MMaterialsgateNEWS 2017/06/13

Related MaterialsgateCARDS

Mussels add muscle to biocompatible fibers

Credit: Courtesy of the Hartgerink Research Group

Rice chemists develop hydrogel strings using compound found in sea creatures

Rice University chemists can thank the mussel for putting the muscle into their new macroscale scaffold fibers.

The Rice lab of chemist Jeffrey Hartgerink had already figured out how to make biocompatible nanofibers out of synthetic peptides. In new work, the lab is using an amino acid found in the sticky feet of mussels to make those fibers line up into strong hydrogel strings.

Hartgerink and Rice graduate student I-Che Li introduced their room-temperature method this month in an open-access paper in the Journal of the American Chemical Society.

The hydrogel strings can be picked up and moved with tweezers, and Li said he expects they will help labs gain better control over the growth of cell cultures.

“Usually when cells grow on a surface, they spread randomly,” he said. “There are a lot of biomaterials we want to grow in a specific direction. With the hydrogel scaffold aligned, we can expect cells to grow the way we want them to. One example would be neuron cells, which we want to grow head-to-tail to aid nerve regeneration.

“Basically, this could allow us to direct cell growth from here to there,” he said. “That’s why this material is so exciting.”

In previous research Hartgerink’s lab had developed synthetic hydrogels that could be injected into the body to serve as scaffolds for tissue growth. The hydrogels contained hydrophobic peptides that self-assembled into fibers about 6 nanometers wide and up to several microns long. However, because the fibers did not interact with one other, they generally appeared in microscope images as a tangled mass.

Experiments showed the fibers could be coaxed into alignment with the application of shear forces, in the same way that playing cards are aligned during shuffling by pushing on both the top and bottom of the deck.

Hartgerink and Li decided to try pushing the fibers through a needle to force them into alignment, a process that would be easier if the material was water soluble. So they added a chain of amino acids known as DOPA to the sides of the fibers to allow them to remain water-soluble in the syringe, Li said.

DOPA — short for 3,4-dihydroxyphenylalanine — is the compound that lets mussels stick to just about anything. Hartgerink and Li found that the combination of DOPA and shear stress from passing through the needle prompted the fibers to form visible, rope-like bundles.

They also found that DOPA promoted chemical cross-linking reactions that helped the bundles hold their shape. “DOPA is really sensitive to oxidizing agents,” Li said. “Even exposing DOPA to air oxidizes it, and that aids in cross-linking the fibers.”

As a bonus, the aligned fibers also proved to have a curious and useful optical property called “uniform birefringence,” or double-refraction. Li said this could allow researchers to use polarized light to see exactly where the aligned fibers are, even if they’re covered by cells.

“This will be an important technique for us to make sure of the long-range order of fiber alignment when we are testing directed cell growth,” he said.

The researchers expect the aligned fibers can be used for macroscale medical applications but with nanoscale control over the structures.

“Self-assembly is basically the ability of a molecule to make ordered structure from chaos, and what I-Che has done is push this organization to a new level with his aligned strings,” said Hartgerink, a professor of chemistry and of bioengineering. “With this material, we are excited to see if we can impose this organization onto the growth of cells that interact with it.”

Source: Rice University – 09.06.2017.

Investigated and edited by:

Dr.-Ing. Christoph Konetschny, Inhaber und Gründer von Materialsgate
Büro für Material- und Technologieberatung
The investigation and editing of this document was performed with best care and attention.
For the accuracy, validity, availability and applicability of the given information, we take no liability.
Please discuss the suitability concerning your specific application with the experts of the named company or organization.

You want additional material or technology investigations concerning this subject?

Materialsgate is leading in material consulting and material investigation.
Feel free to use our established consulting services

MMore on this topic

Credit: Hokkaido University

Scientists have succeeded in creating 'fiber-reinforced soft composites,' or tough hydrogels combined with woven fiber fabric. These fabrics are highly flexible, tougher than metals, and have a wide range of potential applicattions.

Efforts are currently underway around the world to create materials that are friendly to both society and the environment. Among them are those that comprise different materials, which exhibit the merits of each component. Hokkaido University researchers, led by Professor Jian Ping Gong, have focused on creating a reinforced material using hydrogels. Though such a substance has potential as a structural biomaterial, up until now no material reliable and strong enough for long-term use has been produced. This study was conducted as a part of the Cabinet Office's Impulsing Paradigm Change through Disruptive Technologies Program (ImPACT). To address the problem, the team combined hydrogels... more read more

Researchers at Hokkaido University have developed a new kind of hydrogel that bonds spontaneously and strongly to defected bones, suggesting potential use in the treatments of joint injuries.

When soft supporting human tissues--including cartilage and ligaments, which are joined firmly to bones--are damaged, they cannot spontaneously repair inside the body. The use of artificial supporting tissues has the potential to significantly ameliorate damage to soft tissues. Progress has hitherto been hampered by the lack of materials that are strong, yet soft and pliant, for adhering to bone. The research group had previously developed a tough, high-strength network gel, called double-network gel (DN gel), that exhibited excellent performance such as low wear and inductive function for cartilage regeneration. However, as the gel's main component is water, it was difficult for it... more read more

In research published in Nature Materials, a team led by scientists from the RIKEN Center for Emergent Matter Science in Japan has developed a new hydrogel that works like an artificial muscle--quickly stretching and contracting in response to changing temperature.

They have also managed to use the polymer to build an L-shaped object that slowly walks forward as the temperature is repeatedly raised and lowered. Hydrogels are polymers that can maintain large quantities of water within their networks. Because of this, they can swell and shrink in response to changes in the environment such as voltage, heat, and acidity. In this sense they are actually similar to the plant cells, which are able to change shape as the amount of water within them changes in response to environmental conditions. However, most hydrogels do this very slowly, and must absorb and excrete water to either expand or shrink in volume. The unique property of the hydrogel developed... more read more

MaterialsgateNEWSLETTER

Partner of the Week

Search in MaterialsgateNEWS

Books and products

MaterialsgateFAIR:
LET YOURSELF BE INSPIRED