Oct 31, 2013
Zinc oxide tracks cells
Zinc oxide (ZnO) is a simple metal oxide that is used in many consumer products. Its unique optical and electronic properties mean that it might be used in many new application areas, including blue luminescent devices, ultraviolet detectors, solar cells, photocatalysts, and ultraviolet protective additives. A team led by Dai Soo Lee at the Chonbuk National University in Korea and Shan-hui Hsu of the National Taiwan University in Taiwan has now succeeded in synthesizing ZnO nanoparticles (NPs) around 2 nm in size in methanol. These materials could be used as antibacterial and antifungal additives in polyurethane and epoxy coatings.
The Taiwan and Korea team has also found that ZnO NPs quantum dots (QDs) show promise for biological labelling and the researchers have been looking at how the materials may be used to label stem cells. They have found that the ZnO QDs are antibacterial, have low cytotoxicity and can be used as efficient labels on a variety of cells, including stem cells.
In this work, researchers in Prof. Lee’s labs began by synthesizing green fluorescent ZnO QDs that were around 2 nm in size on average, in methanol. Prof. Hsu’s team then further modified the ZnO QDs using polyethylene glycol (PEG) to form water-dispersible ZnO QDs. Fourier transform infrared spectroscopy (FTIR) spectra on the materials revealed that PEG molecules were attached to the ZnO QDs and no obvious size alteration was observed for ZnO QDs after PEG conjugation as seen by high-resolution TEM. The water-dispersible ZnO QDs remained antibacterial and fluorescent. They also remained biocompatible.
Cytotoxicity evaluations showed that the ZnO QDs were generally safe in concentrations of 30 ppm or below and ZnO QD-labelled adipose-derived adult stem cells (ADAS) maintained their ability to differentiate (differentiation is a hallmark of stem cells). Moreover, the reduced oxygen consumption upon exposure to a low amount of ZnO QDs may even facilitate their differentiation by metabolic compensation through glycolysis.
The team now plans to study the materials in more detail and fully explore their potential in biological labelling and other applications.
More information can be found in the journal Nanotechnology (in press).
About the author
Prof. Shan-hui Hsu has been an active researcher in the field of biomaterials since 1992. She is now a distinguished professor at National Taiwan University. Prof. Dai Soo Lee has been an active researcher in the field of functional polymers with nanoparticles at Chonbuk National University in Republic of Korea since 1989. He was R&D manager at Hannam Chemical before he joined Chonbuk National University.