"DNA origami nanostructures provide a platform where dye molecules can be arranged with nanoscale accuracy
allowing to assemble multiple fluorophores without dye−dye aggregation. Aiming to develop a bright and sensitive ratiometric
sensor system, we systematically studied the optical properties of nanoarrays of dyes built on DNA origami platforms using a
DNA template that provides a high versatility of label choice at minimum cost. The dyes are arranged at distances, at which they
efficiently interact by Förster resonance energy transfer (FRET). To optimize array brightness, the FRET efficiencies between
the donor fluorescein (FAM) and the acceptor cyanine 3 were determined for different sizes of the array and for different
arrangements of the dye molecules within the array. By utilizing nanoarrays providing optimum FRET efficiency and brightness,
we subsequently designed a ratiometric pH nanosensor using coumarin 343 as a pH-inert FRET donor and FAM as a pHresponsive
acceptor. Our results indicate that the sensitivity of a ratiometric sensor can be improved simply by arranging the
dyes into a well-defined array. The dyes used here can be easily replaced by other analyte-responsive dyes, demonstrating the
huge potential of DNA nanotechnology for light harvesting, signal enhancement, and sensing schemes in life sciences."