OPTICAL TWEEZERS EXPERIMENTS AT NIST. Benjamin J. Davies, Building 221. Room A161, NIST, Gaithersburg, MD 20899 (301-975-4126, email: bdavies@nist.gov)

Optical tweezers have found a wide and continually growing range of applications in microbiology since their introduction 10 years ago. They use a single tightly focused laser beam to grab on to and remotely manipulate microscopic objects, localizing them to within tens of nanometers and applying easily adjustable molecular-scale forces. Here at NIST, we have concentrated on developing a new assay in which two mesoscale particles are caused to collide using two independently controlled optical tweezers (optically controlled collisions, OPTCOL). The OPTCOL assay has been applied to evaluate the effectiveness of new polymeric inhibitors in blocking the adhesion of influenza virus to erythrocytes (red blood cells)1. Inhibition constants for the most effective inhibitors could not be measured using other types of assays, but they were readily obtained using OPTCOL. The best of the inhibitors studied are the most potent ever measured. Current work with the tweezers include velocity dependent viral attachment studies, application of OPTCOL to selectin-like adhesion processes (which are important in immune response and fertilization), and chromosome trapping.

1M. Mammen et al., Chemistry and Biology 3, 757-63, (1996).