Dynamic imaging of single biomolecular interaction using flow control and TIRFM

A rapid multi-reagents switching microvalve system integrated with a total internal reflection fluorescence microscopy (TIRFM) was developed for real time imaging of a single protein behavior. The binding and dissociation process between a chaperonin GroEL and cochaperonin GroES was observed in this TIRFM microfluidic system. For single molecular imaging in this system, biotinylated GroEL (D490C) was immobilized to the glass microchannel surface through streptavidin and biotinylated BSA. A solution including 1 nM IC5-GroES was introduced for 100 ms into the observation area and then washed out with 2 mM ATP buffer solution. Fluorescence spots of IC5-GroES appeared after rapid solution switching, and disappeared several seconds later. As a result, we succeeded in detecting fluorescence signal from single molecules in TIRFM microfluidic system.