These images show UV-induced morphological changes of multinucleated giant cells, unprotected and protected by the group’s UV absorber. Credit: Shifeng Zhou/ South China University of Technology
A special metal oxide glass created by researchers in China can help protect living cells by absorbing and blocking damaging ultraviolet rays. It could be used in several applications, including as a protective shield for electronic instruments in space. The researchers used a metal oxide – cerium (IV) oxide (CeO2) – well-known for its ability to absorb UV photons to craft the composite glass-based UV absorber.
Other key features of the final composite material are optical transparency of the glass and ability to suppress the separation of photo-generated electrons and holes. The later feature slows down a light-induced reaction that would lead to the ultimate breakdown of the material under prolonged exposure to UV radiation. The method is based on the self-limited nanocrystallization of glass.
“Self-limited nanocrystallization of glass can be achieved by taking advantage of the rigid environment of the solid-state matrix, rather than the conventional solution and vapor conditions to modulate the ionic migration kinetics,” explained Shifeng Zhou. “It allows us to create glass-ceramics embedded with a CeO2:fluorine (F) nanostructure.” The viscous glass matrix involved poses a considerable constraint for oxide (O2-) and F- ion diffusion, so the group gradually etches trifluorocerium (CeF3) by O2- ions within an oxide matrix until F-doped CeO2 is generated in a controllable manner. It’s important to note that this technology is also routinely used to prepare other UV absorbers such as zinc oxide (ZnO) and titanium oxide (TiO2).
“This work establishes an effective approach for the functionalization of glass,” said Zhou. “And it allowed us to demonstrate the construction of a novel glass-based UV absorber.” The group’s innovative approach for fabricating the UV absorber has important implications “for the construction of novel glass materials with new functions via microstructure engineering,” he added. Among the group’s key discoveries was finding that the self-limited nanocrystallinization of glass is indeed an effective way to functionalize it. The special glass they created suppresses photocatalytic and catalytic activity, while boasting an extremely high UV-absorbing capacity.
“Our glass shows excellent optical quality, and it can be easily fabricated either in bulk form or as a film,” said Zhou. “It effectively protects organic dye and living cells from UV radiation damage.” Potential applications include radiation hardening of electronic devices, serving as a biological shield, and preserving cultural artifacts and relics. http://www.osa.org/en-us/about_osa/newsroom/news_releases/2016/glass-based_ultraviolet_absorbers_act_as_biologic/
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