Nanomaterial-Embedded DNA Films on 2D Frames

Recently, 3D printing has provided opportunities for designing complex structures with ease. These printed structures can serve as molds for complex materials such as DNA and cetyltrimethylammonium chloride (CTMA)-modified DNA that have easily tunable functionalities via the embedding of various nanomaterials such as ions, nanoparticles, fluorophores, and proteins. Herein, we develop a simple and efficient method for constructing DNA flat and curved films containing water-soluble/thermochromatic dyes and di/trivalent ions and CTMA-modified DNA films embedded with organic light-emitting molecules (OLEM) with the aid of 2D/3D frames made by a 3D printer. We study the Raman spectra, current, and resistance of Cu²⁺-doped and Tb³⁺-doped DNA films and the photoluminescence of OLEM-embedded CTMA-modified DNA films to better understand the optoelectric characteristics of the samples. Compared to pristine DNA, ion-doped DNA films show noticeable variation of Raman peak intensities, which might be due to the interaction between the ion and phosphate backbone of DNA and the intercalation of ions in DNA base pairs. As expected, ion-doped DNA films show an increase of current with an increase in bias voltage. Because of the presence of metallic ions, DNA films with embedded ions showed relatively larger current than pristine DNA. The photoluminescent emission peaks of CTMA-modified DNA films with OLEM_Red, OLEM_Green, and OLEM_Blue were obtained at the wavelengths of 610, 515, and 469 nm, respectively. Finally, CIE color coordinates produced from CTMA-modified DNA films with different OLEM color types were plotted in color space. It may be feasible to produce multilayered DNA films as well. If so, multilayered DNA films embedded with different color dyes, ions, fluorescent materials, nanoparticles, proteins, and drug molecules could be used to realize multifunctional physical devices such as energy harvesting and chemo-bio sensors in the near future.

Band gap, dielectric constant, and susceptibility of DNA layers as controlled by vanadium ion concentration

Deoxyribonucleic acid (DNA) doped with transition metal ions shows great versatility for molecular-based biosensors and bioelectronics. Methodologies for developing DNA lattices (formed by synthetic double-crossover tiles) and DNA layers (used by natural salmon) doped with vanadium ions (V3+), as well as an understanding of the physical characteristics of V3+-doped DNA nanostructures, are essential in practical applications in interdisciplinary research fields. Here, DNA lattices and layers doped with V3+ are constructed through substrate-assisted growth and drop-casting methods. In addition, enhanced physical characteristics such as the band gap energy, work function, dielectric constant, and susceptibility of V3+-doped DNA nanostructures with varying V3+ concentration ([V 3+ ]) are investigated. The critical concentration ([V 3+ ]C ) at a given amount of DNA was predicted based on an analysis of the phase transition of DNA lattices from crystalline to amorphous with specific [V 3+ ]. Generally, the [V 3+ ]C provided crucial information on the structural stability and extremum physical characteristics of V3+-doped DNA nanostructures due to the optimum incorporation of V3+ into DNA. We obtained the optical absorption spectra for energy band gap estimation; Raman spectra for identifying the preferential coordination sites of V3+ in DNA; x-ray photoelectron spectra to examine the chemical state, chemical composition, and functional groups; and ultraviolet photoelectron spectra to estimate the work function. In addition, we addressed the electrical properties (i.e. current, capacitance, dielectric constant, and storage energy) and magnetic properties (magnetic field-dependent and temperature-dependent magnetizations and susceptibility) of DNA layers in the presence of V3+. The development of biocompatible materials with specific optical, electrical, and magnetic properties is required for future applications because they must have designated functionality, high efficiency, and affordability.

The design and biomedical applications of self-assembled two-dimensional organic biomaterials

Self-assembling 2D organic biomaterials exhibit versatile abilities for structural and functional tailoring, as well as high potential for biomedical applications.

DNA nanostructures doped with lanthanide ions for highly sensitive UV photodetectors

Deoxyribonucleic acid (DNA) and lanthanide ions (Ln³⁺) exhibit exceptional optical properties that are applicable to the development of nanoscale devices and sensors. Although DNA nanostructures and Ln³⁺ ions have been investigated for use in the current state of technology for more than a few decades, researchers have yet to develop DNA and Ln³⁺ based ultra-violet (UV) photodetectors. Here, we fabricate Ln³⁺ (such as holmium (Ho³⁺), praseodymium (Pr³⁺), and ytterbium (Yb³⁺))‒doped double crossover (DX)‒DNA lattices through substrate-assisted growth and salmon DNA (SDNA) thin films via a simple drop-casting method on oxygen (O₂) plasma-treated substrates for high performance UV photodetectors. Topological (AFM), optical (UV-vis absorption and FTIR), spectroscopic (XPS), and electrical (I‒V and photovoltage) measurements of the DX‒DNA and SDNA thin films doped with various concentrations of Ln³⁺ ([Ln³⁺]) are explored. From the AFM analysis, the optimum concentrations of various Ln³⁺ ([Ln³⁺]_O) are estimated (where the phase transition of Ln³⁺‒doped DX‒DNA lattices takes place from crystalline to amorphous) as 1.2 mM for Ho³⁺, 1.5 mM for Pr³⁺, and 1.5 mM for Yb³⁺. The binding modes and chemical states are evaluated through optical and spectroscopic analysis. From UV-vis absorption studies, we found that as the [Ln³⁺] was increased, the absorption intensity decreased up to [Ln³⁺]_O, and increased above [Ln³⁺]_O. The variation in FTIR peak intensities in the nucleobase and phosphate regions, and the changes in XPS peak intensities and peak positions detected in the N 1 s and P 2p core spectra of Ln³⁺‒doped SDNA thin films clearly indicate that the Ln³⁺ ions are properly bound between the bases (through chemical intercalation) and to the phosphate backbone (through electrostatic interactions) of the DNA molecules. Finally, the I‒V characteristics and time-dependent photovoltage of Ln³⁺‒doped SDNA thin films are measured both in the dark and under UV LED illuminations (λ_LED = 382 nm) at various illumination powers. The photocurrent and photovoltage of Ln³⁺‒doped SDNA thin films are enhanced up to the [Ln³⁺]_O compared to pristine SDNA due to the charge carriers generated from both SDNA and Ln³⁺ ions upon the absorption of light. From our observations, the photovoltages as function of illumination power suggest higher responsivities, and the photovoltages as function of time are almost constant which indicates the stability and retention characteristics of the Ln³⁺‒doped SDNA thin films. Hence, our method which provides an efficient doping of Ln³⁺ into the SDNA with a simple fabrication process might be useful in the development of high-performance optoelectronic devices and sensors.