How hydrogels are changing treatment


A vial of hydrogel. Image: Jeff Fitlow/Rice University

Biocompatibility in the development of new medical treatments is becoming increasingly important. Implants are traditionally made of materials foreign to the human body – from titanium to silicone – that can cause issues with system toxicity that may lead the body to reject the implant.

Like the human body, a significant proportion of the make-up of hydrogels is water – 90% compared to the body’s 60% – making them a viable modern alternative to the current standard of implants.

At the moment, focus is on the development of hydrogels in drug delivery systems, although its potential stretches further.

Inspired by nature

One such example of hydrogel innovation was developed by researchers at the University of Michigan, US, and the University of Fribourg, Switzerland. Finding inspiration from the electric eel, the team created a flexible electrical device that could be used as a power source for implanted health monitors.

The electric eel generates power using transmembrane transport, whereby ion channels control the passage of cations and anions through the membrane in the eel’s electrocytes.

At rest, these ions cancel each other out. However, when triggered, the cation channels become more permeable, shifting the overall potential across the cell. In these instances, the eel can produce up to 600V of electricity.

‘The electric organs in eels are incredibly sophisticated; they’re far better at generating power than we are,’ said Michael Mayer, co-author and Biophysics Professor at the University of Fribourg. ‘But the important thing for us was to replicate the basics of what is happening.’

An electric eel. Image: Scott/Flickr

Firstly, the group dissolved sodium and chloride in the hydrogel and layers built by printing thousands of droplets of the salty gel these were alternated with hydrogel droplets of pure water. Each type of droplet could only conduct cations or anions.

Pressing cells together created a concentration gradient which is stimulated by an external electric current, creating a system similar to the electric eels.

By stacking 2,449 of these cells, Mayer says the hydrogel produced 100W, but the nature of the hydrogel’s internal resistance means the outputs of the cells is only 50µW. The team are now working to improve its efficiency.

‘Maybe the most obvious thing to think as a next step would be to try in some creative way to tap into the existing ionic gradients within the body. Much better of course would be a design where one could tap into metabolic energy to keep an artificial organ always charges,’ said Mayer.

‘That would be the ultimate achievement, but that’s very difficult to reach and we have not approached that part of the problem.’

This is an abridged version of an article by Georgina Hines for SCI – to read the rest of the report, click here.

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Nickel in the X-ray limelightMaking chemicals for industrial…

Nickel in the X-ray limelight

Making chemicals for industrial processes often requires scientists to use a catalyst—a substance that speeds up a chemical reaction, reducing the amount of energy it takes to make different products.

Scientists have long considered palladium, a precious metal closely related to platinum, a star catalyst because of its highly active nature. However, because palladium is so expensive, scientists have been looking for ways to substitute another metal for the majority of the palladium involved in certain catalysts.

In a new study from the U.S. Department of Energy’s (DOE) Argonne National Laboratory and the University of California at Santa Barbara, scientists have identified another elemental actor that helps activate palladium while reducing the amount of the precious metal needed for reactions to occur.

By combining a smaller amount of palladium with nickel on an iron nanoparticle formation, a research team led by Argonne chemist Max Delferro and his colleague Bruce Lipshutz, a chemistry professor at the University of California-Santa Barbara, designed an inexpensive and efficient system that reduced nitro-aryl groups to amines, a chemical group important in agricultural chemicals and the pharmaceutical industry.

Read more.

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Andronovo pastoralists brought steppe ancestry to South Asia (Narasimhan et al. 2018 preprint)

Over at bioRxiv at this LINK. Please note that throughout the preprint the Andronovo samples that are shown to have contributed to the South Asian gene pool are labeled Steppe_MLBA_East (ie. Middle to Late Bronze Age eastern steppe). Below is the abstract. I’ll keep updating this entry throughout the day. Emphasis is mine:

The genetic formation of Central and South Asian populations has been unclear because of an absence of ancient DNA. To address this gap, we generated genome-wide data from 362 ancient individuals, including the first from eastern Iran, Turan (Uzbekistan, Turkmenistan, and Tajikistan), Bronze Age Kazakhstan, and South Asia. Our data reveal a complex set of genetic sources that ultimately combined to form the ancestry of South Asians today. We document a southward spread of genetic ancestry from the Eurasian Steppe, correlating with the archaeologically known expansion of pastoralist sites from the Steppe to Turan in the Middle Bronze Age (2300-1500 BCE). These Steppe communities mixed genetically with peoples of the Bactria Margiana Archaeological Complex (BMAC) whom they encountered in Turan (primarily descendants of earlier agriculturalists of Iran), but there is no evidence that the main BMAC population contributed genetically to later South Asians. Instead, Steppe communities integrated farther south throughout the 2nd millennium BCE, and we show that they mixed with a more southern population that we document at multiple sites as outlier individuals exhibiting a distinctive mixture of ancestry related to Iranian agriculturalists and South Asian hunter-gathers. We call this group Indus Periphery because they were found at sites in cultural contact with the Indus Valley Civilization (IVC) and along its northern fringe, and also because they were genetically similar to post-IVC groups in the Swat Valley of Pakistan. By co-analyzing ancient DNA and genomic data from diverse present-day South Asians, we show that Indus Periphery-related people are the single most important source of ancestry in South Asia — consistent with the idea that the Indus Periphery individuals are providing us with the first direct look at the ancestry of peoples of the IVC — and we develop a model for the formation of present-day South Asians in terms of the temporally and geographically proximate sources of Indus Periphery-related, Steppe, and local South Asian hunter-gatherer-related ancestry. Our results show how ancestry from the Steppe genetically linked Europe and South Asia in the Bronze Age, and identifies the populations that almost certainly were responsible for spreading Indo-European languages across much of Eurasia.

Narasimhan et al, The Genomic Formation of South and Central Asia, Posted March 31, 2018, doi:
Late PIE ground zero now obvious; location of PIE homeland still uncertain, but…
Ancient herders from the Pontic-Caspian steppe crashed into India: no ifs or buts