Nano-Optical Tweezer Opens Door for Single-Molecule Protein Studies
27 May 2014
The University of Victoria in Canada has developed a nano-optical tweezer allowing the analysis of individual proteins and interactions between small-molecule drugs and DNA, SPIE reports in its journal.
The new tweezer can trap and manipulate particles the size of a micron (one thousandth of a millimeter, or 0.000039 inch) using an objective lens through which a single-beam laser is directed. It uses a standard inverted microscope, equipped with a nanofabricated metal film with a double nanohole aperture.
It is the double nanohole that gives the new nano-optical tweezer superior efficiency, compared to traditional technologies, researchers say. The new approach helps generate less heat and consume less electricity thanks to the aperture, which doesn't use surface plasmon resonance like other trapping techniques.
Also, unlike other technologies using tethers - potentially disrupting molecular motion and blocking binding sites of proteins and other molecules - the nano-optical tweezer relies only on the trapped object's intrinsic light scattering.
The new tweezer is also capable of physical dielectrostriction - a process that allows it to pull apart and unfold proteins and even DNA molecules. While not usually desired, this gives researchers a new way to study protein folding and molecular dynamics in real time.
The new approach has the potential to eventually replace fluorescence imaging - although only in the long term, according to researchers. However, it has been already used in different types of single-molecule protein studies. Possible applications of nano-optical tweezers may be found in the study of heterogeneity in virus populations and the manipulation of nanoparticles.