Abstract

Metallic nanostructures designed to provide plasmon resonances at specific optical frequencies and strong yet uniform near-field electromagnetic enhancements are useful nanodevices for light-driven sensing and actuation. The large local fields on the surface of these structures support surface-enhanced spectroscopies such as surface enhanced Raman spectroscopy (SERS). To use plasmonic nanostructures for molecular recognition, their properties must be exploited in combination with molecular layers that provide an optical signature that corresponds to capture of a target molecule. DNA oligomers bound to the surface of plasmonic nanostructures provide an optical signal that is sensitive to the conformational changes in the DNA itself due to interaction with other molecules, as would occur in binding events. This type of optical detection is label-free and reporter-free, that is, it does not depend upon the presence of a dye molecule bound to the DNA to provide an optical signal. DNA-drug interactions can be directly detected in this manner: the binding kinetics of chemotherapy drugs such as cisplatin can be directly monitored by this method, providing a streamlined spectroscopic approach to drug discovery.

© 2009 IEEE