26 June 2006
Scientists Fuse Spider Silk And Silica To Create Novel New Material
by Kate Melville
Bioengineers at Tufts University, who have been delving into silk's secrets for more than a decade, have created a new fusion protein that combines the toughness of spider-silk with the intricate structure of silica. Research leader David L. Kaplan, said the resulting nanocomposite could be used in medical and industrial applications, such as growing bone tissue. "This is a novel genetic engineering strategy to design and develop new 'chimeric' materials by combining two of nature's most remarkable materials - spider silk and diatom glassy skeletons that normally are not found together," he added.
Writing in the Proceedings of the National Academy of Sciences, Kaplan describes how silica provides structural support to diatoms (single-celled organisms known for their remarkable nanostructural details) while silk proteins from spiders and silkworms are more flexible, stronger and able to self-assemble into readily defined structures. The researchers were able to design and clone genetic fusions of the encoding genes for these two proteins, and then generate these genetically engineered proteins into nanocomposites at ambient temperatures. This in itself is something of a breakthrough, as very high temperatures are usually required for the synthesis of silica in the laboratory.
More impressive is the size of the spider silk-silica composite. While past tests using silica have formed silica particles with a diameter between 0.5 and 10 nanometers, the silk-glass composite has a diameter size distribution between 0.5 and 2 nanometers. Kaplan says the smaller, more uniform size will provide better control and more options for processing, delivering "important benefits for biomedical and specialty materials."
According to Kaplan, the new chimeric protein could lead to a variety of biomedical materials that restore tissue structure and function, including bone repair and regeneration. Other applications may include areas of materials science and engineering.
Source: Tufts University