Elastic, wound-healing hydrogel activated by light

 

Bioengineers have developed a new protein-based gel (not pictured) that mimics many of the properties of elastic tissue when exposed to light (Credit: Shutterstock) Hydrogels have huge potential in the field of biomedicine, but aren't without their shortcomings in their existing form. These tiny polypeptide chains are championed for their many possible applications. Indeed, in the last few years alone we've seen advances that suggest they could find use in generating new heart tissue, fighting off superbugs and the controlled release of anti-inflammatory drugs. But researchers have now developed a hydrogel that mimics the elasticity of human tissue and can be activated by exposure to light, claiming it could offer safer means of repairing wounded tissue. In order to bestow them with enough strength and stability, some hydrogels are treated with chemical compounds, which can then over time see them degrade into harmful materials. Bioengineers at Brigham and Women's Hospital (BHW) in Boston say they have overcome this problem by creating a hydrogel that becomes stronger only once it is exposed to light. They call their new material a photocrosslinkable elastin-like polypeptide-based (ELP) hydrogel. As the gel is exposed to light, its molecules bind together to create a mechanical stability, so much so that it can endure more stretching than that experienced by arterial tissue in the body. Perhaps even more promising was the fact that they could dictate both the level of swelling and strength of the material, suggesting it could prove to have a number of uses. "Our hydrogel has many applications: it could be used as a scaffold to grow cells or it can be incorporated with cells in a dish and then injected to stimulate tissue growth," says Nasim Annabi, PHD at BHW's Biomedical Engineering Division. "In addition, the material can be used as a sealant, sticking to the tissue at the site of injury and creating a barrier over a wound." The gel was found to be consumed by naturally-occurring enzymes over time and had no toxic effects on living cells in the lab. The team also discovered that mixing the gel with silica nanoparticles gave it the ability to more effectively prevent bleeding, something that could allow better protection of a wound and stop bleeding with a single treatment. The scientists say that more pre-clinical studies are required to test the gel's properties and safety before human trials will be possible. The research was published in the journal Advanced Functional Materials. Source: Brigham and Women's Hospital

Hydrogel: Patent issued for substance with medical benefits

 

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Xiuzhi "Susan" Sun, university distinguished professor of grain science and bio- and agro-engineering at Kansas State University, examines a test tube containing a hydrogel. A U.S. patent was recently issued for the Kansas State University developed hydrogel formulas.

A novel jelly-like substance developed by Kansas State University researchers was recently issued a U.S. patent. The substance may be used for biomedical applications, ranging from cell culture and drug delivery to repairing and replacing tissue, organs and cartilage.

U.S. Patent No. 8,835,395, "Novel Protein Peptide Hydrogels," was awarded to the Kansas State University Research Foundation, a nonprofit corporation responsible for managing technology transfer activities at the university.

The patent is licensed by the research foundation to the company PepGel LLC, started by the inventors to explore commercialization opportunities in biomedical research and medical device areas.

The patent is for research conducted by Xiuzhi "Susan" Sun, university distinguished professor of grain science and bio- and agro-engineering, and Hongzhou "John" Huang, a 2012 doctoral graduate. It covers various combinations of short peptides -- compounds created from amino acids -- that can be used to form hydrogels.

A hydrogel is a substance that can transform from a jelly-like state to a liquid-like state. Physically, the hydrogel looks similar to a blob of jelly, although it is less dense because it is composed of nearly 100 percent water.

"When the hydrogel is made, it has a jelly or tofu consistency, but colorless and transparent," Sun said. "But when it is shaken, the gel can become like water and then return to its original state. When we first made it, we had never expected such phenomena and we thought we were onto something interesting."

The hydrogel was created as a spinoff of a separate project -- a protein-based glue that can be used in outer space and other extremely dry environments that Sun developed with Kansas State University's John Tomich, professor of biochemistry. Sun decided to study a fraction of the peptide sequence that gave the glue its adhesive ability by attaching a heterogeneous hydrophilic peptide segment inspired by spider silk proteins.

The newly discovered peptide was formed with 19 amino acids and can self-assemble into 3-D nanofiber networks. These transform into a hydrogel by changing the pH level or introducing an ion, such as a calcium ion.

The nanofiber size and pore size of the hydrogel are in the similar range of a natural extracellular matrix in the biological system. Moreover, the hydrogel was found to have sheer-thinning and self-healing properties -- meaning it could change from a gel to a liquid state and back to a gel again.

In addition to being able to rapidly change forms, the hydrogel formulas created by Sun and Huang are resistant to high temperatures up to 80-degrees Celsius at a neutral pH level.

"This hydrogel system has large variations and flexibility in controlling the gel stiffness, viscoelastic behavior and surface properties," Sun said. "Because of this, the hydrogels may have numerous biomedical research uses and medical device application, including use as scaffolds or artificial extracellular matrix for tissue engineering and healing wounds; cell therapies; combining with stem cells to repair or replace organs; drug delivery; an adjuvant for vaccines; and drug and cell encapsulation."

Sun is currently conducting collaborative research with hydrogels for applications and efficiency with anticancer drugs screening and delivery, stem cells and wound healing, as well as being used in vaccines for H1N1 influenza and animal diseases, such as the porcine reproductive and respiratory syndrome virus, or PRRS.

This hydrogel patent, along with several other patent pending applications, are licensed by the startup company PepGel LLC, which was co-founded by Sun and Huang to make their technology available for research use and medical device applications.

"We are pleased with the international interest in our hydrogel formulas and hope the hydrogels help develop meaningful medical applications that improve wellness, especially in areas such as cancer therapies," said Tim Fealey, CEO of PepGel LLC.

Currently, the Kansas State University Research Foundation has been awarded eight U.S. patents in 2014 for inventions by Kansas State University researchers.