A "molecular condom" to protect women against HIV is being developed by US scientists.
The liquid formulated by a University of Utah team turns into a gel-like coating when inserted into the vagina.
Then, when exposed to semen, it returns to liquid form and releases an anti-viral drug to attack HIV.
However, the technology, featured in the Journal of Pharmaceutical Sciences, is still around five years away from being tested in humans. We're shooting for a microbicide delivery system that would be used once a day or once a month Dr Patrick KiserUniversity of Utah
And the researchers predict it will be around 10 years before it might be in widespread use.
Researcher Dr Patrick Kiser said: "The ultimate hope for this technology is to protect women and their unborn or nursing children from the Aids virus."
The Utah project is part of a worldwide research effort to develop "microbicides" - drug-delivery systems such as gels, rings, sponges or creams to prevent infection by HIV and other sexually transmitted diseases.
They are seen as a way for women to gain power by protecting themselves from HIV, particularly in impoverished nations where Aids is widespread, where rape is rampant, or, where conventional condoms are taboo, not reliably available or where men resist using them.
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