Crosslinking reactions of DNA film by UV irradiation were investigated in terms of structural changes
which indicated the formation of -O-P-O- bond. The UV-cured DNA films were applied to medical uses
for cell culture and wound-healing of skin, which were very effective for medical applications.
This paper describes preparations of innovative photonic devices based on high purity DNA molecules which
are obtained from Salmon roe. DNA molecules have characteristic features of double helical chain structures
where aromatic compounds can intercalate into the stacked layers so that various optically active aromatic dyes
indicate strong enhancement effects of photonic activities. Thus, various DNA photonic devices have been
developed in the world in terms of optical switches, electro-luminescence (EL), lasers and so on. However, these
DNA photonic devices adsorb moisture in the air because of hydrophilic character of DNA molecules, leading to
decrease photonic activities. Nevertheless, it was found by my group that a novel hybridization method of the
dye-intercalated DNA molecules by means of so-called so-gel process increased stabilities and durability of DNA
photonic devices under environmental changes. Also, hybridization of dye-intercalated DNA devices with synthetic
polymers including fluorinated poly(methylmethacrylate ) or polycarbonates was successfully carried out by
solution blending method, followed by casting the solution to obtain these films which showed stability and
durability increases of these DNA photonic devices.
DNA-lipid complexes showed a very strong fluorescence amplification by chelating with rare earth metals such
as Europium or Telbiumu compounds. This paper also describes the chelate effects of rare earth metal compounds
for light amplifications.
Recent research results on DNA-lipid complexes have shown various attractive features on E/O or O/E devices, optical
memories, switches and sensors by intercalating optical dye into DNA double helix. DNA devices absorbed water
under high humidity which led to decreases of optical functions. However, it is possible to improve the stability of DNA
devices by encapsulating the DNA-lipid complexes into sol-gel materials or synthetic polymers so that water permeation
is prevented by glass or synthetic polymers to stabilize and to keep the optical functions for a long time. This research
aims at stability improvements of the DNA photon devices by sealing the DNA devices either by sol-gel glass or polymer
DNA-CTMA solutions in ethanol doped by various azobenzene compounds were prepared and their absorbance transition by irradiate UV were measured. It was found that trans-cis transition took place in the cases of doped azobenzene and azobenzene-4,4'-dicarboxylic acid diethyl ester(ADCDE). It did not depend for the speed of <i>trans-cis</i> transition of solution which doped both azobenzene and ADCDE to DNA-CTMA with those amount of doping. To the next DNA-CTMA films doped by azobenzene and ADCDE were prepared and their absorbance transition by irradiate UV were measured. Consequently, <i>trans-cis</i> transition took place only by only the films doped azobenzene and was not transferred by the films doped ADCDE. It was found that <i>trans-cis</i> transition of DNA-CTMA films doped by azobenzene (100:1) was faster than PMMA films doped same amount of azobenzene. It is considered that because azobenzene molecules were isolated by intercalation to DNA and the spatial flexibility of azobenzene molecules became large, the speed of <i>trans-cis</i> transition of azobenzene became early compared with the case where it doped to PMMA.
Various DNA-cationic lipid complexes and their bulk films were prepared and their physical properties were measured. Consequently, it was found that physical properties were greatly dependent on each lipids. The DNA-lipid complexes film formed by C-12 lipid of single-chain trimethylammonium type showed largest value on mechanical strength. Water absorption behaviors of the films were also dependent on kinds of lipids. It was found that fluorescence quantum yields of cyanine doped DNA-lipid films decreased nonlinearly with increasing relative humidity, while the fluorescence quantum yields were high compared with that of PMMA in whole range of relative humidity.