Silk Replaces Refrigeration

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Science  10 Aug 2012:
Vol. 337, Issue 6095, pp. 624
DOI: 10.1126/science.337.6095.624-c

Both vaccines and antibiotics lessen the burden of disease—one before the fact and one after. Successful treatment often requires a “cold chain,” in which the vaccine or antibiotic must be refrigerated from production to patient. Failure to sustain the cold chain results in loss of therapeutic efficacy, but maintaining it can be expensive, especially in developing countries. Zhang et al. demonstrate the use of silk to stabilize labile vaccine compounds at ambient temperatures. Silk fibroin, the protein polymer from silkworm cocoons, can be formed into more than scarves and ties. Specifically, as a film, silk contains tiny pockets that can harbor and protect sensitive molecules. The authors tested the efficacy of silk encapsulation on live measles, mumps, and rubella (MMR) vaccines, as well as the antibiotics penicillin and tetracycline. Their results suggest that such encapsulation can protect the compounds from degradation and temperature-induced denaturation. The activity of the MMR vaccine and the two antibiotics, as assessed with in vitro tests, was even protected in temperatures up to 60°C. This surprising application for silk has the potential to reduce reliance on the cold chain, a possibility that could be especially valuable where electricity and refrigeration are hard to come by.

Proc. Natl. Acad. Sci. U.S.A. 109, 10.1073/pnas.1206210109 (2012).

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