Silk and Vaccines - Who Would Have Thought?

When one thinks of a vaccine, the last thought that comes to mind is how it will be stored. Although this may seem like a minor problem, it actually is a big deal when transporting vaccines to developing countries that have little refrigeration storage.

The idea of creating a vaccine that could withstand diverse climates with little upkeep has been on the minds of researchers at Tufts University for a long time. Scientists at Tufts have reported that by using silk one can keep vaccines from degrading in hot countries where there is no refrigeration.

Over the years silk has been found to have very interesting and diverse properties. For example, silk proteins are strong, resistant to moisture, stable at extreme temperature and are biocompatible. This is demonstrated in the many applications they have been used  for- from the creation of the "bullet-proof" vest, to being used in wall coverings, to clothing and bedding. 

So why is silk so effective in preserving a vaccine? Well, David L. Kaplan and colleagues say that the silks proteins trap itself between the beta-sheets of the viral particles. This causes viral proteins to be held in their native, folded state and thus preventing denaturation. Furthermore, the structure of silk also excludes some water; enhancing its preservative qualities.

A film developed at Tufts University demonstrating silks optical properties and potential use as holographic materials. Photo: Courtesy of Fiorenzo Omenetto
Source: http://tuftsjournal.tufts.edu/2008/09/features/04/

Silk has incredible optical properties. Dr. Kaplan suggests that a sensor could be included in the vaccine to show doctors whether or not it is still fresh.

The silk protein used in the vaccine is in the form of a liquid. It is able to be a liquid because it is dissolved in a salt solution. Once this is mixed with measles, mumps and rubella it is then dried and made into films. Note that measles is one of the leading killers of children worldwide. However, after six months of storage in freeze-dried silk films at body temperature (37 C) and at 45 C/ 113 F, all components of the vaccine retained approximately 85% of their initial potency.



Tufts engineers develop a new way to stabilize vaccines and other heat-sensitive drugs using silk protein.
Source: http://now.tufts.edu/news-releases/new-silk-technology-preserves-heat-sensitive-

So how is all this possible? The research at Tufts is supported by a grant from the National Institute of Biomedical Imaging and Bioengineering at the National Institutes of Health. Overall, it builds on a significant body of work previously published by Tufts biomedical engineers seeking to tap the potential of silk for a wide range of applications.