Naoya Ogata

Thin-film lasers based on dye-deoxyribonucleic acid-lipid complexes

Amplified spontaneous emission (laser action without cavities) from deoxyribonucleic acid (DNA) derivative films was achieved by doping with a hemicyanine dye which is well known as a nonlinear optical molecule. The amplification confirmed by spectral narrowing and superlinear dependence of the emission intensity on the pumping was observed from the complex films when the film samples were irradiated with a nanosecond laser at the intensity above a threshold value (∼20 μJ). The durability and low threshold values suggest the possibility of DNA complexes as a practical candidate for thin-film dye lasers.

DNA Photonics [Deoxyribonucleic Acid]

ABSTRACT Purified deoxyribonucleic acid (DNA) derived from salmon and scallop sperm has demonstrated excellent passive and active optical properties. Characterization of the optical and electromagnetic properties of DNA suggests suitability for photonic applications. One of interesting features of DNA we discovered was an intercalation of aromatic compounds into stacked layers within the double helix of DNA molecules. We found that various optical dyes inserted into the double helix of DNA molecules rendered active optical waveguide materials with excellent nonlinear optical properties. Our research included the investigation of DNA for use as an optical waveguide material as well as intercalation of fluorescent dyes, photochromic dyes, nonlinear optic chromophores, two photon dyes and rare earth compounds into DNA for use as a nonlinear optical material.

Optical and optoelectronic materials derived from biopolymer deoxyribonucleic acid (DNA)

Some of cyanine dyes and ionic functional chromophore have been widely used to probe the conformation of DNA helix through measurement of induced circular dichroism (CD) spectrum, change of UV-visible spectrum and enhancement of fluorescence. In order to develop new type optical and optoelectric materials we studied the interaction between a hemicyamnine dye and DNA in aqueous solution and have prepared the NLO dye-DNA complex films. We first found that binding of the famous NLO dyes, C22HEMI to DNA induced strong CD band in the absorption spectra of the dyes in DNA aqueous solution and DNA-CTMA complex film1. The enhancement of the fluorescence quantum yield upon binding of the dye to DNA in aqueous solution is above 100-fold. Luminescence of the hemicyanine dyes-doped in DNA-CTMA film displayed enhancement fluorescence above three orders. Refractive indices and film thickness of the self-assembled thin film determined by using the prism coupling method revealed that the self-assembled DNA thin film has anisotropic structure in two-dimensional and the self- assembled DNA-CTMA thin film is isotropic. The functional dye-DNA-CTMA film may be used to fabrication of optical waveguide, and optoelectronic devices based on the strong flurorescence, and tunable optical properties.

Deoxyribonucleic acid (DNA) cladding layers for nonlinear-optic-polymer-based electro-optic devices

Nonlinear optic (NLO) polymer based electro-optic devices have been achieving world record low half wave voltages and high frequencies over the last 2-3 years. Part of the advancement is through the use of relatively more conductive polymers for the cladding layers. Based on the current materials available for these cladding materials, however, the desired optical and electromagnetic properites are being balanced for materials processability. One does not want the solvent present in one layer to dissovle the one deposited underneath, or be dissolved by the one being deposited on top. Optimized polymer cladding materials, to further enhance device performance, are continuing to be investigated. Thin films of deoxyribonucleic acid (DNA), derived from salmon sperm, show promise in providing both the desired optical and magnetic properties, as well as the desired resistance to various solvents used for NLO polymer device fabrication. Thin films of DNA were deposited on glass and silicon substrates and the film quality, optical and electromagnetic properties and resistance to various solvents were characterized.

Light amplification in dye-doped DNA-surfactant complex films

We observed amplified spontaneous emission (laser action without cavities) from several kinds of dyes doped in films of salmon DNA (deoxyribonucleic acid) derivatives. We employed laser dye Rhodamine-6G, Pyrromethene 556, and nonlinear optical dye DMASDPB for dopants. Most of sample films with several micrometers thickness were prepared as follows: 1) DNA aqueous solution was mixed with hexadecyltrimethylammonium chloride aqueous solution. 2) precipitated DNA-lipid complex and dyes were dissolved in ethanol or chloroform. 3) Films were formed on substrates by casting from the solution. The amplified spontaneous emission was observed when the films were pumped with a nanosecond laser of 532 nm at the intensity above a threshold value. Spectral narrowing occurred at the threshold energy, and it was accompanied with superlinear dependence of the emission intensity on the pumping intensity. Dye molecules in DNA films can be intercalated in the double helix structure. Because molecules are separated form one another, it is possible to increase chromophore concentration without fluorescence quenching due to aggregation. Furthermore, it is known that DNA shows a good conducting property. We will discuss the possibility of optical and electronic devices utilizing these characteristics.

Nonlinear optical materials derived from biopolymer (DNA)-surfactant azo dye complex

This paper reports on optical and optoelectronic properties of DNA-surfactant complex films which were intercalated with a NLO dye, Disperse Red 13(DR-13). Circular dichroism (CD) analysis indicated that the orientation of the azo dye, DR-13 doped in DNA-surfactant complex film was achieved by inserting the dye molecules into the nano-size space between base pairs of DNA. The Disperse Red 13-doped DNA thin film displayed higher THG than that of CS2 about two orders. On the other hand, SHG signal could not be observed even in the presence of anisotropic ordering of the molecular chromospheres on template of the double helix of DNA, perhaps because of absorption of the dye for SHG light.

Electroluminescence as a probe for electrical and optical properties of deoxyribonucleic acid

Several class of dyes doped in deoxyribonucleic acid (DNA) derived from salmon show enhancement of fluorescence due to suppression of molecular aggregation. Also, some recent studies support electric conduction in DNA strands. Combination of these properties suggests the possibility to develop organic LED devices (OLED) based on biopolymer systems. Furthermore, the electroluminescence (EL) effect can be employed as a probe for electrical and optical properties of DNA. We fabricated OLED devices based on DNA- lipid complex and dopant dyes (ethidium bromide and fluorescein). Devices are composed of hole injection layer, dye-doped DNA-lipid layer and electrodues. OLED with ethidium bromide doped DNA showed LED emission under DC bias, but the origin of the emission was tris-(8- hydroxyquinolinato)aluminum(III)(Alq3) which was employed as an electron transporter. The current-voltage characteristics of the devices show apparent rectification behavior. From these experimental results, it is confirmed that DNA transports hole current under external DC bias. When employing fluorescein as a dopant in DNA and fabricating the devices without Alq3 layer, we observed emission from the dyes incorporated in DNA. Although the origins of the emission centers in spectra are not clear, it shows that the DNA-lipid complex will be basically applicable to OLED if additional improvements are made.

Deoxyribonucleic acid (DNA)-based nonlinear optics

Highly purified deoxyribonucleic acid (DNA) was isolated from salmon and scallop sperm by an enzymatic isolation process. Characterization of the optical and electromagnetic properties of DNA suggested suitability for optical waveguide applications. One of the characteristic features of DNA we discovered was an intercalation of aromatic compounds into stacked layers within the double helix of DNA molecules. We found that various optical dyes inserted into the double helix of DNA molecules render optical waveguide films of dye-intercalated DNA suitable for active photonic devices. Our investigation includes intercalation of fluorescent dyes, photochromic dyes, nonlinear optic chromophores, two photon dyes and rare earth compounds into DNA comparing results with poly(methyl methacrylate) (PMMA) based materials.

Deoxyribonucleic acid (DNA)-based optical materials

Optical materials for waveguiding applications must possess the desired optical and electromagnetic properties for optimal device performance. Purified deoxyribonucleic acid (DNA), derived from salmon sperm, has been investigated for use as an optical waveguide material. In this paper we present the materials processing and optical and electromagnetic characterization of this purified DNA to render a high quality, low loss optical waveguide material.

Optically controlled photonic switches based on spiropyran-doped marine-biopolymer DNA-lipid complex films

Optical switching properties based on the photochromism of spiropyran-doped DNA-lipid complex films have been studied. On-off switching of the incident light under the alternate excitation of UV- and visible light showed strong dependence of the intensity of the excitation light. We have obtained the switching times of around 200-300ms, but much faster response could be expected since the proportional tendency has not been saturated yet.