A new gel could make a “vaginal condom” that would physically entrap semen and anything it contains, including sperm and viruses such as HIV.

The gel is liquid as long as it is in contact with the acidity that is normal in a vagina, but will turn solid when it encounters semen, which is slightly alkaline. Any particles wider than 50 nanometres – including sperm, HIV and other viruses such as the herpes virus and the papilloma virus, which causes cervical cancer – are trapped, so the gel could double up as both a protectant and a contraceptive.

Patrick Kiser, whose team developed the gel at the University of Utah in Salt Lake City, says that the objective is to give women in countries where HIV is rife a cheap way to protect themselves from viruses and pregnancy even if their partner is unwilling to wear a condom.

“We did it to develop technologies that can enable women to protect themselves against HIV without the approval of their partner,” says Kiser, whose team has only tested the gel in the lab so far.


By staining HIV particles with a fluorescent dye Kiser’s team were able to show that the solidified gel halted and trapped the virus.

Drug boost

Kiser says it will be about three to five years before clinical trials begin. In the meantime he hopes to make the gel more potent by impregnating it with an anti-HIV drug to kill trapped virus before the gel is washed out of the vagina.

He cautions that previous attempts at making microbicide gels to combat HIV have failed miserably. One gel even increased the risk of infection, possibly by attracting protective white blood cells which ironically then get infected by the virus.

Journal reference: Advanced Functional Materials, DOI: 10.1002/adfm.200900757