Tag Archives: Hydrogel

Silk hydrogel battery could power pacemakers in mice

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A small soft lithium-ion battery made from water droplets

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The smallest soft lithium-ion battery ever made consists of just three tiny droplets formed from a silk-based hydrogel. Droplet batteries can provide pacemaker-style control and deliver defibrillator shocks to beating mouse hearts, but could eventually be used in biomedical implants and wearable electronics for humans. It may supply electricity.

“Potentially, our small battery could be used as an implantable microrobotic battery, which could be moved to a target location by a magnetic field and release its energy for treatment.” . Yuka Zhang at Oxford University.

Zhang and colleagues designed the small battery as three connected droplets that can self-assemble in solution after injecting various components into the liquid with a microsyringe. One droplet contains lithium manganese oxide particles and serves as the battery's negative electrode. The second droplet contains lithium titanate particles and serves as the positive electrode. A central droplet filled with lithium chloride separates these electrodes. UV light energizes the battery by breaking down the layers that separate each droplet, allowing lithium ions to flow freely between the droplets.

Droplet batteries are one-tenth the length of traditional soft lithium-ion batteries. At just 600 micrometers, it is about six times as wide as a human hair. The battery is also 1000 times smaller in volume than similar flexible lithium-ion batteries. The central droplet can also incorporate magnetic nickel particles, allowing the battery to be controlled remotely via an external magnetic field.

Such a small battery also provides an unprecedented amount of energy considering its small size. Wei Gao at the California Institute of Technology. “This energy density is significantly higher than what has been achieved with other similarly sized batteries,” he says.

The droplet battery was tested on a mouse heart removed from the animal's body. These successfully functioned as defibrillators to restore normal heartbeats and as pacemakers to regulate heartbeats. Additional testing showed that the battery retained 77% of its original capacity after 10 charge/discharge cycles.

The simplicity and scalability of such droplet batteries could be a potential advantage over traditional battery manufacturing in the future, Gao said. He suggested that such batteries could power minimally invasive biomedical implants and biodegradable medical devices.

“What impressed me most is how this soft battery mirrors the aqueous environment of human tissue by being hydrogel-based,” Gao says. “However, we still need to consider the safety and biocompatibility of the materials used in this battery, especially as we move towards commercialization and further research applications.”

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Source: www.newscientist.com

Hydrogel Extends Drug Shelf Life Beyond Refrigeration

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When mixed with hydrogel, protein-based drugs can remain effective for longer at higher temperatures.

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Many medicines need to be kept refrigerated or they become ineffective, but a new way of packaging protein-based drugs into a stiff gel could potentially extend their shelf life at room temperature.

If medicines are not stored properly, they can break down and become unsafe to use. For example, exposure to high temperatures can break down the chemical bonds that keep the medicine’s molecules in place, impairing their function. Shaking some medicines can cause the molecules to clump together, making them less effective. Matthew Gibson Researchers at the University of Manchester in the UK have been working to solve these challenges for almost 15 years.

He and his colleagues have developed a method to make working with protein-based drugs simpler and more practical. He said the new advances are Dave Adams Hydrogel-making researchers at the University of Glasgow in Scotland have found a way to mix proteins with gel ingredients to create hard, white structures that can be packed into a syringe. In this form, the proteins, which normally must be refrigerated at minus 20 degrees Celsius (minus 4 degrees Fahrenheit), can withstand temperatures of up to 50 degrees Celsius (122 degrees Fahrenheit) and remain functional under those conditions for up to four weeks.

Hydrogels get their stiffness from small molecules bound together in large chains that break when force is applied. In a syringe, pushing down on the plunger breaks the molecular bonds, turning the gel-protein mixture into a liquid. The hydrogel remains too large to fit through the needle, so only the drug comes out.

The team tested the method with several compounds, including bovine insulin and beta-galactosidase, an enzyme commonly used in genetic biology, and mailed themselves boxes filled with tubs of hydrogel packed with the proteins, finding that the proteins could withstand the temperature and jolts that come with going through the postal system.

There are laboratory methods that can keep proteins stable for longer, but this approach may be better suited to leaving the lab and going into the clinic, he said. Alex Brogan The King’s College London researcher says the method would be most useful in countries and regions where refrigeration is scarce and prohibitively expensive. If the new method works for protein-based vaccines, it could make disease prevention more equitable, he says.

Gibson says he and his team are confident they can produce the hydrogel on an industrial scale, but want to study its longevity and safety further. Using it in a vaccine is on their wish list, but in the short term the method could also be used to store, transport and administer the diabetes and obesity drug semaglutide.

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Source: www.newscientist.com