Medical molecules designed to respond to visible light that can penetrate tissue

If you have ever covered a flashlight with your hand and seen the red light that still comes through, then you have seen light in the therapeutic window – that magic wavelength that is not absorbed or reflected away by tissue. Scientists believe that they can use light at that wavelength to signal manmade molecules to release drugs at disease sites in the body.

Such possibilities will be discussed in a poster and a talk by Virginia Tech researchers presenting at the 229th American Chemical Society national meeting in San Diego on March 13-17.

Researchers in Karen Brewer’s group at Virginia Tech have designed supramolecular complexes that can hold and, when signaled by light (photoinitiatied), will generate pharmaceutical compounds that can cleave DNA, such as in a tumor cell. “The challenge has been that tissue blocks light so we can’t signal molecules deep within the body to deliver drug therapy,” says Brewer, associate professor of chemistry.

Matthew Mongelli of Maywood N.J., a postdoctoral associate in chemistry, and his colleagues in chemistry and biology at Virginia Tech, have been working with Theralase Technologies Inc. to design molecular systems that use light that is in the therapeutic window. Starting with a complex with known DNA cleaving qualities, they changed the light absorber unit to one that responds to the red wavelength.

“Investigations into polyazine supermolecular complexes containing Ru and Os with Rh centers that possess photoactive MMCT states: Visible light induced, oxygen independent DNA photocleavage (INOR 329),” will be presented by Mongelli during the general poster session, 7 to 9 p.m., Sunday, March 13, in Convention Center Hall D. The poster has also been selected for the Sci_Mix session 7 to 9 p.m. Monday, March 14, in the Convention Center’s Sails Pavilion.

Co-authors are Brewer; undergraduate chemistry students Matthew Jeletic of Centreville, Va. and Jerita Dubash of Ashburn, Va.; and Biology Professor Brenda S. J. Winkel, all of Virginia Tech.

Brewer will also give an oral presentation on designing photochemical molecular devices and applications in photodynamic therapy and in solar energy conversion. Because of the detail offered by Mongelli’s poster, Brewer says she will focus on the exciting potential of creating molecules to reduce water to hydrogen. The talk, “Designing photochemical molecular devices utilizing Os and Ru polyazine light absorbers and Rh and Pt reactive sites: Applications in solar energy conversion and photodynamic therapy (INOR 410),” will be presented at 4:50 p.m. Monday, March 14, in Convention Center Room 4. Co-authors are chemistry Ph.D. students Mark Elvington of Blacksburg, Va. and Ran Miao of Zhangzhou City, China, Mongelli, Dubash, Jeletic, and chemistry undergraduate Julie Heinecke of Powhatan, Va.