Angewandte Chemie International Edition 2009, 48, 5134–5138
Dye-doped DNA nanofibers emit white light
Contact: Gregory A. Sotzing, University of Connecticut, Storrs (USA)
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White Luminescence from Multiple-Dye-Doped Electrospun DNA Nanofibers by Fluorescence Resonance Energy Transfer
energy transport plays an important role in the development of
optoelectonic materials. The true masters of energy transfer via a
hierarchical arrangement of different molecules are the photosynthetic
mechanisms of plants. Self-organized systems of biomolecules could also
provide a starting point for effective energy transport in future
opotoelectronic devices. A team of researchers at the University of
Connecticut and the US Air Force Research Laboratory has now
successfully used the electrospinning of DNA complexes to produce
nanofibers that incorporate two different fluorescing dyes in such a way
that energy can efficiently be transferred from one dye to the other.
The color of the resulting fluorescence can be controlled by means of
the ratio of the two dyes. As reported in the journal Angewandte
Chemie, the team led by Gregory A. Sotzing was thus able to produce
nanofibers that emit pure white light—a color that is usually very
difficult to achieve in such systems.
the electrospinning process, a polymer solution is propelled through an
electrical field. This results in the formation of nanofibers that are
deposited in the form of a mat. When DNA is subjected to such a spinning
process in the presence of a surfactant and the desired fluorescence
dyes, the result is a network of DNA fibers with organized
microstructure containing a very uniform distribution of the dyes.
dyes are tuned so that they can enter into a special interaction called
fluorescence resonance energy transfer (FRET). In this process, “energy
packets” from an excited fluorescence dye (donor) are transferred to a
second fluorescence dye (acceptor) with no radiation. The intensity of
the FRET depends, among other things, on the distance between the two
dyes. The two dyes bind to different locations on the DNA, so that the
correct spatial distribution for optimal FRET can be maintained—even at
low acceptor concentrations.
irradiation with UV light, the donor absorbs the photons and emits blue
light. If acceptor molecules are present at the right distance, some of
this energy is not re-emitted; instead it is “passed on” from the donor
to the acceptor by means of the radiation-free FRET process. The excited
acceptor molecules then emit the energy as fluorescence—in orange.
Depending on the ratio of donor and acceptor concentrations, the color
of the light changes—from blue through pure white to orange. The color
can also be fine-tuned by changing the overall dye density in the
matrix. Increasing the dye loads from 1.33 to 10 % can change a “cold”
white light to a “warm” tone.