Improved biodegradable hydrogels

November 09, 1999

ITHACA, N.Y. -- A Cornell University fiber and biomaterials scientist working with a trio of graduate students has developed novel biodegradable and biologically active hydrogels that can be used for delivering many kinds of medications inside and outside the body. The jellylike substance can be used for anchoring biological substances such as skin and vascular tissues and might even be able to deliver viruses into the body for gene therapy.

"These new biomaterials not only contain enormous amounts of water, which make them more biocompatible with the human body, but also have greater mechanical strengths, integrity and stability than other hydrogels," says C. C. Chu, professor of fiber science in the textiles and apparel department in Cornell's College of Human Ecology and the university's Biomedical Engineering Program. Chu and his graduate students can manipulate various properties of the hydrogels, including how much they swell. Their hydrophilicity (the ability to attract and absorb water) and their hydrophobicity (the ability to repel water) are the chief means by which they control drug release. Strength and biodegradation rates also can be changed over a wide range.

The hydrogels not only are useful for controlling and delivering medications and serving as biodegradable networks for implants, tissue engineering and regeneration but also may have applications for coatings in agricultural products. They might even be used for coating fabrics, such as diapers, to absorb liquid, says Chu, whose research on the biodegradable hydrogels will appear in coming months in two scientific journals.

Jellylike hydrogels, non-biodegradable polymers like polyacrylates, can absorb and retain many times their weight without dissolving. They are commonly used as food-thickening agents, coatings for textiles and contact lenses, wound dressings and for delivering medications. Chu has engineered two much stronger and versatile hydrogels -- both have patents pending -- by chemically combining synthetic biodegradable polymers like polylactide and dextran, a polymer of sucrose commonly produced in fermentation, and carbohydrates called polysaccharides.

In one of the new hydrogel inventions from his lab, Chu combined dextran and maleic acid to develop one type of hydrogel that can increase its swelling without lessening its structural stability and mechanical strength. These properties allow the controlled release of medications with large or small molecular weights, such as peptides and proteins that are normally difficult to deliver through diffusion from non-biodegradable carriers.

About the other new class of hydrogel inventions from his lab that has both polysaccharide and synthetic biodegradable components, Chu says: "We have found that the release profile of medications is not only controlled by molecular weight but also by manipulating the composition ratio of these two hydrogel components. Thus, we can develop a release profile to suit any medication or rate of release we want."

Chu and his students have used these hydrogels to deliver the anti-inflammatory drug indomethacin and the cancer drug doxorubicin as well as human insulin and bovine serum albumin. A paper on one of the hydrogels will be published in the Journal of Biomedical Materials Research this year. Chu's co-authors are graduate students Sin-Hee Kim and Chee-Youb Won.

Another hydrogel, both biologically active and biodegradable, is derived from dextran and synthetic biodegradable polylactides. Chu says it can serve as a three -dimensional porous network with a large surface area on which to anchor cells and tissues like skin, cartilage, compounds for healing wounds and repairing blood vessels and introducing viruses in gene therapy. The porous 3-D network hydrogel not only provides much more surface area than currently used nonwoven fiber-based substrates but also has controllable pore sizes. In addition, the hydrogel has sites onto which bioactive substances, such as materials for tissue engineering, can be attached. It is engineered by forcing together a natural and a synthetic compound to form an homogenous gel that does not separate and has both hydrophilic and hydrophobic properties.

A paper on this hydrogel will be published early next year in the Journal of Polymer Sciences, Polymer Chemistry. Chu's co-authors are graduate students Yeli Zhang and Won.

Chu also is working with undergraduate student Renee Wong of Honolulu on testing the hydrogels as a coating for textiles and agricultural applications. The hope is that coated fabrics could be used to absorb sweat or urine in diapers or incontinence products.

Chu reported on both hydrogels last August at the American Chemical Society annual meeting in New Orleans.
-end-
Related World Wide Web sites: The following sites provide additional information on this news release. Some might not be part of the Cornell University community, and Cornell has no control over their content or availability.

-- For more information about C.C. Chu:

http://www.human.cornell.edu/faculty/facultybio.cfm?netid=cc62&facs=1

-- For more information about the College of Human Ecology, see

http://www.human.cornell.edu/

-- For mroe about the Department of Textiles and Apparel, see

http://www.human.cornell.edu/txa/index.cfm

Cornell University

Related Gene Therapy Articles from Brightsurf:

Risk of AAV mobilization in gene therapy
New data highlight safety concerns for the replication of recombinant adeno-associated viral (rAAV) vectors commonly used in gene therapy.

Discovery challenges the foundations of gene therapy
An article published today in Science Translational Medicine by scientists from Children's Medical Research Institute has challenged one of the foundations of the gene therapy field and will help to improve strategies for treating serious genetic disorders of the liver.

Gene therapy: Novel targets come into view
Retinitis pigmentosa is the most prevalent form of congenital blindness.

Gene therapy targets inner retina to combat blindness
Batten disease is a group of fatal, inherited lysosomal storage disorders that predominantly affect children.

New Human Gene Therapy editorial: Concern following gene therapy adverse events
Response to the recent report of the deaths of two children receiving high doses of a gene therapy vector (AAV8) in a Phase I trial for X-linked myotubular myopathy (MTM).

Restoring vision by gene therapy
Latest scientific findings give hope for people with incurable retinal degeneration.

Gene therapy/gene editing combo could offer hope for some genetic disorders
A hybrid approach that combines elements of gene therapy with gene editing converted an experimental model of a rare genetic disease into a milder form, significantly enhancing survival, shows a multi-institutional study led by the University of Pennsylvania and Children's National Hospital in Washington, D.C.

New technology allows control of gene therapy doses
Scientists at Scripps Research in Jupiter have developed a special molecular switch that could be embedded into gene therapies to allow doctors to control dosing.

Gene therapy: Development of new DNA transporters
Scientists at the Institute of Pharmacy at Martin Luther University Halle-Wittenberg (MLU) have developed new delivery vehicles for future gene therapies.

Gene therapy promotes nerve regeneration
Researchers from the Netherlands Institute for Neuroscience and the Leiden University Medical Center have shown that treatment using gene therapy leads to a faster recovery after nerve damage.

Read More: Gene Therapy News and Gene Therapy Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.