Friday, 13 July 2018

Fluorescent silk kills harmful bacteria

A far-red fluorescent silk can kill harmful bacteria, as demonstrated in controlled trials. The developers see the material as both a biomedical and and an environmental remedy to combating harmful organisms and protecting patients.

The development of the new silk hybrid material (mKate2) comes from Purdue University. The material attacks bacteria when it is illuminated by a green light. The microbial-killing effect is due to the activation of a far-red fluorescent protein. The main application will be with bandages to help accelerate wound healing and to prevent infection. The aim was to come up with something safer than light-activate microbial killing technology, where organisms are killed using photocatalytic processes involving catalysts like titanium dioxide.

The material is formed from natural substrates. Here Purdue University worked with the Korean National Institute of Agricultural Research to create what are termed plasmonic photocatalyst-like biomaterials, to be used in conjunction with visible light, to kill pathogenic microbes.

While the use of silk may seem strange, according to lead researcher Professor Young Kim: "Silk is an ancient and well-known biomaterial. It doesn't have any issues with the human body. And the nice thing about green light is that it's not harmful -- the color corresponds to the strongest intensity of the solar spectrum."

To combine the benefits of silk and green light, the scientists inserted the gene for "mKate2" (which is a far-red fluorescent protein, into silk worms. By shining a green light on the hybrid generates reactive oxygen species. These are powerful radicals for breaking down organic contaminants and attacking the membrane and DNA of bacteria. In trials, significant reductions of pathogenic Escherichia coliwere seen.

The research into the material has been published in the journal Advanced Materials; the research paper is titled "Green-Light-Activated Photoreaction via Genetic Hybridization of Far-Red Fluorescent Protein and Silk."

Posted by Dr. Tim Sandle, Pharmaceutical Microbiology

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