Researchers have now created a hyperlens crystal that can in theory be used to make an optical lens that views objects just 30 nanometers in size. This would allow biologists to one day watch the immune system fight a foreign invader.
With traditional light microscopes, the resolution you see is limited by the wavelength of light. This is where electron microscopes came in, allowing scientists to see objects smaller than the wavelength of light in the nanometer scale. However, this was at the cost of killing what's being imaged, due to the high vaccum, harmful levels of radiation, or the preparation techniques involved.
This newly developed lens solves both issues, letting researchers see items the size of a virus on the surface of a living cell in their natural environment.
The innovation relies on an advancement in the ability to produce an optical material used in hyperlensing, which is the use of nanoscale metamaterials to create magnified images of items on the nanoscale. The material is known as hexagonal boron nitride, which occurs naturally, and has already been used to magnify small objects. The researchers, however, have been able to dramatically increase its imaging capabilities by a factor of ten.
“Controlling and manipulating light at nanoscale dimensions is notoriously difficult and inefficient,” explains Alexander Giles, co-author of the paper published in Nature Materials, in a statement. “We have demonstrated that the inherent efficiency limitations of hyperlenses can be overcome through isotopic engineering.”
Normally, boron contains two different isotopes, which differ in weight by about 10 percent. When the element forms part of the hyperlens, this notably alters its ability to image objects, particularly in infrared. By purifying the boron so that it only contains one isotope before it then forms the hexagonal boron nitride, the researchers were able to massively improve its optical properties.
This means that, theoretically at least, a lens crafted from these pure crystals could see features as small as 30 nanometers in size. To put this into perspective, a red blood cell is 9,000 nanometers across, while viruses tend to measure between 20 and 400 nanometers.
If and when the team are able to create bigger crystals of the hexagonal boron nitride, it could genuinely revolutionize microbiology. In theory, it would allow scientists to observe in real time cellular processes, such as a virus infecting a cell or the immune system hunting down and killing antigens.