Engineers here used compressed carbon dioxide (CO2) to push chemicals into a plastic that is often used as a bone replacement. With further development, the technology could be used in a wide range of plastics that release medicines -- from antibiotics to anti-tumor agents - into the body.

The high-pressure, high-temperature CO2 is neither gas nor liquid, but is known as a "supercritical fluid," explained David Tomasko, associate professor of chemical engineering at Ohio State. Supercritical fluids are often used in industry because they penetrate materials like a gas but can dissolve some substances -- such as grease -- and other chemicals like a liquid.

"Though supercritical CO2 has long been developed as a means of extracting molecules, this work shows that it can be used in the opposite way," said David Tomasko, associate professor of chemical engineering at Ohio State.

The study also revealed that engineers can control the pressure of the CO2 to alter the internal structure of the plastic and create voids that may enable the material to hold larger quantities of medicine than might normally be possible.

Tomasko and John Lannutti, associate professor of materials science and engineering, their graduate students Taryn Sproule and Hongbo Li, and undergraduate student J. Alex Lee, published their results in a recent issue of the Journal of Supercritical Fluids.

Supercritical CO2 is gaining popularity as an environmentally friendly dry-cleaning agent and textile-dyeing solvent, but it is the fluid's ability to sterilize surfaces that could prove key for making medically active implants. Currently, implants are sterilized with heat, radiation, or chemicals that can make embedded medicines less effective, Tomasko explai
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Contact: David Tomasko
Tomasko.1@osu.edu
614-292-4249
Ohio State University
23-Mar-2004