Most conventional light microscopes have a resolution of 200 nanometers – this means that imaged objects which are any closer to one another won’t be seen as separate items. A new high-tech microscope slide, however, boosts that figure to 40 nanometers.
Developed by scientists at the University of California-San Diego, the slide is coated with a “hyperbolic metamaterial” made up of nanometer-thin alternating layers of silica glass and silver.
When light passes through this coating, its wavelength is shortened, and the light gets scattered to create a speckled pattern. A sample mounted on the slide gets illuminated from numerous angles via this speckled short-wavelength light pattern, resulting in series of low-resolution images of that sample. A linked computer subsequently utilizes a reconstruction algorithm to combine those separate images, producing one composite high-resolution image.
As a result, an ordinary light microscope using one of the slides is able to image much smaller objects than was previously possible. In tests conducted so far, the slide enabled such a microscope to image individual actin protein filaments in fluorescently labeled cells, and to image microscopic fluorescent beads and quantum dots which were spaced 40 to 80 nanometers apart.
The scientists are now adapting the technology to image subcellular structures within living cells. Ordinarily, an electron microscope would be required in order to image such tiny structures – even then, it couldn’t do so in a living cell, as its samples would have to be placed within a vacuum chamber.
A paper on the research, which is being led by Prof. Zhaowei Liu, was recently published in the journal Nature Communications.