It begins as a liquid.
When it comes into contact with the surfaces it is designed to protect, it congeals to form a thin, protective layer of solid gel.
And when its targeted intruder is present, it instantly changes back into a liquid, simultaneously delivering a lethal dose of antiviral chemicals.
It sounds like science fiction, but researchers at the University of Utah are working to bring this new type of "molecular condom" into reality.
"The words 'molecular condom,' put together, really mean microbicide," said lead researcher Patrick Kiser, an assistant professor of bioengineering at the university.
Microbicides, chemicals applied to the vaginal area in order to protect against HIV, have been in development for nearly two decades.
Researchers are experimenting with a host of different forms, from chemical-laced rings to antiviral gels.
What makes this microbicide different is that it is activated by the very substance that potentially carried the HIV virus -- semen.
"We are using the potential disease-carrying agent -- in other words, the semen -- to trigger the release of the drug with the hopes that this would make the microbicide much more active," Kiser said.
"We're targeting the virus before it can interact with the woman's tissues."
Women using the gel would apply it to the vaginal area before sex.
Once exposed to the higher temperature of vaginal tissues, the polymer-based gel would solidify, forming a protective barrier that would coat vulnerable tissues.
In the presence of semen, which is less acidic than the normal conditions inside the vagina, the solid gel would melt, delivering a burst of anti-HIV chemicals.
In addition to offering targeted protection, the solid gel form could ideally allow a single application of the microbicide to last for days or weeks.
Currently, the research is focused on developing a gel that would only fight HIV infection, it would not prevent pregnancy.
However, Kiser says if the anti-HIV version one day proves successful, other applications could also be forthcoming.
"We haven't designed this as a contraceptive; however, it would be possible to put a contraceptive into the gel," he said. "It is really a medium for a drug."
The Utah molecular condom, if developed, could give women an additional option in protecting themselves against HIV and AIDS. The gel may prove particularly useful in some African cultures in which condom use is not highly accepted.
"This is an important new prevention strategy for women globally," said Michael Relf, chair of the department of nursing at Georgetown University.
"Strategies that allow women to individually reduce their risk for HIV is breakthrough because it removes the barriers of partner negotiation related to condom use. This could have significant impact on the incidence of HIV, both for woman and their future children," Relf said.
Technology Is Years Away
Those waiting for this novel new method of protection shouldn't hold their breath.
Kiser says five years to 10 years of additional research and trials will be needed to ensure safety and efficacy.
"Taking a slick idea from the lab and turning it into a useful drug or device is fraught with peril, as the project can fail at any point," said Dr. Judith Feinberg, a professor of medicine at the University of Cincinnati.
She says any one of a number of possible pitfalls could hinder the use of this microbicide -- from toxicity to an unacceptable taste or consistency.
Above all others, though, the question of effectiveness is perhaps the most important.
Though more than a dozen microbicides are currently in development, not one has yet been proven to deliver the efficacy afforded by other prophylactic methods, such as condoms.
Kiser says microbicides of the future could approach the effectiveness seen with barrier contraception.
"It is imminently doable to build a microbicide that has 90-percent effectiveness," Kiser said. "That is our hope."
But many say that when dealing with a virus like HIV, it is far better to be safe than sorry.
"I, however, think we should still use with condoms when possible," said Dr. Kristin Ries, professor of internal medicine at the University of Utah. "I would not discourage condoms at all as they have shown to be very effective in prevention of HIV spread in many studies."
"We need large, controlled studies, even to be sure it is safe, then to see if [it's] effective. These will be difficult to do as ethically, as I think we must not recommend [microbicides] without condoms," Ries said.
Another Weapon in the Anti-AIDS Arsenal?
Experts still see microbicides as a potentially important tool in the fight against HIV.
"Microbicides are not going to be the ultimate solution for the HIV pandemic," Kiser said. "But I think the idea is that between this and condoms and testing and education, we can kind of cut the top off of the expansion of the pandemic and get it more under control."
"None have been approved as none have proven safe and effective yet; however, developing one would be great in the fight against HIV," Ries said. "Also, it would put the prevention in the hands of women who do not have choices in many cultures."
Feinberg says a lack of interest on the part of pharmaceutical companies is also slowing the development of microbicides. However, she says such chemicals could be useful.
"Microbicides have great potential, I think, to slow the spread of the epidemic," Feinberg said. "An option for protection against HIV and other STDs that would be under the woman's control would be significant."
"Right now women are dependent on their partners' willingness to access and use a condom, and convincing men to do this has not proven to be easy," she said.