Spectral Imaging Of Fluorescent Multi-Colored DNA Based Nano-Structures

Increasingly, DNA and RNA are being used to construct nanotechnology. Fluorescent multi-color nanoscale optical arrays can be constructed using hairpin shaped pieces of DNA coupled to small silver clusters.  The fluorescent properties of these Ag:DNAs depends greatly on the DNA sequence of the hairpin. Our goal is to create a multi-color optical array by attaching two hairpins together that emit different colors.  It is uncertain whether these structures will retain their fluorescent properties when they are attached together, so we need a way to visualize them. Looking at bulk fluorescence of the solution does not give enough information to know if the array has properly assembled, and the structures are too small to probe structurally by standard techniques. We present a method to visualize these arrays when it is possible to immobilize them. We visualize them on a microscope, and pass the light from the microscope through a tunable optical filter.  The filter only allows certain specific frequencies of light to pass through, and the allowed frequencies depend on the angle of incidence of light onto the filter.  This allows us to view a small band of wavelengths being fluorescently emitted from the molecule. This technique provides a way to image fluorescent molecules based on what colors of light they are emitting, which can tells us whether we have succeeded in making a fluorescent multi-colored DNA based optical array.