Technology.am (Aug. 15, 2005) — University of Utah scientists developed a new kind of “molecular condom” to protect women from AIDS.
Before sex, women would insert a vaginal gel that turns semisolid in the presence of semen, trapping AIDS virus particles in a microscopic mesh so they can’t infect vaginal cells.
“We have created the first vaginal gel designed to prevent movement of the AIDS virus. This is unique. There’s nothing like it, “says Patrick Kiser, an associate professor of bioengineering at the University of Utah’s College of Engineering.
“We did it to develop technologies that can enable women to protect themselves against HIV without approval of their partner,” he adds.
The earlier “molecular condom” was applied as a liquid, which then turned into a gel coating at body temperate, and then turned liquid again in the presence of semen (which alters pH balance to be less acidic), thereby triggering the release of an anti-HIV drug.
The new “molecular condom” works in the opposite way, starting as a gel but becoming semi-solid in response to pH changes caused by the introduction of semen, thereby forming a nanoscopic mesh of crosslinked molecules so tightly woven that they form a serious barrier to the virus.
The new gel is applied as a gel, and then becomes more solid and impenetrable as changes in pH alter the strength of the bond between the gel’s two key components, both of which are polymers, or long, chain-like molecules made of many smaller, repeating units: PBA, or phenylboronic acid, and SHA, or salicylhydroxamic acid.
The researcher showed that the mesh of molecules–at 30 to 50 nanometers wide–should be able to block any HIV particle, which is two to three times thicker. This should also block sperm, which measure 5,000 to 10,000 nanometers (5 to 10 microns).
The study suggested that after sex the vagina gradually becomes more acidic again, and any residual HIV particles would be inactivated by not only this acidity, but also the antiviral drug within the remaining gel.
The research team is funded by the National Institutes of Health and the Bill and Melinda Gates Foundation.