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May 27, 2002
Volume 80, Number 21
CENEAR 80 21 p. 14
ISSN 0009-2347


Material formed at low concentration could find use in tissue engineering

A new type of peptidic hydrogel scaffold forms at polymer concentrations as low as 0.25 to 2.0% by weight, according to researchers at the Materials Research Laboratory at the University of California, Santa Barbara, and the department of materials science and engineering at the University of Delaware, Newark [Nature, 417, 424 (2002)]. The new hydrogels could be used in drug delivery and tissue engineering applications.

SCAFFOLD A hydrogel consisting of a 160-amino-acid poly-l-lysine block and a 40-amino-acid poly-l-valine block is shown in this laser scanning confocal micrograph. Fluorescent dye was added to the assembling gel, showing where the polypeptide is. Scale bar = 20 µm.
The hydrogels are diblock copolypeptides with hydrophilic and hydrophobic regions. Usually, such a combination of hydrophilic and hydrophobic portions forms micelles, but not in this material. The hydrophobic polypeptide segments can be made to adopt different chain conformations, similar to those found in proteins, says team leader Timothy J. Deming of UCSB. "Ordered chain structures cannot pack efficiently into spheres" and so don't form micelles. Team members include, among others, graduate student Andrew P. Nowak at UCSB and Darrin Pochan, assistant professor at Delaware.

One problem with protein hydrogels produced from natural sources is their variability. "Our polymers are simple to prepare with consistent properties," Deming says. "They contain only natural amino acids and should be enzymatically degradable. The gel formation process is very benign and straightforward--just add water."

The work "opens up a new avenue not only in the synthesis of highly effective gel-forming polymers, but also in the synthesis of extremely stable micelles," says Kinam Park, professor of biomedical engineering and pharmaceutics at Purdue University, who studies hydrogels for drug delivery applications. "It will be interesting to test whether such a gel-forming property is maintained at physiological conditions."


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Copyright © 2002 American Chemical Society

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