seal  Purdue News

December 5, 2003

Purdue researchers create templates on retinal tissues

WEST LAFAYETTE, Ind. – Researchers at Purdue University have created scaffold-like patterns on the surface of a pig's retina, making templates out of molecular compounds called peptides that could promote the growth of transplanted healthy cells to treat age-related macular degeneration.

Macular degeneration destroys light-sensing cells in the retina. Researchers at other institutions have hypothesized that placing templates on the retina could enable transplanted cells to take hold and grow.

Biomedical engineers at Purdue used an instrument called an atomic force microscope and a device called a cantilever to lay down lines of peptides in a process known as dip-pen nanolithography. The pattern was permanently attached to a dime-size piece of retina extracted from the eye of a pig, said Albena Ivanisevic, an assistant professor of biomedical engineering and an assistant professor of chemistry at Purdue. The work was not done with live pigs.

"We wanted to demonstrate that we could perform lithography, or patterning, on something other than a metal, semiconductor or insulator surface," Ivanisevic said. "Here we have shown that it can be done on retinal tissue."

Ivanisevic detailed findings in a talk presented Dec. 3 during a meeting of the Materials Research Society in Boston.

"We are interested in making surfaces that can eventually be used for transplant strategies," Ivanisevic said. "It has been proposed that you might implant retinal pigment epithelial cells as a potential treatment for macular degeneration, but the success of such a procedure could be greatly increased if you used some sort of a template or scaffold."

Peptides are made of amino acids, the building blocks of proteins.

The Purdue engineer conducted tests demonstrating that the templates were permanently attached to the retinal tissues, but further work is needed to determine the precise nature of the bonds created and to fashion templates out of various types of peptides.

"The idea is to generate different types of patterns on the surface and test whether they indeed promote the proliferation of retinal pigment epithelial cells and how the surface arrangement of these molecules on the surface affects that," Ivanisevic said.

Each of the lines in the template was less than 100 nanometers wide. "Nano" is a prefix meaning one-billionth, so a nanometer is one-billionth of a meter, or roughly the length of 10 hydrogen atoms strung together.

Macular degeneration is an incurable eye disease that is the leading cause of blindness for people 55 and older in the United States, affecting more than 10 million Americans. Retinal pigment epithelial cells deliver nutrients to the retina and remove waste products. Macular degeneration is caused by a deterioration of these cells.

The research paper was written by Ivanisevic and visiting student Nicole Onyenenho from the University of Maryland.

Ivanisevic is associated with two centers in Purdue's Discovery Park: the Birck Nanotechnology Center and Bindley Bioscience Center, which funded the research, and this work also is supported by the NASA Institute for Nanoelectronics and Computing at Purdue.

Writer: Emil Venere, (765) 494-4709,

Source: Albena Ivanisevic, (765) 496-3676,

Purdue News Service: (765) 494-2096;

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