Researchers at the University of Bath, working with colleagues at the University of Newcastle, have created a technique which can keep vaccines intact at high temperatures by encasing them in silica cages. When a protein in solution is mixed with silica, silicon dioxide binds closely around the protein to match its shape and encases the protein. A major advantage of this method is that it doesn’t require freeze-drying, something that around half of all vaccines won’t survive intact. A powder of ensilicated proteins and the silica cage enveloping the protein means it can be heated to 100°C or stored at 22°C for at least six months with no loss of function.
Once the protein has been encased in silica it can be stored or transported without refrigeration before the silica coat can be removed chemically, leaving the proteins unaffected.
The discovery means that vaccines and other important medicines could be transported much more easily, cheaply and safely, especially to remote areas or places lacking infrastructure where the need is often greatest.
The teams call their method ensilication and hope it will solve the costly and often impractical need for a cold chain to protect protein-based products including vaccines, antibodies and enzymes. The research is published in the journal Scientific Reports. The research team tested the method on three proteins; one from a tetanus vaccine, horse haemoglobin and an enzyme from egg white.
Citation: Chen, Yun-Chu, Tristan Smith, Robert H. Hicks, Aswin Doekhie, Francoise Koumanov, Stephen A. Wells, Karen J. Edler, Jean Van Den Elsen, Geoffrey D. Holman, Kevin J. Marchbank, and Asel Sartbaeva. “Thermal stability, storage and release of proteins with tailored fit in silica.” Scientific Reports 7 (2017): 46568.
doi:10.1038/srep46568.
Research funding: Royal Society, The Annett Trust
Adapted from press release by the University of Bath.