DNA-Controlled Excitonic Switches (original) (raw)

DNA-mediated excitonic upconversion FRET switching

New Journal of Physics, 2015

Excitonics is a rapidly expanding field of nanophotonics in which the harvesting of photons, ensuing creation and transport of excitons via Förster resonant energy transfer (FRET), and subsequent charge separation or photon emission has led to the demonstration of excitonic wires, switches, Boolean logic and light harvesting antennas for many applications. FRET funnels excitons down an energy gradient resulting in energy loss with each step along the pathway. Conversely, excitonic energy upconversion via upconversion nanoparticles (UCNPs), although currently inefficient, serves as an energy ratchet to boost the exciton energy. Although FRET-based upconversion has been demonstrated, it suffers from low FRET efficiency and lacks the ability to modulate the FRET. We have engineered an upconversion FRET-based switch by combining lanthanide-doped UCNPs and fluorophores that demonstrates excitonic energy upconversion by nearly a factor of 2, an excited state donor to acceptor FRET efficiency of nearly 25%, and an acceptor fluorophore quantum efficiency that is close to unity. These findings offer a promising path for energy upconversion in nanophotonic applications including artificial light harvesting, excitonic circuits, photovoltaics, nanomedicine, and optoelectronics.

Excitonics: A Set of Gates for Molecular Exciton Processing and Signaling

ACS Nano, 2018

Regulating energy transfer pathways through materials is a central goal of nanotechnology, as a greater degree of control is crucial for developing sensing, spectroscopy, microscopy, and computing applications. Such control necessitates a toolbox of actuation methods that can direct energy transfer based on user input. Here we introduce a proposal for a molecular exciton gate, analogous to a traditional transistor, for regulating exciton flow in chromophoric systems. The gate may be activated with an input of light or an input flow of excitons. Our proposal relies on excitation migration via the second excited singlet (S 2) state of the gate molecule. It exhibits the following features, only a subset of which are present in previous exciton switching schemes: picosecond-timescale actuation, amplification/gain behavior, and a lack of molecular rearrangement. We demonstrate that the device can be used to produce 1 Page 1 of 32 ACS Paragon Plus Environment ACS Nano universal binary logic or amplification of an exciton current, providing an excitonic platform with several potential uses, including signal processing for microscopy and spectroscopy methods that implement tunable exciton flux.

A Reversible DNA Logic Gate Platform Operated by One- and Two-Photon Excitations

Angewandte Chemie (International ed. in English), 2015

We demonstrate the use of two different wavelength ranges of excitation light as inputs to remotely trigger the responses of the self-assembled DNA devices (D-OR). As an important feature of this device, the dependence of the readout fluorescent signals on the two external inputs, UV excitation for 1 min and/or near infrared irradiation (NIR) at 800 nm fs laser pulses, can mimic function of signal communication in OR logic gates. Their operations could be reset easily to its initial state. Furthermore, these DNA devices exhibit efficient cellular uptake, low cytotoxicity, and high bio-stability in different cell lines. They are considered as the first example of a photo-responsive DNA logic gate system, as well as a biocompatible, multi-wavelength excited system in response to UV and NIR. This is an important step to explore the concept of photo-responsive DNA-based systems as versatile tools in DNA computing, display devices, optical communication, and biology.

Positional characteristics of fluorophores influencing signal output of a DNA nanoswitch

2006 Bio Micro and Nanosystems Conference, 2006

The Holliday junction (HJ) structure, consisting of four DNA double helices with a central branch point, is capable of switching between conformational states upon ion binding. The HJ nanoswitch described here comprises a long, dual labeled cloverleaf oligonucleotide and a short, unlabeled oligonucleotide. Fluorescent labeling with donor and acceptor dyes placed on the HJ arms of the cloverleaf strand allows the ion induced conformational switch to be detected optically using fluorescence resonance energy transfer (FRET). The influence of donor and acceptor dye location on the detection of conformational switching has been investigated using two distinct HJ structures. In addition, the effect of increasing HJ arm length in order to increase donor and acceptor dye separation has been evaluated. We report that a preferential HJ nanoswitch structure can be determined, capable of efficient detection of ion induced conformational switching.

Excitonics: A universal set of binary gates for molecular exciton processing and signaling

2017

The ability to regulate energy transfer pathways through materials is an important goal of nanotechnology, as a greater degree of control is crucial for developing sensing, solar energy, and bioimaging applications. Such control necessitates a toolbox of actuation methods that can direct energy transfer based on user input. Here we propose a novel molecular exciton gate, analogous to a traditional transistor, for controlling exciton migration in chromophoric systems. The gate may be activated with an input of light or an input flow of excitons. Unlike previous gates and switches that control exciton transfer, our proposal does not require isomerization or molecular rearrangement, instead relying on excitation migration via the second singlet (S2) state of the gate molecule--hence the system is named an "S2 exciton gate." After presenting a set of system properties required for proper function of the S2 exciton gate, we show how one would overcome the two possible challenge...

Chemical Science Electronic control of DNA-based nanoswitches and nanodevices

Here we demonstrate that we can rationally and finely control the functionality of different DNA-based nanodevices and nanoswitches using electronic inputs. To demonstrate the versatility of our approach we have used here three different model DNA-based nanoswitches triggered by heavy metals and specific DNA sequences and a copper-responsive DNAzyme. To achieve electronic-induced control of these DNA-based nanodevices we have applied different voltage potentials at the surface of an electrode chip. The applied potential promotes an electron-transfer reaction that releases from the electrode surface a molecular input that ultimately triggers the DNA-based nanodevice. The use of electronic inputs as a way to finely activate DNA-based nanodevices appears particularly promising to expand the available toolbox in the field of DNA nanotechnology and to achieve a better hierarchical control of these platforms.

Assembling programmable FRET-based photonic networks using designer DNA scaffolds

Nature Communications, 2014

DNA demonstrates a remarkable capacity for creating designer nanostructures and devices. A growing number of these structures utilize Förster resonance energy transfer (FRET) as part of the device's functionality, readout or characterization, and, as device sophistication increases so do the concomitant FRET requirements. Here we create multi-dye FRET cascades and assess how well DNA can marshal organic dyes into nanoantennae that focus excitonic energy. We evaluate 36 increasingly complex designs including linear, bifurcated, Holliday junction, 8-arm star and dendrimers involving up to five different dyes engaging in fourconsecutive FRET steps, while systematically varying fluorophore spacing by Förster distance (R 0 ). Decreasing R 0 while augmenting cross-sectional collection area with multiple donors significantly increases terminal exciton delivery efficiency within dendrimers compared with the first linear constructs. Förster modelling confirms that best results are obtained when there are multiple interacting FRET pathways rather than independent channels by which excitons travel from initial donor(s) to final acceptor. | www.nature.com/naturecommunications AE, antenna effect; E, end-to-end efficiency. All values are collected from at least three independently assembled structures. S.d. for AE and E values from replicate experiments are all o10%. *Initial Cy3 n absorption at 550 nm relative to the final Cy5 absorption at 650 nm.

Reversible energy-transfer switching on a DNA scaffold

Journal of the American Chemical Society, 2015

We show that FRET between Pacific Blue (PB) and Alexa488 (A488) covalently attached to a DNA scaffold can be reversibly controlled by photochromic switching of a spiropyran derivative. With the spiropyran in the closed spiro isomeric form, FRET occurs freely between PB and A488. UV-induced isomerization to the open merocyanine form shuts down the FRET process by efficient quenching of the PB excited state. The process is reversed by exposure to visible light, triggering the isomerization to the spiro isomer.

Excitonic AND Logic Gates on DNA Brick Nanobreadboards

ACS Photonics, 2015

A promising application of DNA self-assembly is the fabrication of chromophore-based excitonic devices. DNA brick assembly is a compelling method for creating programmable nanobreadboards on which chromophores may be rapidly and easily repositioned to prototype new excitonic devices, optimize device operation, and induce reversible switching. Using DNA nanobreadboards, we have demonstrated each of these functions through the construction and operation of two different excitonic AND logic gates. The modularity and high chromophore density achievable via this brick-based approach provide a viable path toward developing information processing and storage systems.