Proteins may be the most important and varied biomolecules within living systems. These strings of amino acids, assuming complex three-dimensional forms, are essential for the growth and maintenance of tissue, the initiation of thousands of biochemical reactions, and protecting the body from pathogens through the immune system.
“The method we report in this study uses normal cover glass instead of gold-coated cover glass, which has two advantages over our previously reported label-free, single-protein imaging method,” Wang says.
Previous methods commonly label the biomolecules of interest with fluorescent tags known as fluorophores, to better image them.
Instead, the method exploits subtle irregularities in the surface of the cover glass to produce images of razor-sharp contrast.
The use of evanescent wave scattering allows samples, including proteins, to be probed at extremely shallow depth, typically less than 100 microns.
The researchers also used ESM to keenly observe conformational changes in DNA, further demonstrating the power and versatility of the new method.