Tag Archives: Xin Zhang

Photonic cellulose nanocrystals (CNC) for flexible sweat sensor

It turns out there’s also a hydrogel aspect to this story about a flexible sweat sensor. As for cellulose nanocrystals (CNC), Canada played a leading role in the development of this nanomaterial and I have a bit more about the Canadian CNC scene later in this posting following the link and citation for the research paper. On to the research,

Highly elastic hydrogels constructed by heat-induced hydrogen bond remodeling can switch between wet and dry states (Image by ZHANG Fusheng and LI Qiongya)

A May 8, 2023 news item on phys.org features this work from the Dalian Institute of Chemical Physics of the Chinese Academy Sciences,

Cellulose nanocrystal (CNC), an emerging bio-based material, has been widely applied in fields such as electronics, bioplastics and energy. However, the functional failure of such materials in wet or liquid environments inevitably impairs their development in biomedicine, membrane separation, environmental monitoring, and wearable devices.

Now, a research group led by Prof. Qing Guangyan from the Dalian Institute of Chemical Physics (DICP) of the Chinese Academy of Sciences [CAS] reported a sustainable, insoluble, and chiral photonic cellulose nanocrystal patch for calcium ion (Ca2+) sensing in sweat.

A May 4, 2023 Dalian Institute of Chemical Physics of the Chinese Academy Sciences press release (also on EurekAlert but published May 8, 2023), which originated the news item, provides more detail about the work,

The researchers developed a simple and efficient method to fabricate insoluble CNC-based hydrogels. They found that by utilizing intermolecular hydrogen bond reconstruction, thermal dehydration enabled the optimized CNC composite photonic film to form a stable hydrogel network in an aqueous solution. Moreover, they indicated that the hydrogel could be reversibly switched between dry and wet states, which was convenient for specific functionalization.

The introduction of functionalized molecules by adsorption swelling in a liquid environment resulted in a hydrogel with freeze resistance (–20°C), strong adhesion, good biocompatibility, and high sensitivity to Ca2+.

“This work is expected to facilitate the application of sustainable cellulose sensors to monitor other metabolites (i.e., glucose, urea, and vitamins, etc.),” said Prof. QING. “It also lays foundation for digitally controlled hydrogel systems operating in environment monitoring, membrane separation, and wearable devices.”

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

Sustainable, Insoluble, and Photonic Cellulose Nanocrystal Patches for Calcium Ion Sensing in Sweat by Qiongya Li, Chenchen He, Cunli Wang, Yuxiao Huang, Jiaqi Yu, Chunbo Wang, Wei Li, Xin Zhang, Fusheng Zhang, Guangyan Qing. small DOI: https://doi.org/10.1002/smll.202207932 First published online: 13 April 2023

This paper is behind a paywall.

FPInnovations is a Canadian research and development (R&D) not-for profit organization that was instrumental in the development of CNC. (If memory serves, they are a spinoff from the University of British Columbia.) There are two Canadian CNC production facilities (that I know of): CelluForce in Québec and Blue Goose Biorefineries in Saskatchewan. I get more information about research into applications for CNC from other parts of the world while the Canadian scene remains mostly silent.

A cluster of golden nanoscale stars

A bio-inspired molecule that directs gold atoms to form perfect nanoscale stars? According to a March 30, 2022 news item on Nanowerk, that’s exactly what researchers have done (Note: Links have been removed),

Researchers from Pacific Northwest National Laboratory (PNNL) and the University of Washington (UW) have successfully designed a bio-inspired molecule that can direct gold atoms to form perfect nanoscale stars.

The work (Angewandte Chemie, “Peptoid-Directed Formation of Five-Fold Twinned Au Nanostars through Particle Attachment and Facet Stabilization”) is an important step toward understanding and controlling metal nanoparticle shape and creating advanced materials with tunable properties.

Artistic rendering of gold star assembly. Credit: Biao Jin Courtesy: University of Washington

I do love the fanciful addition of a panda to the proceedings. Thank you Biao Jin.

A March 29, 2022 University of Washington news release (also on EurekAlert but published on March 30, 2022), which originated the news item, provides more detail about the research,

Metallic nanomaterials have interesting optical properties, called plasmonic properties, says Chun-Long Chen, who is a PNNL senior research scientist, UW affiliate professor of chemical engineering and of chemistry, and UW–PNNL Faculty Fellow. In particular, star-shaped metallic nanomaterials are already known to exhibit unique enhancements that are useful for sensing and the detection of pathogenic bacteria, among other national security and health applications.

To create these striking nanoparticles, the team carefully tuned sequences of peptoids, a type of programmable protein-like synthetic polymer. “Peptoids offer a unique advantage in achieving molecular-level controls,” says Chen. In this case, the peptoids guide small gold particles to attach and relax to form larger five-fold twinned ones, while also stabilizing the facets of the crystal structure. Their approach was inspired by nature, where proteins can control the creation of materials with advanced functionalities.

Jim De Yoreo and Biao Jin used advanced in situ transmission electron microscopy (TEM) to “see” the stars’ formation in solution at the nanoscale. The technique both provided an in-depth mechanistic understanding of how peptoids guide the process and revealed the roles of particle attachment and facet stabilization in controlling shape. De Yoreo is a Battelle Fellow at PNNL and affiliate professor of materials science and engineering at UW, and Jin is a postdoctoral research associate at PNNL.

Having assembled their nanoscale constellation, the researchers then employed molecular dynamics simulations to capture a level of detail that can’t be gleaned from experiments — and to illuminate why specific peptoids controlled the formation of the perfect stars. Xin Qi, a chemical engineering postdoctoral researcher in professor Jim Pfaendtner’s group, led this work at UW. Qi used UW’s Hyak supercomputer cluster to model interfacial phenomena between several different peptoids and particle surfaces.

The simulations play a critical role in learning how to design plasmonic nanomaterials that absorb and scatter light in unique ways. “You need to have a molecular-level understanding to form this nice star-shaped particle with interesting plasmonic properties,” said Chen. Simulations can build the theoretical understanding around why certain peptoids create certain shapes.

The researchers are working toward a future where simulations guide experimental design, in a cycle the team hopes will lead to predictive synthesis of nanomaterials with desired plasmonic enhancements. In this aspect, they would like to first use computational tools to identify peptoid side chains and sequences with desired facet selectivity. Then they would employ state-of-art in situ imaging techniques, such as liquid-cell TEM [transmission electron microscope], to monitor the direct facet expression, stabilization, and particle attachment. In other words, Chen says, “If someone can tell us that a structure of plasmonic nanomaterials has interesting optical properties, can we use a peptoid-based approach to predictably make that?”

Though they’re not to that point, this successful experimental–computational work certainly gets them closer. Further, the team’s ability to synthesize nice star shapes consistently is an important step; more-homogeneous particles translate into more-predictable optical properties.

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

Peptoid-Directed Formation of Five-Fold Twinned Au Nanostars through Particle Attachment and Facet Stabilization by Biao Jin, Feng Yan, Xin Qi, Bin Cai, Jinhui Tao, Xiaofeng Fu, Susheng Tan, Peijun Zhang, Jim Pfaendtner, Nada Y. Naser, François Baneyx, Xin Zhang, James J. DeYoreo, Chun-Long Chen. Angewandte Chemie DOI: https://doi.org/10.1002/anie.202201980 First published: 15 February 2022

This paper is open access.

Killing mosquitos and other pests with genetics-based technology

Having supplied more than one tasty meal for mosquitos (or, as some prefer, mosquitoes), I am not their friend but couldn’t help but wonder about unintended consequences (as per Max Weber) on reading about a new patent awarded to Kansas State University (from a Nov. 12, 2014 news item on Nanowerk),

Kansas State University researchers have developed a patented method of keeping mosquitoes and other insect pests at bay.

U.S. Patent 8,841,272, “Double-Stranded RNA-Based Nanoparticles for Insect Gene Silencing,” was recently awarded to the Kansas State University Research Foundation, a nonprofit corporation responsible for managing technology transfer activities at the university. The patent covers microscopic, genetics-based technology that can help safely kill mosquitos and other insect pests.

A Nov. 12, 2014 Kansas State University news release, which originated the news item, provides more detail about the research,

Kun Yan Zhu, professor of entomology; Xin Zhang, research associate in the Division of Biology; and Jianzhen Zhang, visiting scientist from Shanxi University in China, developed the technology: nanoparticles comprised of a nontoxic, biodegradable polymer matrix and insect derived double-stranded ribonucleic acid, or dsRNA. Double-stranded RNA is a synthesized molecule that can trigger a biological process known as RNA interference, or RNAi, to destroy the genetic code of an insect in a specific DNA sequence.

The technology is expected to have great potential for safe and effective control of insect pests, Zhu said.

“For example, we can buy cockroach bait that contains a toxic substance to kill cockroaches. However, the bait could potentially harm whatever else ingests it,” Zhu said. “If we can incorporate dsRNA specifically targeting a cockroach gene in the bait rather than a toxic substance, the bait would not harm other organisms, such as pets, because the dsRNA is designed to specifically disable the function of the cockroach gene.”

Researchers developed the technology while looking at how to disable gene functions in mosquito larvae. After testing a series of unsuccessful genetic techniques, the team turned to a nanoparticle-based approach.

Once ingested, the nanoparticles act as a Trojan horse, releasing the loosely bound dsRNA into the insect gut. The dsRNA then triggers a genetic chain reaction that destroys specific messenger RNA, or mRNA, in the developing insects. Messenger RNA carries important genetic information.

In the studies on mosquito larvae, researchers designed dsRNA to target the mRNA encoding the enzymes that help mosquitoes produce chitin, the main component in the hard exoskeleton of insects, crustaceans and arachnids.

Researchers found that the developing mosquitoes produced less chitin. As a result, the mosquitoes were more prone to insecticides as they no longer had a sufficient amount of chitin for a normal functioning protective shell. If the production of chitin can be further reduced, the insects can be killed without using any toxic insecticides.

While mosquitos were the primary insect for which the nanoparticle-based method was developed, the technology can be applied to other insect pests, Zhu said.

“Our dsRNA molecules were designed based on specific gene sequences of the mosquito,” Zhu said. “You can design species-specific dsRNA for the same or different genes for other insect pests. When you make baits containing gene-specific nanoparticles, you may be able to kill the insects through the RNAi pathway. We see this having really broad applications for insect pest management.”

The patent is currently available to license through the Kansas State University Institute for Commercialization, which licenses the university’s intellectual property. The Institute for Commercialization can be contacted at 785-532-3900 and ic@k-state.edu.

Eight U.S. patents have been awarded to the Kansas State University Research Foundation in 2014 for inventions by Kansas State University researchers.

Here’s an image of the ‘Trojan horse’ nanoparticles,

The nanoparticles, pictured as gold colored, are less than 100 nanometers in diameter. photo credit: bogdog Dan via photopincc

The nanoparticles, pictured as gold colored, are less than 100 nanometers in diameter. photo credit: bogdog Dan via photopincc

My guess is that the photographer has added some colour such as the gold and the pink to enhance the image as otherwise this would be a symphony of grey tones.

So, if this material will lead to weakened chitin such that pesticides and insecticides are more effective, does this mean that something else in the food chain will suffer because it no longer has mosquitos and other pests to munch on?

One last note, usually my ‘mosquito’ pieces concern malaria and the most recent of those was a Sept. 4, 2014 posting about a possible malaria vaccine being developed at the University of Connecticut.