11-10 :: October 2011

nanotimes News in Brief

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Gallium Nitride (GaN) // Research Finds Gallium Nitride is Non-Toxic, Biocompatible © Text: Purdue University / NCSU, U.S.

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esearchers from North Carolina State University and Purdue University have shown that the

semiconductor material gallium nitride (GaN) is non- toxic and is compatible with human cells – opening the door to the material’s use in a variety of biome- dical implant technologies. GaN is currently used in a host of technologies, from LED lighting to optic sensors, but it is not in widespread use in biomedi- cal implants. However, the new findings mean that GaN holds promise for an array of implantable technologies – from electrodes used in neurostimu- lation therapies for Alzheimer’s to transistors used to monitor blood chemistry.

“The first finding is that GaN, unlike other semi- conductor materials that have been considered for biomedical implants, is not toxic. That minimizes risk to both the environment and to patients,” says Dr. Albena Ivanisevic, who co-authored a paper descri- bing the research.

Researchers used a mass spectrometry technique to see how much gallium is released from GaN when the material is exposed to various environments that mimic conditions in the human body. This is impor- tant because gallium oxides are toxic. But the resear- chers found that GaN is very stable in these environ- ments – releasing such a tiny amount of gallium that it is non-toxic.

The researchers also wanted to determine GaN’s potential biocompatibility.

To do this they bon- ded peptides – the building blocks that make up proteins – to the GaN material. Researchers then placed peptide-coated GaN and uncoated GaN into cell cultures to see how the material and the cells interacted.

Researchers found that the peptide-coated GaN bon- ded more effectively with the cells. Specifically, more cells bonded to the material and those cells spread over a larger area.

Image: SEM image of cell growth on GaN that has been coated with peptides. © NCSU / Purdue University

Scott A. Jewetta, Matthew S. Makowskia, Benjamin An- drewsc, Michael J. Manfrad, Albena Ivanisevic: Gallium nitride is biocompatible and non-toxic before and after functionalization with peptides, In: Acta Biomaterialia (in print), DOI:10.1016/j.actbio.2011.09.038 http://dx.doi.org/10.1016/j.actbio.2011.09.038