Tag Archives: bone-replacement material

Replacing human tissue with nanostructured rubber-like material?

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The scientists started out with an idea for creating a bone-like material)and ended up with something completely different. A March 16, 2020 news item on ScienceDaily announces news about a new material that could be used to replace human tissue,

Researchers from Chalmers University of Technology, Sweden, have created a new, rubber-like material with a unique set of properties, which could act as a replacement for human tissue in medical procedures. The material has the potential to make a big difference to many people’s lives. The research was recently published in the highly regarded scientific journal ACS Nano.

In the development of medical technology products, there is a great demand for new naturalistic materials suitable for integration with the body. Introducing materials into the body comes with many risks, such as serious infections, among other things. Many of the substances used today, such as Botox, are very toxic. There is a need for new, more adaptable materials.

In the new study, the Chalmers researchers developed a material consisting solely of components that have already been shown to work well in the body.

A March 17, 2020 Chalmers University of Technology press release (also on EurekAlert but published on March 16, 2020), which originated the news item, describes the scientists’ surprising discovery and how they shifted their focus,

The foundation of the material is the same as plexiglass, a material which is common in medical technology applications. Through redesigning its makeup, and through a process called nanostructuring, they gave the newly patented material a unique combination of properties. The researchers’ initial intention was to produce a hard bone-like material, but they were met with surprising results.

“We were really surprised that the material turned to be very soft, flexible and extremely elastic. It would not work as a bone replacement material, we concluded. But the new and unexpected properties made our discovery just as exciting,” says Anand Kumar Rajasekharan, PhD in Materials Science and one of the researchers behind the study.

The results showed that the new rubber-like material may be appropriate for many applications which require an uncommon combination of properties – high elasticity, easy processability, and suitability for medical uses.

“The first application we are looking at now is urinary catheters. The material can be constructed in such a way that prevents bacteria from growing on the surface, meaning it is very well suited for medical uses,” says Martin Andersson, research leader for the study and Professor of Chemistry at Chalmers.

The structure of the new nano-rubber material allows its surface to be treated so that it becomes antibacterial, in a natural, non-toxic way. This is achieved by sticking antimicrobial peptides – small proteins which are part of our innate immune system – onto its surface. This can help reduce the need for antibiotics, an important contribution to the fight against growing antibiotic resistance.

Because the new material can be injected and inserted via keyhole surgery, it can also help reduce the need for drastic surgery and operations to rebuild parts of the body. The material can be injected via a standard cannula as a viscous fluid, so that it forms its own elastic structures within the body. Or, the material can also be 3D printed into specific structures as required.

“There are many diseases where the cartilage breaks down and friction results between bones, causing great pain for the affected person. This material could potentially act as a replacement in those cases,” Martin Andersson continues.

A further advantage of the material is that it contains three-dimensionally ordered nanopores. This means it can be loaded with medicine, for various therapeutic purposes such as improving healing and reducing inflammation. This allows for localised treatment, avoiding, for example, having to treat the entire body with drugs, something that could help reduce problems associated with side effects. Since it is non-toxic, it also works well as a filler – the researchers see plastic surgery therefore as another very interesting potential area of application for the new material.

“I am now working full time with our newly founded company, Amferia, to get the research out to industry. I have been pleased to see a lot of real interest in our material. It’s promising in terms of achieving our goal, which is to provide real societal benefit,” Anand concludes.

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The path of the research to societal benefit and commercialisation, through start-up company Amferia and Chalmers Ventures

In order for the discovery of the new material to be useful and commercialised, the researchers patented their innovation before the study was published. The patent is owned by start-up company Amferia, which was founded by Martin Andersson and Anand Kumar Rajasekharan, two of the researchers behind the study, as well as researcher Saba Atefyekta who recently completed a PhD in Materials Science at Chalmers. Anand is now CEO of Amferia and will drive the application of the new material and development of the company.

Amferia has previously been noted for an antibacterial wound patch developed by the same team. Amferia now has the innovation of both the new nano-rubber and the antibacterial wound patch. The development of the company and the innovations’ path to making profit are now being carried out in collaboration with Chalmers Ventures, a subsidiary of Chalmers University of Technology.

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

Tough Ordered Mesoporous Elastomeric Biomaterials Formed at Ambient Conditions by Anand K. Rajasekharan, Christoffer Gyllensten, Edvin Blomstrand, Marianne Liebi, Martin Andersson. ACS Nano 2020, 14, 1, 241-254 DOI: https://doi.org/10.1021/acsnano.9b01924 Publication Date:December 17, 2019 Copyright © 2019 American Chemical Society

This paper is behind a paywall.

Graphene in the bone

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An international team of US, Brazilian, and Indian scientists has developed a graphene-based material they believe could be used in bone implants. From a Sept. 2, 2016 news item on ScienceDaily,

Flakes of graphene welded together into solid materials may be suitable for bone implants, according to a study led by Rice University scientists.

The Rice lab of materials scientist Pulickel Ajayan and colleagues in Texas, Brazil and India used spark plasma sintering to weld flakes of graphene oxide into porous solids that compare favorably with the mechanical properties and biocompatibility of titanium, a standard bone-replacement material.

A Sept. 2, 2016 Rice University news release (also on EurekAlert), which originated the news item, explains the work in more detail,

The researchers believe their technique will give them the ability to create highly complex shapes out of graphene in minutes using graphite molds, which they believe would be easier to process than specialty metals.

“We started thinking about this for bone implants because graphene is one of the most intriguing materials with many possibilities and it’s generally biocompatible,” said Rice postdoctoral research associate Chandra Sekhar Tiwary, co-lead author of the paper with Dibyendu Chakravarty of the International Advanced Research Center for Powder Metallurgy and New Materials in Hyderabad, India. “Four things are important: its mechanical properties, density, porosity and biocompatibility.”

Tiwary said spark plasma sintering is being used in industry to make complex parts, generally with ceramics. “The technique uses a high pulse current that welds the flakes together instantly. You only need high voltage, not high pressure or temperatures,” he said. The material they made is nearly 50 percent porous, with a density half that of graphite and a quarter of titanium metal. But it has enough compressive strength — 40 megapascals — to qualify it for bone implants, he said. The strength of the bonds between sheets keeps it from disintegrating in water.

The researchers controlled the density of the material by altering the voltage that delivers the highly localized blast of heat that makes the nanoscale welds. Though the experiments were carried out at room temperature, the researchers made graphene solids of various density by raising these sintering temperatures from 200 to 400 degrees Celsius. Samples made at local temperatures of 300 C proved best, Tiwary said. “The nice thing about two-dimensional materials is that they give you a lot of surface area to connect. With graphene, you just need to overcome a small activation barrier to make very strong welds,” he said.

With the help of colleagues at Hysitron in Minnesota, the researchers measured the load-bearing capacity of thin sheets of two- to five-layer bonded graphene by repeatedly stressing them with a picoindenter attached to a scanning electron microscope and found they were stable up to 70 micronewtons. Colleagues at the University of Texas MD Anderson Cancer Center successfully cultured cells on the material to show its biocompatibility. As a bonus, the researchers also discovered the sintering process has the ability to reduce graphene oxide flakes to pure bilayer graphene, which makes them stronger and more stable than graphene monolayers or graphene oxide.

“This example demonstrates the possible use of unconventional materials in conventional technologies,” Ajayan said. “But these transitions can only be made if materials such as 2-D graphene layers can be scalably made into 3-D solids with appropriate density and strength.

“Engineering junctions and strong interfaces between nanoscale building blocks is the biggest challenge in achieving such goals, but in this case, spark plasma sintering seems to be effective in joining graphene sheets to produce strong 3-D solids,” he said.

The researchers have produced an animation depicting of graphene oxide layers being stacked,

A molecular dynamics simulation shows how graphene oxide layers stack when welded by spark plasma sintering. The presence of oxygen molecules at left prevents the graphene layers from bonding, as they do without oxygen at right. Courtesy of the Ajayan and Galvão groups

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

3D Porous Graphene by Low-Temperature Plasma Welding for Bone Implants by Dibyendu Chakravarty, Chandra Sekhar Tiwary, Cristano F. Woellner, Sruthi Radhakrishnan4, Soumya Vinod, Sehmus Ozden, Pedro Alves da Silva Autreto, Sanjit Bhowmick, Syed Asif, Sendurai A Mani, Douglas S. Galvao, and Pulickel M. Ajayan. Advanced Materials DOI: 10.1002/adma.201603146 Version of Record online: 26 AUG 2016

© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

This paper is behind a paywall.