Tag Archives: Yi-Chung Wang

Glucose-sensing contact lens invented by US and Korean researchers

Blood tests for glucose levels may one day be a feature of the past according to an Oct. 3, 2016 news item on ScienceDaily,

Blood testing is the standard option for checking glucose levels, but a new technology could allow non-invasive testing via a contact lens that samples glucose levels in tears.

“There’s no noninvasive method to do this,” said Wei-Chuan Shih, a researcher with the University of Houston [UH] who worked with colleagues at UH and in Korea to develop the project, described in the high-impact journal Advanced Materials. “It always requires a blood draw. This is unfortunately the state of the art.”

A Sept. 27, 2016 UH news release (also on EurekAlert) by Jeannie Kever, which originated the news item, describes the proposed technology,

… glucose is a good target for optical sensing, and especially for what is known as surface-enhanced Raman scattering spectroscopy [also known as surface-enhanced Raman scattering or surface-enhanced Raman spectroscopy, and SERS], said Shih, an associate professor of electrical and computer engineering whose lab, the NanoBioPhotonics Group, works on optical biosensing enabled by nanoplasmonics.

This is an alternative approach, in contrast to a Raman spectroscopy-based noninvasive glucose sensor Shih developed as a Ph.D. student at the Massachusetts Institute of Technology. He holds two patents for technologies related to directly probing skin tissue using laser light to extract information about glucose concentrations.

The paper describes the development of a tiny device, built from multiple layers of gold nanowires stacked on top of a gold film and produced using solvent-assisted nanotransfer printing, which optimized the use of surface-enhanced Raman scattering to take advantage of the technique’s ability to detect small molecular samples.

Surface-enhanced Raman scattering – named for Indian physicist C.V. Raman [Raman scattering; SERS history begins in 1973 according to its Wikipedia entry], who discovered the effect in 1928 – uses information about how light interacts with a material to determine properties of the molecules that make up the material.

The device enhances the sensing properties of the technique by creating “hot spots,” or narrow gaps within the nanostructure which intensified the Raman signal, the researchers said.

Researchers created the glucose sensing contact lens to demonstrate the versatility of the technology. The contact lens concept isn’t unheard of – Google has submitted a patent for a multi-sensor contact lens, which the company says can also detect glucose levels in tears – but the researchers say this technology would also have a number of other applications.

“It should be noted that glucose is present not only in the blood but also in tears, and thus accurate monitoring of the glucose level in human tears by employing a contact-lens-type sensor can be an alternative approach for noninvasive glucose monitoring,” the researchers wrote.

“Everyone knows tears have a lot to mine,” Shih said. “The question is, whether you have a detector that is capable of mining it, and how significant is it for real diagnostics.”

In addition to Shih, authors on the paper include Yeon Sik Jung, Jae Won Jeong and Kwang-Min Baek, all with the Korea Advanced Institute of Science and Technology; Seung Yong Lee of the Korea Institute of Science and Technology, and Md Masud Parvez Arnob of UH.

Although non-invasive glucose sensing is just one potential application of the technology, Shih said it provided a good way to prove the technology. “It’s one of the grand challenges to be solved,” he said. “It’s a needle in a haystack challenge.”

Scientists know that glucose is present in tears, but Shih said how tear glucose levels correlate with blood glucose levels hasn’t been established. The more important finding, he said, is that the structure is an effective mechanism for using surface-enhanced Raman scattering spectroscopy.

Although traditional nanofabrication techniques rely on a hard substrate – usually glass or a silicon wafer – Shih said researchers wanted a flexible nanostructure, which would be more suited to wearable electronics. The layered nanoarray was produced on a hard substrate but lifted off and printed onto a soft contact, he said.

Here’s a link to and a citation for the paper,

Wafer Scale Phase-Engineered 1T- and 2H-MoSe2/Mo Core–Shell 3D-Hierarchical Nanostructures toward Efficient Electrocatalytic Hydrogen Evolution Reaction by Yindong Qu, Henry Medina, Sheng-Wen Wang, Yi-Chung Wang, Chia-Wei Chen, Teng-Yu Su, Arumugam Manikandan, Kuangye Wang, Yu-Chuan Shih, Je-Wei Chang, Hao-Chung Kuo, Chi-Yung Lee, Shih-Yuan Lu, Guozhen Shen, Zhiming M. Wang, and Yu-Lun Chueh. Advanced Materials DOI: 10.1002/adma.201602697 Version of Record online: 26 SEP 2016

© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

This paper is behind a paywall.

Using light to make gold crystal nanoparticles

Gold crystal nanoparticles? Courtesy: University of Florida

Gold crystal nanoparticles? Courtesy: University of Florida

A team from the University of Florida has used gold instead of silver in a process known as plasmon-driven synthesis. From a July 8, 2016 news item on phys.org,

A team of University of Florida researchers has figured out how gold can be used in crystals grown by light to create nanoparticles, a discovery that has major implications for industry and cancer treatment and could improve the function of pharmaceuticals, medical equipment and solar panels.

A July 6, 2016 University of Florida news release, which originated the news item, provides more detail,

Nanoparticles can be “grown” in crystal formations with special use of light, in a process called plasmon-driven synthesis. However, scientists have had limited control unless they used silver, but silver limits the uses for medical technology. The team is the first to successfully use gold, which works well within the human body, with this process.

“How does light actually play a role in the synthesis? [This knowledge] was not well developed,” said David Wei, an associate professor of chemistry who led the research team. “Gold was the model system to demonstrate this.”

Gold is highly desired for nanotechnology because it is malleable, does not react with oxygen and conducts heat well. Those properties make gold an ideal material for nanoparticles, especially those that will be placed in the body.

When polyvinylpyrrolidone, or PVP, a substance commonly found in pharmaceutical tablets, is used in the plasmon-driven synthesis, it enables scientists to better control the growth of crystals. In Wei’s research, PVP surprised the team by showing its potential to relay light-generated “hot” electrons to a gold surface to grow the crystals.

The research describes the first plasmonic synthesis strategy that can make high-yield gold nanoprisms. Even more exciting, the team has demonstrated that visible-range and low-power light can be used in the synthesis. Combined with nanoparticles being used in solar photovoltaic devices, this method can even harness solar energy for chemical synthesis, to make nanomaterials or for general applications in chemistry.

Wei has spent the last decade working in nanotechnology. He is intrigued by its applications in photochemistry and biomedicine, especially in targeted drug delivery and photothermal therapeutics, which is crucial to cancer treatment. His team includes collaborators from Pacific Northwest National Laboratory, where he has worked as a visiting scholar, and Brookhaven National Laboratory. In addition, the project has provided an educational opportunity for chemistry students: one high school student (through UF’s Student Science Training Program), two University scholars who also [sic] funded by the Howard Hughes Medical Institute, five graduate students and two postdocs.

Here’s a link to and a citation for the paper,

Polyvinylpyrrolidone-induced anisotropic growth of gold nanoprisms in plasmon-driven synthesis by Yueming Zhai, Joseph S. DuChene, Yi-Chung Wang, Jingjing Qiu, Aaron C. Johnston-Peck, Bo You, Wenxiao Guo, Benedetto DiCiaccio, Kun Qian, Evan W. Zhao, Frances Ooi, Dehong Hu, Dong Su, Eric A. Stach, Zihua Zhu, & Wei David Wei. Nature Materials (2016) doi:10.1038/nmat4683 Published online 04 July 2016

This paper is behind a paywall.