Photoluminescence behaviors of organic soluble DNA bearing carbazole and pyrene derivatives as side-chain substituents and effect of the copolymer structure on the Förster energy transfer process

Magneto-optical and thermal characteristics of magnetite nanoparticle-embedded DNA and CTMA-DNA thin films

Recently, DNA molecules embedded with magnetite (Fe₃O₄) nanoparticles (MNPs) drew much attention for their wide range of potential usage. With specific intrinsic properties such as low optical loss, high transparency, large band gap, high dielectric constant, potential for molecular recognition, and their biodegradable nature, the DNA molecule can serve as an effective template or scaffold for various functionalized nanomaterials. With the aid of cetyltrimethylammonium (CTMA) surfactant, DNA can be used in organic-based applications as well as water-based ones. Here, DNA and CTMA-DNA thin films with various concentrations of MNPs fabricated by the drop-casting method have been characterized by optical absorption, refractive index, Raman, and cathodoluminescence measurements to understand the binding, dispersion, chemical identification/functional modes, and energy transfer mechanisms, respectively. In addition, magnetization was measured as a function of either applied magnetic field or temperature in field cooling and zero field cooling. Saturation magnetization and blocking temperature demonstrate the importance of MNPs in DNA and CTMA-DNA thin films. Finally, we examine the thermal stabilities of MNP-embedded DNA and CTMA-DNA thin films through thermogravimetric analysis, derivative thermogravimetry, and differential thermal analysis. The unique optical, magnetic, and thermal characteristics of MNP-embedded DNA and CTMA-DNA thin films will prove important to fields such as spintronics, biomedicine, and function-embedded sensors and devices.

DNA-surfactant complexes: self-assembly properties and applications

Over the last few years, DNA-surfactant complexes have gained traction as unique and powerful materials for potential applications ranging from optoelectronics to biomedicine because they self-assemble with outstanding flexibility spanning packing modes from ordered lamellar, hexagonal and cubic structures to disordered isotropic phases. These materials consist of a DNA backbone from which the surfactants protrude as non-covalently bound side chains. Their formation is electrostatically driven and they form bulk films, lyotropic as well as thermotropic liquid crystals and hydrogels. This structural versatility and their easy-to-tune properties render them ideal candidates for assembly in bulk films, for example granting directional conductivity along the DNA backbone, for dye dispersion minimizing fluorescence quenching allowing applications in lasing and nonlinear optics or as electron blocking and hole transporting layers, such as in LEDs or photovoltaic cells, owing to their extraordinary dielectric properties. However, they do not only act as host materials but also function as a chromophore itself. They can be employed within electrochromic DNA-surfactant liquid crystal displays exhibiting remarkable absorptivity in the visible range whose volatility can be controlled by the external temperature. Concomitantly, applications in the biological field based on DNA-surfactant bulk films, liquid crystals and hydrogels are rendered possible by their excellent gene and drug delivery capabilities. Beyond the mere exploitation of their material properties, DNA-surfactant complexes proved outstandingly useful for synthetic chemistry purposes when employed as scaffolds for DNA-templated reactions, nucleic acid modifications or polymerizations. These promising examples are by far not exhaustive but foreshadow their potential applications in yet unexplored fields. Here, we will give an insight into the peculiarities and perspectives of each material and are confident to inspire future developments and applications employing this emerging substance class.

Nanocomposite approaches for enhancing the DC and photoconductivity of DNA films

Enhanced DC conductivity and photoconductivity of cationic carbazole tethered deoxyribonucleic acid (Cz-DNA) in film devices is achieved by incorporating mobility enhancers. An anthracene-based organic semiconductor (namely 4HPA-Ant) and the inorganic semiconductor cadmium sulfide (CdS) multipod nanocrystal (NC) were used as the mobility enhancers. Space charge limited current (SCLC) experiments show that hole mobility in CdS:Cz-DNA composite film is improved significantly, by about an order of magnitude, compared to the Cz-DNA film. Similarly, the DC conductivity of the composite film is slightly enhanced by 4HPA-Ant. The photoconductivity is also improved in the Cz-DNA composite, with both 4HPA-Ant and CdS multipod NCs. The enhancement in photocurrent is by more than an order of magnitude, as demonstrated by current-voltage (I-V) characterization using DNA composite photodetectors.