Being able to detect viruses in fluid, such as a drop of blood, would be a clinical microbiologist’s dream. Currently expensive and time-consuming cell culture assays are used. A nanobiotechnologist working from the Centre for Research on Adaptive Nanostructures and Nanodevices (CRANN) in Dublin, has developed a practical method using vibrating micro-cantilevers to detect viruses. As the viruses float by, they stick to cell proteins that are attached to the cantilevers. This causes them to vibrate, which can then be detected.
More from the article in Nature:
Microcantilevers — which look like springboards but are only 0.5 millimetres long and just 1 micrometer thick — wobble and bend in response to different forces. By measuring changes in the frequencies at which these tiny planks vibrate, researchers have, for example, turned them into super-sensitive virus-weighing scales.
But these biosensors have some limitations. Cell membrane proteins that bind to viruses are difficult to attach to the cantilevers and easily lose their activity when they’re removed from cells. And because liquids dampen frequency changes, most measurements have been made in air, if not in a vacuum, rather than in physiological conditions.
… To ensure that FhuA — an Escherichia coli membrane protein that is known to bind to the T5 virus — didn’t lose its activity, Hegner and his colleagues reconstituted it in sheets of membrane-like vesicles, then sprayed the vesicles onto selected cantilevers in an array using inkjet technology, similar to that found in printers. They were also able to overcome the dampening effects of the fluid by measuring changes in high frequency vibrations, which are more sensitive to small changes in mass.
When the array was submerged in a T5-containing fluid, the researchers detected the virus binding to FhuA by measuring shifts in the vibrational frequency of the cantilevers. The study appears in Nature Nanotechnology.
Read the article here…
Flashback: 3-D Virus Imaging wth Magnetic Resonance Force Microscopy
Image: Microcantilevers used in the study (Martin Hegner)
