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 OLEMRed, OLEMGreen, and OLEMBlue 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.

Ternary representation of N (N = 1 or 2)-input and 1-output algorithmic self-assembly demonstrated by DNA.

Deoxyribonucleic acid (DNA) is effective for molecular computation because of its high energy efficiency, high information density, and parallel-computing capability. Although logic implementation using DNA molecules is well established in binary systems (base value of 2) via decoration of hairpin structures on DNA duplexes, systems with base values of >2 (e.g. 3, corresponding to a ternary system) are rarely discussed owing to the complexity of the design and the experimental difficulties with DNA. In this study, DNA rule tiles that participate to form algorithmic DNA crystals exhibiting the ternary representation of an N (N = 1 or 2)-input and 1-output algorithmic assembly are conceived. The number of possible algorithmic patterns is [Formula: see text] in the ternary N-input and 1-output logic gate. Thus, the number of possible rules is 27 (=33) for a 1-input and 1-output algorithmic logic gate and 19 638 (=39) for a 2-input and 1-output algorithmic logic gate. Ternary bit information (i.e. 0-, 1-, and 2-bit) is encoded on rule tiles without hairpins and with short and long hairpins. We construct converged, line-like, alternating, and commutative patterns by implementing specific rules (TR00, TR05, TR07, and TR15, respectively) for the 1-input and 1-output gate and an ascending line-like pattern (with the rule of TR3785) for the 2-input and 1-output gate. Specific patterns generated on ternary-representing rule-embedded algorithmic DNA crystals are visualized via atomic force microscopy, and the errors during the growth of the crystals are analyzed (average error rates obtained for all experimental data are <4%). Our method can easily be extended to a system having base values of >3.

Metal and Lanthanide Ion-Co-doped Synthetic and Salmon DNA Thin Films.

Researchers have begun to use DNA molecules as an efficient template for arrangement of multiple functionalized nanomaterials for specific target applications. In this research, we demonstrated a simple process to co-dope synthetic DNA nanostructures (by a substrate-assisted growth method) and natural salmon DNA thin films (by a drop-casting method) with divalent metal ions (M2+, e.g., Co2+ and Cu2+) and trivalent lanthanide ions (Ln3+, e.g., Tb3+ and Eu3+). To identify the relationship among the DNA and dopant ions, DNA nanostructures were constructed while varying the Ln3+ concentration ([Ln3+]) at a fixed [M2+] with ion combinations of Co2+-Tb3+, Co2+-Eu3+, Cu2+-Tb3+, and Cu2+-Eu3+. Accordingly, we were able to estimate the critical [Ln3+] (named the optimum [Ln3+], [Ln3+]O) at a given [M2+] in the DNA nanostructures that corresponds to the phase change of the DNA nanostructures from crystalline to amorphous. The phase of the DNA nanostructures stayed crystalline up to [Tb3+]O ≡ 0.4 mM and [Eu3+]O ≡ 0.4 mM for Co2+ ([Tb3+]O ≡ 0.6 mM and [Eu3+]O ≡ 0.6 mM for Cu2+) and then changed to amorphous above 0.4 mM (0.6 mM). Consequently, phase diagrams of the four combinations of dopant ion pairs were created by analyzing the DNA lattice phases at given [M2+] and [Ln3+]. Interestingly, we observed extrema values of the measured physical quantities of DNA thin films near [Ln3+]O, where the maximum current, photoluminescence peak intensity, and minimum absorbance were obtained. M2+- and Ln3+-multidoped DNA nanostructures and DNA thin films may be utilized in the development of useful optoelectronic devices or sensors because of enhancement and contribution of multiple functionalities provided by M2+ and Ln3+.

White light emission produced by CTMA-DNA nanolayers embedded with a mixture of organic light-emitting molecules.

Researchers have started to recognize that biomaterial-based devices and sensors can be used in the development of high-performing environmentally-friendly technologies. In this regard, DNA can be utilized as a competent scaffold for hosting functional nanomaterials to develop a designated platform in the field of bionanotechnology. Here, we introduce a novel methodology to construct CTMA-modified DNA nanolayers (CDNA NLs) embedded with single (e.g., red, green, and blue), double (violet, yellow, and orange), and triple (white) iridium-based organic light-emitting materials (OLEMs, including Ir(piq)2(acac) for red, Ir(ppy)2(acac) for green, FIrpic for blue) that can serve as active light-emitting layers. The OLEM-embedded CDNA NLs were fabricated using simple solution processes, and their spectral properties were investigated via Fourier-transform infrared (FTIR), X-ray photoelectron (XPS), UV-Vis, and photoluminescence (PL) spectroscopies. FTIR analysis of OLEM-embedded CDNA NLs suggested that the complexes are stable and chemically inert. XPS revealed the various modes of interaction between OLEMs and CDNA. The evidence of interactions between blue OLEM and CDNA was demonstrated by peak shifts. The wide band gap characteristics (∼4.76 eV) and relatively high optical quality (no absorption in the visible region) of OLEM-embedded CDNA NLs were observed in UV-Vis absorption measurements. We observed PL emission in OLEM-embedded CDNA NLs, which was caused by the energy transfer from CDNA to OLEMs (ligand-centered and metal to ligand charge transfer). Lastly, a white light-emitting OLEM-embedded CDNA thin film was constructed using a combination of appropriate concentrations of red, green, and blue OLEMs. Its characteristic was demonstrated through spectral measurements. In addition, colour coordinates were plotted in the International Commission on Illumination (CIE) colour space, which confirmed the colour identity for the developed colours (including white). Consequently, the OLEM-embedded CDNA NLs can likely be used as a functional material in bio-imaging and bio-photonics.

DNA Multilayers with Mono-, Hetero-, and Mixed-Type Plasmonic Nanoparticles for Broadband Absorption and Energy Storage.

DNA incorporated with functional materials has led to development of hybrids with different functionalities. Among the functional materials, metal nanoparticles such as Au, Ag, and Cu (also known as plasmonic nanoparticles [PNPs]), which can exhibit surface plasmon resonance, are good candidates to fabricate useful optoelectronic devices and sensors. Here, we constructed PNP-assorted DNA (PNP-DNA) layers with mono-, hetero-, and mixed-type PNPs formed by successive spin-coating to obtain the required number of layers. Further, structural analysis of PNP-DNA was performed by scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The optical evaluation was carried out by Raman, UV-visible, and photoluminescence (PL) spectroscopies followed by measurement of capacitance. Cross-sectional SEM images of DNA single, DNA triple, and PNP-DNA triple layers indicated their thicknesses (i.e., 90, 280, and 395 nm, respectively), while the base pair distance of double helixes (∼0.4 nm) for the PNP-DNA multilayers was measured by XRD. The presence of Ag, Au, and Cu PNPs was confirmed by existence of spin-orbit coupling in the corresponding XPS spectra. The addition of PNPs in DNA multilayers caused significant enhancement in the intensities of Raman bands (especially in the range of 1200-1850 cm-1) due to Raman resonance. UV-vis absorption and PL demonstrated stacking-order-dependent and layer-dependent light absorption and energy transfer (observed as quenching of fluorescence between PNPs and DNA), respectively. We observed n-type semiconducting behavior with a relatively higher dielectric constant for a PNP-assorted DNA single layer at a low frequency of 5 kHz. The dielectric constants of all samples decreased exponentially with increased frequency. Upon addition of PNPs, enhancement in the dielectric constant as well as capacitance was noted. Consequently, the simple fabrication method used in this study can be adopted to construct various nanomaterial-assorted DNA multilayers whose specific functionalities may be controlled with high efficiency.

Phase, current, absorbance, and photoluminescence of double and triple metal ion-doped synthetic and salmon DNA thin films.

We fabricated synthetic double-crossover (DX) DNA lattices and natural salmon DNA (SDNA) thin films, doped with 3 combinations of double divalent metal ions (M2+)-doped groups (Co2+-Ni2+, Cu2+-Co2+, and Cu2+-Ni2+) and single combination of a triple M2+-doped group (Cu2+-Ni2+-Co2+) at various concentrations of M2+ ([M2+]). We evaluated the optimum concentration of M2+ ([M2+]O) (the phase of M2+-doped DX DNA lattices changed from crystalline (up to ([M2+]O) to amorphous (above [M2+]O)) and measured the current, absorbance, and photoluminescent characteristics of multiple M2+-doped SDNA thin films. Phase transitions (visualized in phase diagrams theoretically as well as experimentally) from crystalline to amorphous for double (Co2+-Ni2+, Cu2+-Co2+, and Cu2+-Ni2+) and triple (Cu2+-Ni2+-Co2+) dopings occurred between 0.8 mM and 1.0 mM of Ni2+ at a fixed 0.5 mM of Co2+, between 0.6 mM and 0.8 mM of Co2+ at a fixed 3.0 mM of Cu2+, between 0.6 mM and 0.8 mM of Ni2+ at a fixed 3.0 mM of Cu2+, and between 0.6 mM and 0.8 mM of Co2+ at fixed 2.0 mM of Cu2+ and 0.8 mM of Ni2+, respectively. The overall behavior of the current and photoluminescence showed increments as increasing [M2+] up to [M2+]O, then decrements with further increasing [M2+]. On the other hand, absorbance at 260 nm showed the opposite behavior. Multiple M2+-doped DNA thin films can be used in specific devices and sensors with enhanced optoelectric characteristics and tunable multi-functionalities.

Morphological and Optoelectronic Characteristics of Double and Triple Lanthanide Ion-Doped DNA Thin Films.

Double and triple lanthanide ion (Ln(3+))-doped synthetic double crossover (DX) DNA lattices and natural salmon DNA (SDNA) thin films are fabricated by the substrate assisted growth and drop-casting methods on given substrates. We employed three combinations of double Ln(3+)-dopant pairs (Tb(3+)-Tm(3+), Tb(3+)-Eu(3+), and Tm(3+)-Eu(3+)) and a triple Ln(3+)-dopant pair (Tb(3+)-Tm(3+)-Eu(3+)) with different types of Ln(3+), (i.e., Tb(3+) chosen for green emission, Tm(3+) for blue, and Eu(3+) for red), as well as various concentrations of Ln(3+) for enhancement of specific functionalities. We estimate the optimum concentration of Ln(3+) ([Ln(3+)]O) wherein the phase transition of Ln(3+)-doped DX DNA lattices occurs from crystalline to amorphous. The phase change of DX DNA lattices at [Ln(3+)]O and a phase diagram controlled by combinations of [Ln(3+)] were verified by atomic force microscope measurement. We also developed a theoretical method to obtain a phase diagram by identifying a simple relationship between [Ln(3+)] and [Ln(3+)]O that in practice was found to be in agreement with experimental results. Finally, we address significance of physical characteristics-current for evaluating [Ln(3+)]O, absorption for understanding the modes of Ln(3+) binding, and photoluminescence for studying energy transfer mechanisms-of double and triple Ln(3+)-doped SDNA thin films. Current and photoluminescence in the visible region increased as the varying [Ln(3+)] increased up to a certain [Ln(3+)]O, then decreased with further increases in [Ln(3+)]. In contrast, the absorbance peak intensity at 260 nm showed the opposite trend, as compared with current and photoluminescence behaviors as a function of varying [Ln(3+)]. A DNA thin film with varying combinations of [Ln(3+)] might provide immense potential for the development of efficient devices or sensors with increasingly complex functionality.