Abstract

Detecting Single DNA Molecules with Optical Microcavities

Frank Vollmer, Professor, Max Planck Institute for the Science of Light

Detecting single biomolecules and their interactions is the dream of biochemists since it allows the fundamental study of biochemical reactions. Achieving biosensing capability at the single molecule level is, moreover, a particularly important goal since single molecule biosensors would not only operate at the ultimate detection limit by resolving individual molecular interactions, but they could also monitor biomolecular properties which are otherwise obscured in ensemble measurements. For example, a single molecule biosensor could resolve the fleeting interactions between a molecule and its receptor, with immediate applications in clinical diagnostics. We demonstrate single molecule biosensing with an optical microcavity biosensor platform. Using an optical microcavity and gold nanorods, we have enhanced the interaction of light with DNA to the extent that we can now track interactions between individual DNA molecules. Our approach makes it possible to use a single DNA oligonucleotide receptor and to follow its successive interactions with DNA molecules in a sample solution. Based on the duration and frequency of the measured interactions, it is then possible to detect DNA molecules, and differentiate even single nucleotide mismatches.