Increased intensities of YOYO-1-labeled DNA oligomers near silver particles

Abstract

DNA detection is usually performed using fluorescence probes. Using a DNA oligomer stained with the widely used dye 1,1'-[1,3-propanediylbis[(dimethylimino)-3,1-propanediyl]]bis[4-[(3-methyl-2(3H)-benzoxazolylidene)methyl]]-quinolinum tetraiodide (YOYO-1), we show that a substrate containing silver particles can lead to a greater than 10-fold increase in the fluorescence intensity. Proximity to silver particles also increases the photostability of YOYO-1-DNA. These results suggest that substrates or gels containing silver particles may be used for increased sensitivity in DNA detection.

Figure 1

Emission spectra of the DNA oligomers labeled with increasing concentrations of YOYO-1. The inserts show the anisotropies and intensities with increasing concentrations of YOYO-1.

Figure 2

Absorption spectra of an SIF and emission spectra of the protein-coated surfaces treated with YOYO-1 but without DNA.

Figure 3

Emission spectra of YOYO-1–labeled DNA bound to the quartz (Q) and silver (S) surfaces. The upper panels show a real-color photograph of labeled DNA spotted on the silver (left) and quartz (right) surfaces.

Figure 4

FD (top) and reconstructed time-domain (bottom) intensity decays of YOYO-1–DNA on quartz (Q) and silver (S).

Figure 5

Photostabilities of YOYO-1–DNA on quartz and silver with the same incident power (top) and at the same incident power but normalized at time zero (bottom).

Scheme 1

Schematic of surface, sequence of the DNA oligomers, structures of YOYO-1 and biotinylated oligonucleotide and experimental geometry. Note that sizes in the surface schematic are not in scale. The BSA–avidin protein layer is about 80 Å thick, and the silver particles are about 400 Å high.