| Nanometer-sized metal and semiconductor particles exhibit properties unique from the bulk. The properties of these particles lend themselves to potentially valuable applications in molecular-scale electronics, sensors, and catalysis. Another frontier at the nanoscale is the biological-nanoparticle interface. We have undertaken several investigations of this rich and relatively unexplored interface. The first involves the detection of unusual disease-related DNA structures by differential quenching of fluorescence of cadmium sulfide nanoparticles by DNA. In the next, the sensing properties of nanometer-sized silver particles are exploited by surface-enhanced Raman spectroscopy (SERS). This technique amplifies the molecular vibrational Raman signature when the molecule of interest is adsorbed to the silver particle. Here, damaged DNA (thymine dimers) are distinguished from “normal” DNA. In addition, a surfactantless silver wire synthetic method was developed in an attempt to exploit the “lightning rod” effect of SERS. This theoretical effect is believed to further enhance Raman signals. Gold rods have been synthesized and linked using the vitamin biotin and the protein streptavidin. Preliminary results seem to indicate a preference for end-to-end binding of these gold rods by this method. Finally, the contributing factors behind the mechanism of biological component-mediated growth of gold nanoparticles with nanoscale surface roughness are being studied. Overall, the biological-nano interface is rich with possibilities for sensing and structure on the nanoscale. |
