Sensitive and direct detection using rupture event scanning (REVS/spl trade/)

Abstract

We have developed a sensitive and economical method to directly detect particles. The technique, which we term rupture event scanning (REVS/spl trade/), is based on rapidly oscillating a surface to which a particle has been attached. The oscillation can be achieved with an acoustic wave device, such as a quartz resonator, coated with particle-specific receptors. As the magnitude of oscillation of the surface is increased, there is increasing acceleration of adherent particles. This in turn results in a larger force exerted by the surface on the particle that ultimately causes rupture of the bonds attaching the particle to the surface. Using the same device, we can very sensitively monitor the excitation of vibrations in the piezoelectric substrate produced by bond rupture, which are converted into an electrical signal. The signal indicates not only the presence of specifically bound particles and their affinity for the receptor, but also the number of particles present. The method works in air, water and complex biological fluids, is quantitative over at least six orders of magnitude of particle titer, and in affinity from sub-mM to pM. For selected particle-receptor systems the sensitivity can be as low as a few fg/mm/sup 2/ (10/sup -15/ g/mm/sup 2/). The entire assay currently takes less than one hour to perform.