'Nanodrop' test tubes created with a flip o...( Researchers at the National Institut...)

Researchers at the National Institute of Standards and Technology (NIST) have demonstrated a new device that creates nanodroplet test tubes for studying individual proteins under conditions that mimic the crowded confines of a living cell. By confining individual proteins in nanodroplets of water, researchers can directly observe the dynamics and structural changes of these biomolecules, says physicist Lori Goldner, a coauthor of the paper* published in Langmuir.

Researchers recently have turned their attention to the role that crowding plays in the behavior of proteins and other biomoleculesthere is not much extra space in a cell. NISTs nanodroplets can mimic the crowded environment in cells where the proteins live while providing advantages over other techniques to confine or immobilize proteins for study that may interfere with or damage the protein. This more realistic setting can help researchers study the molecular basis of disease and supply information for developing new pharmaceuticals. For example, misfolded proteins play a role in many illnesses including Type 2 diabetes, Alzheimers and Parkinsons diseases. By seeing how proteins fold in these nanodroplets, researchers may gain new insight into these ailments and may find new therapies.

The NIST nanodroplet delivery system uses tiny glass micropipettes to create tiny water droplets suspended in an oily fluid for study under a microscope. An applied pressure forces the water solution containing protein test subjects to the tip of the micropipette as it sits immersed in a small drop of oil on the microscope stage. Then, like a magician whipping a tablecloth off a table while leaving the dinnerware behind, an electronic switch causes the pipette to jerk back, leaving behind a small droplet typically less than a micrometer in diameter.

The droplet is held in place with a laser optical tweezer, and another laser is used to excite fluorescence from the molecule or molecules in
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