A silica cage renders proteins stable against denaturing thermal treatment and long-term temperature storage.
A novel approach that encloses vaccinations in tiny silica cages and requires no refrigeration would make it easier and safer to transport vital medications to remote areas worldwide.
Many medications contain proteins that break down and become unusable once exposed to room temperatures. To prevent this, they are held in cold chain storage.
Unfortunately, breaks in the cold chain do occur and are considered a serious global public issue, particularly for masschildhood vaccinationprograms in developing countries. Each year, breaks in cold chain storage result in the loss of millions of doses of vaccines.
“Once the proteins in a vaccine break down and tangle up, it’s useless,” said Dr Asel Sartbaeva, lead investigator of thestudypublished inScientific Reports. “You can think of it like an egg that’s been boiled—–it can’t be unboiled.
“So, the ability to store and transport proteins at room temperatures or even hotter would remove a major logistical problem for safely delivering vaccines and other medicines to patients around the world.”
To combat this issue, investigators created a novel technique called ensilication that allows proteins to remain intact at high temperatures of up to 100°C or 212°F by incasing them in silica cages.
Once the proteins are encased in silica, they can be stored or transported without the need for refrigeration before the silica coat can be removed chemically, leaving the proteins unaffected.
“We have demonstrated with ensilication that we can simply and reliably keep proteins from breaking down even at up to 100°C, or store them as a powder for up to 3 years at room temperature without loss of function.
When a protein in solution is mixed with silica, silicon dioxide binds closely around the protein and quickly builds up layers to encase the protein. Unlike similar techniques, this method does not require freeze-drying—–a process through which approximately half of all vaccines would not survive intact.
A powder of ensilicated proteins and the silica cage enveloping the protein allow it to be heated to 100°C or stored at 22°C for at least 6 months with zero loss of function.
The method was tested on 3 proteins: from a tetanus vaccine, from horse hemoglobin, and in an enzyme from egg white.
“We’re very excited by the potential applications of ensilication and our next steps will be to test our findings on more vaccines, antibodies, antiviral and anti-venom drugs, and other biopharmaceuticals.”