Enhanced fluorescence by DNA-assembled optical antennas


Metal nanoparticles that support localized plasmon resonances, like those made of silver or gold are known to enhance the spectroscopic signals of dye molecules in their vicinity. In small nanoparticles aggregates, there is a focusing of the electromagnetic field at the hot-spot in between the particles, which gives rise to much larger enhancements than single particles.

We have been creating DNA-linked gold nanoparticle dimers on glass surfaces, during our research into ultrasensitive DNA detection where the linking molecule was a target DNA we were detecting. However, the same structures are effectively gap-based optical antenna, which should significantly enhance the fluorescence of dye molecules placed in the gap.


The proposed MSc. Project includes the creation and multimodal characterization of the dye-in-a-gap-antenna assemblies. This will include SEM microscopy to characterize the dimer structures, Dark field microscopy and spectroscopy to measure the plasmon resonance absorption of the dimers, and fluorescence lifetime microscopy and spectroscopy to study the fluorescence intensity, lifetime and bleaching properties of the dye in the dimer.

The main questions we ask are:


What is the distribution of the fluorescence enhancement when measuring it on different dimers?


Is there a change in the lifetime of the fluorescence compared to the dye-labeled DNA alone? Is the change in lifetime correlates with enhancement level?


How are the emission and excitation spectra of the dyes modified by the proximity to the metal nanoparticles?

Enhancement of fluorescence from dye-labeled DNA co-aggregated with silver particles when measured in a cuvette



Contact details: Dr. Ron Gill, r.gill@utwente.nl 053-4893067, ZH168.(Nanobiophysics group)