DNA-surfactant complexes:preparation, self-assembly properties and applications in synthesis and bioelectronics

The powerful ionic self-assembly behavior of DNA-surfactant complexes make it a unique material for various applications from optoelectronics to biomedicine. Three types of DNA-surfactant assemblies, including bulk films, lyotropic liquid crystals (LCs) and hydrogels have been investigated extensively. Aside from these achievements, here, DNA-surfactant thermotropic LCs has been developed. Lamellar structures of the DNA-surfactant complexes are formed. It was found that the phase transition temperatures of DNA-surfactant complexes can be controlled over a wide temperature range. In particular, we found a new class of modulated smectic LC phase, which exhibits an additional periodicity perpendicular to the layer normal, i.e. an in-plane layer undulation. Furthermore, we report a novel phase-dependent electrochromic device by directly injecting the DNA-surfactant complex in a LC cell. In the liquid crystal isotropic phase, electric field-induced coloration and bleaching have a switching time of seconds. Upon transition to the smectic LC phase, a remarkable optical memory of the written state is observed without color decay for many hours in the absence of applied voltage. Thereby, the volatility of optoelectronic state can be controlled simply by changing the phase of the material. Additionally, the complexation of DNA with surfactants can also be used as a chemically reactive scaffold for the fabrication of amphiphilic oligonucleotides in organic phase. Therefore, the results presented in this thesis are crucial for the further development of several fields where nucleic acids play an important role like DNA nanotechnology, chemical biology and bioelectronics