Spider silk creates super-resolution lens
Image: Spider silk from Nephila spider provides natural super-resolution lens [Toby Hudson]
Researchers from the UK Universities of Oxford and Bangor have used spider silk as a superlens to increase microscope resolution well beyond the classical limit.
The natural 'biosuperlens' can distinctly resolve 100 nm features under a white-light microscope, making the smallest bacteria now visible using conventional light microscopy.
"It's very exciting to find yet another cutting edge and totally novel use for a spider silk, which we have been studying for more than two decades in my laboratory," highlights Professor Fritz Vollrath from the Department of Zoology, University of Oxford.
Transparent microspheres and cylinders can function as super-resolution lenses to focus light beyond the diffraction limit but fabrication is complex and expensive.
However, in this world first, Vollrath and colleagues have used a naturally-occurring biological material as a superlens.
By applying the dragline silk from a thumb-sized golden web Nephila spider to the surface of the material to be viewed, the researchers boosted magnification by up to three times.
As Dr Zengbo Wang from Bangor University says: "Manufactured superlenses involve complex engineering processes that are not widely accessible to researchers. [But by using] a naturally occurring superlens provided by 'Mother Nature'... everyone can access superlenses."
The researchers went onto view details on a microchip and blue-ray disk that would not have been visible using an unmodified optical microscope, and reckon the set-up could be used to image biological microstructures including germs and viruses.
(a) Nephila edulis spider in its web. (b) Schematic: Spider silk was placed directly on sample surface using soft tape to magnify underlying objects 2-3 times (c) SEM image of Blu-ray disk (d) Clear magnified image (2.1x) of Blu-ray disk under spider silk superlens. [Bangor University/ University of Oxford]
"[We] distinctly resolved 100 nm features under a conventional white-light microscope with a peak wavelength of 600 nm attaining a resolution of λ/6 that is well beyond the classical limit," says Vollrath.
According to Wang, the cylindrical silk lens provides a wider field of view compared to a microsphere superlens.
As he adds: "Importantly for commercial applications, a spider silk nanoscope would be robust and economical, which could provide excellent manufacturing platforms for a wide range of applications."