The Celebrate Princeton Innovation event offers entrepreneurial-minded readers a chance to meet university researchers, including many of the ones featured below, Thursday, November 8, from 5 to 8 p.m. at the Frick Chemistry Lab atrium. Visit for details.

Sparkling Internet

Photo by Sameer A. Khan

A new component of the “quantum internet” is taking shape in the laboratory of Nathalie de Leon in the Department of Electrical Engineering.

She envisions a global quantum network that could transmit information far more securely than today’s networks, but one key challenge stems from the difficulty of transmitting quantum signals over long distances. The signals are fragile and can lose their quantum nature as they travel along optical fibers.

De Leon and her team have created a “quantum repeater” that can be placed at nodes throughout a network to store signals before sending them on the next leg of their journey. But until now it has been difficult to find a material that can store quantum signals long enough to be useful.

To overcome this challenge, the team synthesized a diamond with specific impurities, replacing some of the carbon atoms with silicon. With careful materials processing, the team was able to make these defects, known as silicon vacancies, with a neutral charge. The resulting neutral silicon vacancies have just the right properties for handling quantum signals both as pulses of light for transmission in optical fibers and as electron spins for storage in the repeater.

The eventual goal is to integrate these neutral silicon vacancies with nanophotonic structures to build the components of long-distance quantum information networks.

Better, Cheaper Insulin

Photo by C. Todd Reichart

A novel method for producing insulin at lower cost and with greater efficiency could help provide this life-sustaining medication to the estimated 450 million diabetes sufferers around the world. This new method of making the drug uses artificial, or de novo, proteins created from synthetic genes designed by researchers in the lab of Michael Hecht, a professor of chemistry at Princeton University (pictured above with post-doctoral researcher Shlomo Zarzhitsky).

Insulin is a protein consisting of two peptide chains connected by three bridges in the form of molecular bonds. The drug is currently made by programming the genetic sequence for human insulin into bacteria, which produce human insulin as a long, three-part peptide chain that requires folding to bring the two peptide chains together, followed by the removal of the middle section that links the two chains.

With the new method, researchers replace the middle section with a synthetic sequence encoding an artificial protein. Compared to the current method, the artificial protein brings the two insulin chains together more effectively. Moreover the de novo protein is easier to manufacture, is highly stable, and is easily purified. Unlike the current method, which brings the two chains together correctly about 70 percent of the time, this new method using the artificial protein is nearly 100 percent efficient at making insulin.

Zarzhitsky, working with Hecht, recognized the value of using these artificial proteins, called de novo expression enhancer proteins, or DEEPs, for joining together peptides to make insulin. The technology can also be used to make other proteins and peptides that are difficult to express.

“These are proteins that do not occur in nature,” Zarzhitsky said. “They have advantages in that they are very stable and small, so they do not impose a burden on the bacterial protein expression machinery.”

“The technology represents the application of synthetic biology to the search for therapeutic proteins,” Hecht said.

This research was funded by the New Jersey Health Foundation.

Smart Windows

Photo by David Kelly Crow

A new transparent solar cell technology can turn ordinary windows into energy-efficient “smart” windows, regulating the transmission of sunlight and heat to save energy and improve occupant comfort.

Smart windows can darken on hot days to keep the sun out and rooms cool, or let heat in on cold days while reducing glare and protecting privacy. But these technologies require plugging the smart windows into an electricity source, adding to installation and operating costs.

The self-powered smart window is demonstrated by Yueh-Lin (Lynn) Loo, an engineering professor and director of the Andlinger Center for Energy and the Environment (Loo is center above, with graduate students Nicholas Davy and Melda Sezen-Edmonds). The window includes two components: a solar cell that harvests near-ultraviolet light to produce electricity, and the technology to use that harvested electricity to change the window’s color. This color change with electricity, or “electrochromism,” regulates how much visible light and near-infrared heat enter the window.

Electrochromic windows are commercially available today for high-end new construction and luxury automobiles, where the installation cost and complexity of external wiring can be managed. With the new near-ultraviolet solar cells, external wires can be eliminated.

The fact that these solar cells selectively harness ultraviolet wavelengths differentiates them from existing solar cell technologies that absorb visible and/or infrared light. Solar cells that absorb visible light appear black, while those that absorb infrared light block much of the sun’s heat regardless of the season. Powering smart windows with near-ultraviolet solar cells allows for intelligent control of daytime lighting and solar heating throughout the year, which is particularly useful during winter days when occupants desire the warmth of the sun.

“It will be possible to control the sunlight passing into your home or office using an app on your phone or via a smart thermostat, thereby ensuring ideal comfort, privacy, and energy efficiency at all times,” said Davy, a graduate student who led the development of the near-ultraviolet solar cells as part of his Ph.D. work with Loo.

Beyond powering smart windows, the transparent solar cell technology can enable other wireless low-power consumer products, such as internet-of-things sensors, wearables, and displays.

Controlling Proteins

Photo by Laura Pedrick

A new set of technologies for controlling the aggregation of proteins in living cells could aid the search for cures for Alzheimer’s disease, amyotrophic lateral sclerosis (ALS), and other neurodegenerative conditions. The methods also have potential for a host of other biotechnology applications requiring the control of protein assemblies.

The technologies build on a new paradigm in intracellular organization: Living matter, including the proteins inside cells, can self-organize by condensing into liquid droplets and gels.

These “phase transitions” in living organisms are part of normal functioning, but they can go awry and cause cellular dysfunction and disease, said Clifford Brangwynne, above, an associate professor of chemical and biological engineering.

Brangwynne and his team have developed methods to screen for new drug compounds to treat diseases that involve faulty protein organization. One of these tools, called optoDroplet, uses blue laser light to control the interactions between proteins. Researchers can fire a laser into a precise area of the cell to trigger proteins to cling to each other.

By varying the intensity of the light, the researchers can prompt the proteins to cluster into liquid-like droplets, which over time can mature into solid-like aggregates, mimicking what occurs in neurodegenerative diseases like ALS. The tools recently developed by the team can help researchers learn more about protein interactions and how to control them to restore human health.

Fighting Hepatitis B & E

Team Ploss: Qiang Ding, left,
Ila Nimgaonkar, Alexander Ploss, Lei Wei, and Benjamin Winer will be at the November 8 innovation event. (Photo by Robert Ledesma)

A new approach for discovering antivirals against hepatitis B and E viruses aims to identify new drug candidates for these life-threatening diseases. Building on his lab’s expertise in human liver pathogens, Alexander Ploss and his team have pioneered new screening platforms and new methods to evaluate therapeutic candidates.

Infection with hepatitis B virus damages the liver and can cause liver cancer. This chronic infection, which is spread by direct contact with bodily fluids, affects over 250 million people worldwide. The current therapy suppresses infection but is not a cure, as it must be taken for life.

Hepatitis E virus typically causes an acute infection that lasts just a few weeks, but it can cause liver failure in immuno-compromised individuals and be life-threatening during pregnancy. Most of the world’s 20 million cases occur in developing countries, and the virus is spreading to developed countries through tainted pork. The most common treatment for hepatitis E, ribavirin, cannot be used during pregnancy.

Ploss and his team have developed a new high-throughput screen to identify small molecules capable of interfering with the life cycle of hepatitis B virus, with the goal of providing a cure rather than just a treatment. They have developed a sensitive system for rapidly testing molecules using an inactive virus that does not create a biosafety risk.

For hepatitis E virus, the Princeton researchers have developed a system for culturing the virus in human liver cells in the lab. They can use these infected cells to identify new strategies to attack the virus, and rapidly screen for small molecules that interfere with the viral life cycle.

Once candidate molecules are identified, the team will evaluate them in a variety of state-of-the-art cell culture systems and animal models available in the Ploss lab, which is one of the few labs in the world to produce mice with livers that are susceptible to human hepatitis viruses.


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