji in collaboration with McGill professor Showan Nazhat, a biomaterials expert at the Department of Mining and Materials Engineering, finds that cranberry-enriched silicone substrates impaired the spread of Proteus mirabilis. Those results, published online in the journal Colloids and Surfaces B: Biointerfaces, point to potential use for cranberry derivatives to hinder the spread of germs in implantable medical devices such as catheters, which are frequently implicated in UTIs.

“Based on the demonstrated bioactivity of cranberry, its use in catheters and other medical devices could someday yield considerable benefits to patient health,” Tufenkji says.

 

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Funding for the new studies was provided by the Natural Sciences and Engineering Research Council of Canada, the Canada Research Chairs program, the Wisconsin Cranberry Board, the Cranberry Institute, the Fonds québécois de la recherche sur la nature et les technologies, and the Fonds de la recherche en santé du Québec.

Link to the Canadian Journal of Microbiology article: http://www.nrcresearchpress.com/doi/abs/10.1139/cjm-2012-0744#.UctRHjvqlLc

Link to the Colloids and Surfaces B: Biointerfaces article: http://www.sciencedirect.com/science/article/pii/S0927776513002348

 

 

July 19, 2013 Posted by | Medical and Health Research News | , , , , , , , | Leave a comment

   

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