Chemists seek light-activated glue for vascular repair

03/23/04

Surgeons battle time and the body's defenses as they stitch together veins and arteries, whether after an injury or in the course of such treatments as transplants or bypasses. Loss of blood before a site is closed and too much clotting soon after challenge medical care.

Virginia Tech researchers are creating biocompatible adhesives for use with vascular tissue that will speed the process of mending tissue. They will present the research at the 227th annual meeting of the American Chemical Society in Anaheim, Calif., March 28 through April 1, 2004.

The goal is to make it possible for surgeons to splice, reattach, or mend vascular tissue by applying a biopolymer coating and activating it with light, such as a laser, explains Timothy Long of Blacksburg, professor of chemistry in the College of Science at Virginia Tech. Another use would be as a stable, easy-to-use material that medics could apply to stop bleeding and prevent clotting.

Chemistry doctoral student Afia S. Karikari will explain the structure and characteristics of the novel polymer, how light causes it to change shape and function, and what the researchers have determined about the properties of several compounds that are candidates for a material that could make laser assisted vascular repair possible.

Karikari, a Packard Fellow, is a graduate of Clark Atlanta University. A native of Ghana, West Africa, she moved to the United States with her family and attended Pebblebrook High School in Mableton, Ga.

She will present the paper, "Photocrosslinking of star-shaped poly(d,l-lactide)s containing an ethoxylate core (Poly 368)" at 8:50 a.m. Tuesday, March 30, 2004, in the Garden B room of the Anaheim Coast Hotel. Co-authors are Craig Thatcher, professor and department head of large animal clinical sciences in the Virginia–Maryland Regional College of Veterinary Medicine, and Long.

Abstract:
Star-shaped poly(d,l-lactide)s (poly(DLLA)s) containing an ethoxylate core and functionalized with acrylate and methacrylate pendant groups are presented as ideal bioadhesives. The polymerization of DLLA using pentaerythritol ethoxylate and Sn(Oct)2 was controlled. Narrow molecular weight distributions (1.07-1.13) were obtained. High degree of substitutions of 90% was obtained when the hydroxy-terminated 4-arm stars were functionalized with acryloyl chloride and methacrylic anhydride to obtain acrylate and methacrylate pendant groups. Photocrosslinking of the modified stars resulted in networks with an average gel content of 99%. The thermal properties of the stars and the photocrosslinked poly(DLLA)s were determined using differential scanning calorimetry. Significant increases in the glass transition temperatures were observed after photocrosslinking. The functionalized oligomers were shown to be promising candidates for laser assisted vascular repair.

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