Silk Proteins in Vaccinations – Manufacture, Ship, Use. Hold The Ice!

A large number of life-saving pharmaceuticals such as MMR, penicillin, and tetracycline rely on temperature control from the manufacturing site through utilization at the delivery location in order to maintain their effectiveness. In the developing world where storage facilities may be limited this is an obvious challenge, but even in industrialized nations, pharmaceuticals and/or drug/device combination products that require temperature regulation could also benefit from a room temperature cocoon.

Researchers at Tufts University have demonstrated that silk protein (made from silkworm cocoons) can be used to stabilize some vaccines and antibiotics at temperatures above 43C for months and possibly multiple years. Additionally, this new method of vaccination preservation would aid in different storage methods such as microneedles and films.

Some details on the technology from the announcement:

Protein function depends on chains of amino acids folding into specific shapes. At higher temperatures or in the presence of water, the chains tend to unfold, then clump together, which renders them inactive. Silk fibroin is composed of interlocked crystalline sheets with numerous tiny hydrophobic pockets. The pockets trap and immobilize bioactive biomolecules — keeping them from unfolding — and also protect them from moisture. The end result is like enveloping a fragile material in a nanoscale Bubble Wrap.

Two examples: MMR and Tetracycline. Tuft’s researches showed that 85% of the MMR vaccine could retain its potency after 6 months of storage in freeze-dried silk films between 37C and 45C. For Tetracycline, an antibiotic, no activity loss was recorded for samples stored in silk films at body temperature compared to 80% for samples stored in solution. Similarly, samples stored in silk films lost only 10% activity after two weeks when held at 60C compared to 100% for samples stored in solution.

Tufts press release: New Silk Technology Preserves Heat-Sensitive Drugs for Months without Refrigeration…

Study abstract in Proceedings of the National Academy of Sciences: Stabilization of vaccines and antibiotics in silk and eliminating the cold chain