This project exploits the unique properties of magnetic nanoparticles (MNP) to develop a new type of biological assay. In the proposed assay, binding events between biological molecules and functionalized MNPs are detected by changes in the frequency-dependent magnetic relaxation signal of the MNPs. The relaxation time is determined by Brownian rotation of the particles in solution and is directly proportional to the particle volume. By appropriate selection of the particle properties, nanometer-scale changes in particle diameter can be detected. The detection method relies on a sinusoidal frequency sweep of the magnetic field and optical readout - the MNP become birefringent under an applied field, allowing highly sensitive measurements to be made with a simple optical setup and greatly facilitating later on-chip miniaturization.
Project end date: 07/31/08