Gallium nitride materials can be too rough for cells

Researchers at North Carolina State University have determined that the surface texture of gallium nitride (GaN) materials can influence the health of nearby cells. This work is significant because such GaN materials are of interest for developing new devices that can control cellular behavior.

GaN materials have a unique suite of properties that make them viable candidates for bioelectronic devices: they are nontoxic; they don't easily degrade in aqueous environments like the body; and the charge on their surface can be tuned.

"But while living cells will survive in the presence of GaN, we wanted to know if we could influence the behavior of the cells by changing the make-up of the GaN material," says Patrick Snyder, a PhD student at NC State and lead author of a paper on this work in RSC Advances. "Basically, we wanted to know if engineering the GaN could influence the health and metabolism of the surrounding cells."

To find out, the researchers tested three different GaN materials: straight GaN, and two varieties of aluminum gallium nitride – Al_0.8Ga0_.2N and Al_0.7Ga_0.3N. The researchers manipulated the surface of these materials, creating rough and smooth versions of each. Lastly, the researchers modified the surface chemistry of the materials to make them hydrophilic or hydrophobic.

"This tells us that the topography of the material matters, and can influence cellular behavior."Albena Ivanisevic, North Carolina State University

This produced six types of each material. For straight GaN, for example, the six types were: hydrophobic, hydrophilic and unmodified rough GaN; and hydrophobic, hydrophilic and unmodified smooth GaN. The same was also true for both varieties of AlGaN.

The researchers then used these materials as substrates for growing PC12 cells – a line of well-studied model cells. During the seven-day experiment, the researchers monitored the cell cultures to track the health and metabolism of the cells.

"We found that the roughly-textured AlGaN compositions released more gallium into the cellular environment," Snyder says. "While this did not kill the cells, it did cause metabolic changes."

"This tells us that the topography of the material matters, and can influence cellular behavior," says Albena Ivanisevic, a professor of materials science and engineering at NC State and co-author of the paper. "The work demonstrates that surface textures of bulk materials – like those used to create devices – can have similar effects to what we've previously seen in nanoscale materials."

This story is adapted from material from North Carolina State University, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.