Stronger than Steel, Tougher than Kevlar

Spider silk is said to be one of the strongest, toughest materials on the Earth. Now engineers at Washington University in St. Louis have designed amyloid silk hybrid proteins and produced them in engineered bacteria. The resulting fibers are stronger and tougher than some natural spider silks.

To be precise, the artificial silk — dubbed “polymeric amyloid” fiber — was not technically produced by researchers, but by bacteria that were genetically engineered in the lab of Fuzhong Zhang, a professor in the Department of Energy, Environmental & Chemical Engineering in the McKelvey School of Engineering.

Zhang has worked with spider silk before. In 2018, his lab engineered bacteria that produced a recombinant spider silk with performance on par with its natural counterparts in all of the important mechanical properties.

After our previous work, I wondered if we could create something better than spider silk using our synthetic biology platform,” Zhang said.

The research team, which includes first author Jingyao Li, a PhD student in Zhang’s lab, modified the amino acid sequence of spider silk proteins to introduce new properties, while keeping some of the attractive features of spider silk.

A problem associated with recombinant spider silk fiber — without significant modification from natural spider silk sequence — is the need to create β-nanocrystals, a main component of natural spider silk, which contributes to its strength. “Spiders have figured out how to spin fibers with a desirable amount of nanocrystals,” Zhang said. “But when humans use artificial spinning processes, the amount of nanocrystals in a synthetic silk fiber is often lower than its natural counterpart.

Their research was published in the journal ACS Nano.

Source: https://source.wustl.edu/

Nano-Transistor From DNA-like Material

Computer chips use billions of tiny switches, called transistors, to process information. The more transistors on a chip, the faster the computer. A material shaped like a one-dimensional DNA helix might further push the limits on a transistor’s size. The material comes from a rare earth element called tellurium.

Researchers found that the material, encapsulated in a nanotube made of boron nitride, helps build a field-effect transistor with a diameter of two nanometers. Transistors on the market are made of bulkier silicon and range between 10 and 20 nanometers in scale.  Engineers at Purdue University performed the work in collaboration with Michigan Technological University, Washington University in St. Louis, and the University of Texas at Dallas.

Over the past few years, transistors have been built as small as a few nanometers in lab settings. The goal is to build transistors the size of atomsPeide Ye’s lab at Purdue is one of many research groups seeking to exploit materials much thinner than silicon to achieve both smaller and higher-performing transistors.

These silver, wiggling lines are strings of atoms in tellurium behaving like DNA. Researchers have not seen this behavior in any other material.

This tellurium material is really unique. It builds a functional transistor with the potential to be the smallest in the world,” said Ye, Purdue’s Richard J. and Mary Jo Schwartz Professor of Electrical and Computer Engineering.

The research is published in the journal Nature Electronics.

Source: https://www.purdue.edu/

Simple Blood Test Will Diagnose Alzheimer’s Next Year

(from Bill Gates blog) How do you stop Alzheimer’s disease without a simple way to diagnose it? It’s a real chicken and egg problem, as I wrote last year on TGN. Discovering a treatment for Alzheimer’s requires lots of clinical trials for new drugs—but it’s difficult to enroll participants without a way to identify people who have the disease early enough for potential treatments to work.

Right now, the best way to diagnose the disease is through a spinal tap or a brain scan. The problem is that the former is invasive and the latter is expensive. Plus, many patients don’t get these tests until they start showing signs of cognitive decline, which means the disease may already be pretty advanced. It’s hard to overstate how important finding a reliable, affordable, and easy-to-use diagnostic is for stopping Alzheimer’s.

The good news is that we’re finally within reach of that goal thanks to significant breakthroughs over the last couple years. Scientists are pushing forward with new diagnostics that range from simple blood tests to voice analysis straight out of a sci-fi novel. We’re close to reaching the point where we can push past the chicken and egg problem.

That’s why I announced last summer that I was investing in a new fund with the Alzheimer’s Drug Discovery Foundation called Diagnostics Accelerator, which aims to accelerate the progress already underway. I am grateful to be joined in this effort by my friends Jeff and MacKenzie Bezos. They have been tremendous partners who are deeply committed to finding an end to this disease. We’ll continue to work together on finding a new way to diagnose Alzheimer’s, as well as on other efforts, over the coming months. In the meantime, the fund is getting ready to announce the first round of awards.

It wasn’t that long ago that we had no way to test for Alzheimer’s beyond cognitive assessments. The first breakthrough came in the late 1990s and early 2000s, when brain imaging (like a PET scan or MRI) allowed us to see biological changes in the brain of someone with the disease.

Then came the spinal tap in 2006. A team of Swedish scientists—Oskar Hansson, Henrik Zetterberg, and Kaj Blennow—demonstrated that you could predict which patients would develop Alzheimer’s disease by looking at cerebrospinal fluid (the fluid found in the brain and spinal cord). Their discovery gave researchers a more accessible tool to make smarter decisions about who should be in a clinical trial. It wasn’t perfect, though—just ask anyone who’s ever had a spinal tap whether they’re eager to undergo the procedure again.

What does the ideal Alzheimer’s diagnostic look like? It needs to be cheap and easy to administer. It should tell us not only whether you have Alzheimer’s, but how far advanced the disease is. (Your cholesterol test doesn’t just tell you that you have cholesterol, after all—it lets you know how much you have and whether it could be a problem.) Above all, it should be as simple and painless as any of the other routine tests you get during your annual physical. In other words, a blood test would fit the bill.

Enter Randy Bateman, a professor and researcher at Washington University in St. Louis. His team was one of the first to identify changes in the blood of Alzheimer’s patients that remained consistent over many tests. Since he published his research in the summer of 2017, other researchers have released similar findings, and a lot of people are working to perfect the diagnostic (including the Swedish team that discovered the spinal tap test).

There’s a good chance a blood test will start being used to recruit patients into Alzheimer’s drug trials within the next year or two. That’s super exciting, because it means that labs will be able to recruit more patients more quickly, and scientists will be able to figure out whether a drug works in less time. It also means that you’ll one day be able to easily get tested during a routine doctor’s visit.

But what if we could find an even less invasive way to diagnose Alzheimer’s? What if we could use digital technology, not medicine, to identify individuals years before they start to develop mental decline?

Source: https://www.gatesnotes.com/