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Scientists have created a gel that could prevent the transmission of HIV by physically stopping the virus in its tracks.

The 'molecular condom' was designed by scientists at the University of Utah in the United States. If it passes clinical trials, it will enable women to protect themselves against HIV without approval from their partners.

Patrick Kiser, assistant professor of bioengineering at the University of Utah, says the gel would act in a similar way to a condom. Women would insert it before intercourse and the acidic conditions of the vagina would ensure it remained liquid, allowing it to coat the vaginal walls and therefore the cells vulnerable to HIV infection.

The presence of semen makes the vagina less acidic, and it is expected that this change in pH will cause the molecules within the gel to interact and turn semisolid. The resulting mesh would be so small, virus particles would be unable to penetrate.

Unlike existing microbicides, Kiser's molecular condom appears not to be affected by high temperatures, making it potentially suitable for use in hot developing countries.

A paper describing the HIV-blocking properties of the gel was published in Advanced Functional Materials last week (10 August).

"We have shown that the gel prevents the movement of HIV," Kiser told SciDev.Net. He adds, however, that the gel's ability to trap HIV has only been shown in the laboratory and clinical trials are at least three years away.

Kiser hopes the gel will eventually work in conjunction with existing technologies. "We would want to put an antiretroviral agent in the gel, to act as another level of protection," he says.

Salim Karim, director of the Centre for the AIDS Programme of Research in South Africa (CAPRISA), says he likes the idea of a "smart" material that responds to pH.

But he adds that Kiser's team will need to demonstrate the gel's genuine effectiveness as a barrier to HIV its and ability to withstand the force applied during sex. He adds that Kiser's team may benefit from seeking advice from others with experience in microbicide research.

Karim says that if the gel proves effective against the spread of HIV in humans, it could have a substantial impact on women's ability to protect themselves against infection. This would be particularly welcome in those developing countries where women are unable to discuss preventative measures with their partners. 

Kiser aims to develop the gel into a product that remains active for 20–24 hours after a single application.

Link to abstract in Advanced Functional Materials


Advanced Functional Materials doi 10.1002/adfm.200900757 (2009)

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