Lights, Carbon Nitride, Bone Regeneration!

Growing stem cells on carbon nitride sheets not only activates bone-related genes, but also releases calcium ions when exposed to red light.

AsianScientist (Feb. 15, 2017) – Light absorbing nanosheets could help bone regrowth, according to a study by researchers at the Ulsan National Institute of Science and Technology published in ACS Nano.

Human bone marrow-derived mesenchymal stem cells (hBMSCs) have been successfully used to treat fractures by regenerating lost bone tissue. To increase the area of bone regeneration, scientists have attempted to enhance the function of stem cells using carbon nanotubes, graphenes and nano-oxides.

In the present study, Professors Kim Kwang S. and Suh Pann-Ghill examined the bone regenerative abilities of carbon nitride (C3N4) nanosheets. Firstly, Kim’s team synthesized carbon nitrogen derivatives from melamine compounds. Then, they analyzed the light-absorbing characteristics of C3N4 sheets at a wavelength range of 455-635 nanometers (nm).

They found that the C3N4 sheets emit fluorescence at the wavelength of 635 nm when exposed to red light in a liquid state. The released electrons induced calcium to accumulate in the cytoplasm, thereby speeding up bone regeneration.

Suh’s team then conducted studies investigating biomedical applications of this material. To do so, they cultured stem cells and cancer cells in a medium containing 200 μg/ml of C3N4 sheets. The material showed no cytotoxicity after two days of testing, suggesting that it is biocompatible.

They also confirmed that C3N4 sheets induce stem cells to differentiate into osteoblasts to promote mineral formation, turning on osteogenic differentiation marker genes such as ALP, BSP, and OCN. Moreover, Runx2 (Runt-related transcription factor 2), a key transcription factor in osteoblast differentiation was also activated. This gene activation resulted in the increased osteoblast differentiation and accelerated bone formation.

“This research has opened up the possibility of developing a new medicine that effectively treats skeletal injuries, such as fractures and osteoporosis,” said co-author Professor Seo Young-Kyo. “It will be a very useful tool for making artificial joints and teeth with the use of 3D printing.”

“This is an important milestone in the analysis of biomechanical functions needed for the development of biomaterials, including adjuvants for hard tissues such as damaged bones and teeth.”

The research team expects that their findings affirm the potential of C3N4 sheets in developing bone formation and directing hBMSCs toward bone regeneration.

The article can be found at: Tiwari et al. (2016) Accelerated Bone Regeneration by Two-Photon Photoactivated Carbon Nitride Nanosheets.


Source: Ulsan National Institute of Science and Technology.
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