Scientists Use Near-Infrared Light and Injected DNA Nanodevice to Guide Stem Cells to a Wound – Accelerating the Healing Process


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Researchers can guide stem cells (like those in the illustration above) to an injury by using near-infrared light and an injected DNA nanodevice. (Image credit: Juan Gaertner/Shutterstock.com)

Imagine physicians having a remote control that they could employ to drive a patient’s own cells to a wound to accelerate the healing process.

Such a device is still away from reality, however, scientists have described in the ACS journal Nano Letters of having taken a key initial step: They employed near-infrared light and an injected DNA nanodevice to direct stem cells to a wound, which helped in the regrowth of muscle tissue in mice.

Complex signaling pathways synchronize cellular activities like proliferation, movement, and even death. For instance, when signaling molecules attach to proteins known as receptor tyrosine kinases on a cell’s surface, they stimulate the receptors to pair up and phosphorylate each other. This process can trigger other proteins that eventually result in a cell moving or growing.

Hong-Hui Wang, Zhou Nie, and partners doubted if they could set up a nanodevice to cells that would rewire this system, activating the receptors by near-infrared light rather than signaling molecules. The scientists opted for near-infrared as it can penetrate living tissues, in contrast to visible or ultraviolet light. The group aimed a receptor tyrosine kinase known as MET, which is important for wound healing.

The scientists developed a DNA molecule that can attach to two MET receptors at the same time, binding them together and stimulating them. In order to make the system responsive to light, the researchers linked multiple copies of the DNA sequence to gold nanorods. On irradiating near-infrared light, the nanorods get heated up and release the DNA so that it could trigger the receptors.

The scientists introduced the DNA-bound gold nanorods into mice at the injured area and illuminated a near-infrared light on the mice for a few minutes. After three days, more muscle stem cells had moved to the wound in treated mice when compared to those in untreated mice. The treated mice also exhibited improved signs of muscle regeneration in comparison to control mice.

The researchers acknowledge funding from the National Natural Science Foundation of China, National Science and Technology Major Project, the Young Top-Notch Talent for Ten Thousand Talent Program, the Keypoint Research and Invention Program of Hunan Province, and the National Institutes of Health.

 

 

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Dots, rods and tetrapods: CdSe gets in shape


Jan 31, 2011

QDOTS imagesCAKXSY1K 8Researchers from the South China University of Technology have presented a surfactant-free recipe for fabricating high-quality CdSe nanocrystals (NCs). The morphology, which includes irregular dots, rods, tetrapods and sphere-shapes, can be controlled easily by varying the experimental conditions. More importantly, the preparation techniques involved are simple, low-cost and can be used to fabricate other II-VI group semiconductor NCs.

CdSe Nanocrystals

CdSe nanocrystals: dots, nanorods and tetrapods

The CdSe NCs were produced with a fixed Cd/Se molar ratio of 2:1 and using 2.32 g of trioctylphosphine oxide (TOPO); at the same time, all the trioctylphosphine selenide (TOPSe) injections were kept at 1 ml, but with different concentrations. No other ligands were used in the case study.

Homogeneous CdSe NCs with different morphology were obtained under such experimental conditions. The sample quality (size distribution, optical properties, tetrapod selectivity) is as good as that of the best CdSe NCs synthesized by using extra ligands. As for the growth mechanism, we believed that the decomposition of TOPSe and cadmium myristate at a temperature of 240 or 300 °C would also supply in situ-generated TOP and myristic acid in the reaction mixture, which affected the anisotropic growth of CdSe NCs.

To further investigate the application of this surfactant-free recipe, the group is now optimizing the experimental conditions and has found that well controlled morphology of CdTe and/or CdSexTe1–x NCs can also be successfully fabricated.

Thanks to the easily controllable NC-growth kinetics, such a synthesis route is very promising for low cost, large-scale preparation of CdSe and CdTe NCs for application in solution-processed thin-film solar cells.

More information can be found in the journal Nanotechnology.

About the author

The study was funded by the National Natural Science Foundation of China (nos. 50703012, 50773023 and 50990065), the National Basic Research Program of China (973 program no. 2009CB623600) and SCUT grant (no. 2009ZZ0003). The experiments were performed at the Institute of Polymer Optoelectronic Materials and Devices, Key Laboratory of Special Functional Materials group. Hongmei Liu is a PhD student in materials science and holds a bachelors degree in chemistry. Currently she is exploring the fabrication of high-quality semiconductor nanostructures, together with the measurement and application of the resulting nanostructures in the field of solution processed thin-film solar cell systems and other nano-electronic devices.