Fluorescent nanoparticles that can be attached to biological molecules are being developed for use in microscopic sensor devices. Philip Costanzo, a graduate student in chemistry at UC Davis, and Timothy Patten, associate professor of chemistry, have prepared nanoparticles of cadmium sulphide and silicon dioxide coated with polymer chains with biotin attached to the ends. When avidin, a protein that binds to biotin, is added, the nanoparticles cluster into larger aggregates. The researchers used dynamic light scattering, electron microscopy and other methods to study these aggregates.
These nanoparticles could be used both to fluorescently label biological molecules and as a means to transport them in an electric field, Patten said. A proposed device would use microscopic needles to take up very small volumes of tissue fluid through the skin, mix it with nanoparticles designed to detect particular molecules, and move them to another part of the device for detection.