Deoxyribonucleic Acid Films Research Articles

Deoxyribonucleic Acid‐Based Electron Selective Contact for Crystalline Silicon Solar Cells

AbstractDevelopment of carrier selective contacts for crystalline silicon solar cells has been recently of great interest toward the further expansion of silicon photovoltaics. The use of new electron and hole selective layers has opened an array of possibilities due to the low‐cost processing and non‐doping contacts. Here, a non‐doped heterojunction silicon solar cell without the use of any intrinsic amorphous silicon is fabricated using Deoxyribonucleic acid (DNA) as the electron transport layer (ETL) and transition metal oxide V2O5 as the hole transport layer (HTL). The deposition and characterization of the DNA films on crystalline silicon have been studied, the films have shown a n‐type behavior with a work function of 3.42 eV and a contact resistance of 28 mΩ cm2. This non‐doped architecture has demonstrated a power conversion efficiency of 15.6%, which supposes an increase of more than 9% with respect to the cell not containing the biomolecule, thus paving the way for a future role of nucleic acids as ETLs.

Investigation of third order nonlinearity of Ethidium bromide doped deoxyribonucleic acid) DNA)

The concentrations-dependent refractive index n 2 and the nonlinear absorption coefficient β of Ethidium bromide dye-doped deoxyribonucleic acid (biological polymer DNA) solutions in the SDL regime at 532 nm are reported. The Z-scan technique was performed in two ways and two different wavelengths, 532nm and 473nm, the open aperture technique and the closed aperture technique. From open aperture Z-scan measurements it is found that the Ethidium bromide doped deoxyribonucleic acid films exhibited reverse saturable absorption. The coefficient of nonlinear refraction and nonlinear absorption coefficient at 473nm wavelength is greater than at 532nm.

Redox Mechanism of Azathioprine and Its Interaction with DNA.

The electrochemical behavior and the interaction of the immunosuppressive drug azathioprine (AZA) with deoxyribonucleic acid (DNA) were investigated using voltammetric techniques, mass spectrometry (MS), and scanning electron microscopy (SEM). The redox mechanism of AZA on glassy carbon (GC) was investigated using cyclic and differential pulse (DP) voltammetry. It was proven that the electroactive center of AZA is the nitro group and its reduction mechanism is a diffusion-controlled process, which occurs in consecutive steps with formation of electroactive products and involves the transfer of electrons and protons. A redox mechanism was proposed and the interaction of AZA with DNA was also investigated. Morphological characterization of the DNA film on the electrode surface before and after interaction with AZA was performed using scanning electron microscopy. An electrochemical DNA biosensor was employed to study the interactions between AZA and DNA with different concentrations, incubation times, and applied potential values. It was shown that the reduction of AZA molecules bound to the DNA layer induces structural changes of the DNA double strands and oxidative damage, which were recognized through the occurrence of the 8-oxo-deoxyguanosine oxidation peak. Mass spectrometry investigation of the DNA film before and after interaction with AZA also demonstrated the formation of AZA adducts with purine bases.

Chroma-hue controllable color and thermocolor-added deoxyribonucleic acid films

Deoxyribonucleic acid (DNA) is a useful scaffolding material for the alignment of nanomaterials with specific functionalities. Here, we fabricated multi-layered (e.g., single, triple, and quintuple) color-added DNA films with a different color in each layer on substrates as well as a self-supported film with a mixture of different colors. A color-added DNA thin film on a substrate was prepared by either drop-casting or spin-coating, and a self-supporting DNA film was constructed by an oven-drying procedure. The optical characteristics of DNA films with various color dye concentrations were studied through transmittance and absorption. In addition, color profiles (i.e., chroma and hue angle) of the self-supporting DNA films were investigated by considering reflectance to obtain International Commission on Illumination LAB (CIELAB) values (where L, A, and B represent the brightness, x-axis (green-red), and y-axis (yellow-blue) in the CIE color space, respectively). Color profiles were obtained by L, A, and B. The chroma of the self-supporting DNA film with more colors were relatively small, indicating a dark achromatic characteristic of the samples. The hue angle of each film corresponded to the characteristic colors. Finally, the reversibility of the color change of DNA films embedded with thermochromatic dyes was demonstrated by varying the temperature to verify use in practical applications.

Mechanical Stabilization of Deoxyribonucleic Acid Solid Films Based on Hydrated Ionic Liquid.

Solid films of deoxyribonucleic acid (DNA) containing a hydrated ionic liquid, choline dihydrogen phosphate (CDP), were prepared by a solvent-casting method. Thermal properties, aggregation structure, thermal molecular motion, and tensile properties of CDP-containing DNA films were examined by thermogravimetry (TG), wide-angle X-ray diffraction (WAXD) measurement, dynamic mechanical analysis (DMA), and tensile tests, respectively. The water retentivity of the films at room temperature was much improved with CDP. The packing density of DNA helical chains clearly depended on the amount of CDP in the film. A small amount of CDP contributed to the suppression of the BI → BII conformational transition and the cooperative motion of the DNA duplex in the film. The tensile properties of the film drastically changed in the presence of CDP. When the amount of hydrated CDP in the film increased, the mechanical response of the film changed from glassy-like to rubbery-like via a semicrystalline-like state. The above results make it clear that CDP plays two major roles as a water absorber and plasticizer in the DNA film. Thus, it can be concluded that the use of an ionic liquid as an additive significantly increases the possibility of using a DNA solid film as a structural material.

Uracil-doped DNA thin solid films: a new way to control optical dispersion of DNA film using a RNA constituent.

Among five nucleobases, adenine (A), guanine (G), cytosine (C), thymine (T) and uracil (U), uracil is a key distinctive constituent existing only in ribonucleic acid (RNA). RNA shares the common A, G, and C with deoxyribonucleic acid (DNA) made of A-T, G-C hydrogen bonding. We explored a new attempt to combine uracil (U) with DNA, successfully realizing U-doped DNA thin solid films for the first time. Impacts of uracil on optical properties of the films were thoroughly investigated. The method was based on optimal spin-coating of an aqueous solution of DNA and uracil over silicon or silica substrates. Optical absorption of both aqueous solution and U-doped DNA thin solid films was characterized in a wide spectral range covering UV-visible-IR. Immobilization of uracil within DNA thin solid films was experimentally confirmed by FTIR spectroscopy studies. By using an ellipsometer, we measured the refractive indices of the films and discovered that U-doping was a very effective means to control optical dispersion DNA thin solid film. We further investigated thermo-optic behavior to find impacts of U-doping in DNA films. Detailed thin film processes and optical characterizations are discussed.

Method of assembling pure Langmuir–Blodgett DNA films using TBE buffer as the subphase

The advantage of using Langmuir–Blodgett (LB) method in assembling thin films refers mainly to the effective deposition of mono- and multilayer films with an organized, well-defined molecular orientation and ordered layer structure. Deoxyribonucleic acid (DNA), in recent times, has also been deposited using LB technique to form films on solid substrates for various studies. However, it has been quite a challenge for researchers to obtain pure homogenous DNA film due to the hydrophilic nature of DNA that makes it unable to float on water subphase. In this work, an unconventional approach was employed by suspending synthetic DNA molecules on a subphase of Tris base, Boric acid with ethylenediamine tetra acetic acid (EDTA) (TBE) buffer instead of deionized water. Spectroscopic, morphological, and electrical characterisations were then carried out for further understanding of the resulting DNA film on solid substrates. The obtained results confirmed DNA layer functionality with uniform film formation, which demonstrated a strong rectification when electrical studies were conducted. For this purpose, we employed the LB-derived pure DNA films integrated within a metal–semiconductor or Schottky junction, confirming previous reports on semiconductor-like behaviour of DNA molecules. We believe, the possibility of obtaining pure DNA film using the LB method may allow in-depth investigations pertaining to DNA interaction with various other macromolecules besides exciting applications in various electronic devices, especially in the field of biosensors.

Optoelectrical and mechanical properties of multiwall carbon nanotube-integrated DNA thin films

Thin films made of deoxyribonucleic acid (DNA), dissolved in an aqueous solution, and cetyltrimethyl-ammonium-modified DNA (CDNA), dissolved in an organic solvent, utilising multiwall carbon nanotubes (MWCNTs) are not yet well-understood for use in optoelectronic device and sensor applications. In this study, we fabricate MWCNT-integrated DNA and CDNA thin films using the drop-casting method. We also characterise the optical properties (i.e. absorption spectra, Fourier-transform infrared spectra, Raman spectra, photoluminescence, and time-of-flight secondary ion mass spectrometry) to study spectral absorption, interaction, functional group, chirality, and compositional moiety and its distribution of MWCNTs in DNA and CDNA thin films. The electrical property for conductance and the mechanical characterisations of hardness, modulus and elasticity for stability are also discussed. Lastly, to show the feasibility of directional alignment of MWCNTs in DNA thin films, we perform an alignment experiment with MWCNTs in DNA via brushing and shearing methods, and we evaluate the results using polarised optical microscopy. Our simple methodology to align ingredients in DNA and CDNA thin films leveraging various optical, electrical and mechanical properties, provides great potential for the development of efficient devices and sensors.

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 (λLED = 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.

Optical dispersion control in surfactant-free DNA thin films by vitamin B2 doping

A new route to systematically control the optical dispersion properties of surfactant-free deoxyribonucleic acid (DNA) thin solid films was developed by doping them with vitamin B2, also known as riboflavin. Surfactant-free DNA solid films of high optical quality were successfully deposited on various types of substrates by spin coating of aqueous solutions without additional chemical processes, with thicknesses ranging from 18 to 100 nm. Optical properties of the DNA films were investigated by measuring UV-visible-NIR transmission, and their refractive indices were measured using variable-angle spectroscopic ellipsometry. By doping DNA solid films with riboflavin, the refractive index was consistently increased with an index difference Δn ≥ 0.015 in the spectral range from 500 to 900 nm, which is sufficiently large to make an all-DNA optical waveguide. Detailed correlation between the optical dispersion and riboflavin concentration was experimentally investigated and thermo-optic coefficients of the DNA-riboflavin thin solid films were also experimentally measured in the temperature range from 20 to 85 °C, opening the potential to new bio-thermal sensing applications.

Biologically active nanocomposite of DNA-PbS nanoparticles: A new material for non-volatile memory devices

Composite films of deoxyribonucleic acid (DNA) and lead sulfide (PbS) nanoparticles are prepared to fabricate biological memory devices. A simple solution based electrografting is developed to deposit large (few cm2) uniform films of DNA:PbS on conducting substrates. The films are studied by X-ray photoelectron spectroscopy, field emission SEM, FTIR and optical spectroscopy to understand their properties. Charge transport measurements are carried out on ITO-DNA:PbS-metal junctions by cyclic voltage scans, electrical bi-stability is observed with ON/OFF ratio more than ∼104 times with good stability and endurance, such performance being rarely reported. The observed results are interpreted in the light of strong electrostatic binding of nanoparticles and DNA stands, which leads doping of Pb atoms into DNA. As a result, these devices exhibit negative differential resistance (NDR) effect due to oxidation of doped metal atoms. These composites can be the potential materials in the development of new generation non-volatile memory devices.

Thermal stability of the solid DNA as a novel optical material

Deoxyribonucleic acid (DNA) has been extensively exploited for the past decade as the matrix material in organic electronics and nonlinear optics. In this work thermal stability of DNA in solid form was thoroughly studied, mainly by optical methods. Solid samples of low molecular mass DNA were subjected to heating according to different protocols and dissolved. The temperature effect was observed in the evolution of UV absorption and circular dichroism spectra. Thin films of DNA were deposited on polished silicon wafers. They were conditioned at consecutively raised temperature and simultaneously measured by spectroscopic ellipsometry. Changes in chemical composition of thermally treated films were studied by XPS. Below 100 °C all thermal effects were reversible. Melting occurred at c.a.140 °C. Irreversible chemical changes probably occurred at 170–180 °C.

Ultrafast nonlinear optical properties of thin-solid DNA film and their application as a saturable absorber in femtosecond mode-locked fiber laser

A new extraordinary application of deoxyribonucleic acid (DNA) thin-solid-film was experimentally explored in the field of ultrafast nonlinear photonics. Optical transmission was investigated in both linear and nonlinear regimes for two types of DNA thin-solid-films made from DNA in aqueous solution and DNA-cetyltrimethylammonium chloride (CTMA) in an organic solvent. Z-scan measurements revealed a high third-order nonlinearity with n2 exceeding 10−9 at a wavelength of 1570 nm, for a nonlinarity about five orders of magnitude larger than that of silica. We also demonstrated ultrafast saturable absorption (SA) with a modulation depth of 0.43%. DNA thin solid films were successfully deposited on a side-polished optical fiber, providing an efficient evanescent wave interaction. We built an organic-inorganic hybrid all-fiber ring laser using DNA film as an ultrafast SA and using Erbium-doped fiber as an efficient optical gain medium. Stable transform-limited femtosecond soliton pulses were generated with full width half maxima of 417 fs for DNA and 323 fs for DNA-CTMA thin-solid-film SAs. The average output power was 4.20 mW for DNA and 5.46 mW for DNA-CTMA. Detailed conditions for DNA solid film preparation, dispersion control in the laser cavity and subsequent characteristics of soliton pulses are discussed, to confirm unique nonlinear optical applications of DNA thin-solid-film.

Use of a DNA film on a self-assembled monolayer for investigating the physical process of DNA damage induced by core electron ionization

Purpose: A novel two-layer sample composed of a deoxyribonucleic acid (DNA) film and self-assembled monolayer (SAM) was prepared on an inorganic surface to mimic the processes in which DNA is damaged by soft X-ray irradiation.Materials and methods: A mercaptopropyltrimethoxysilane (MPTS) SAM was formed on a sapphire surface, then oligonucleotide (OGN) molecules were adsorbed on the MPTS-SAM. The thicknesses and chemical states of the layers were determined by X-ray photoelectron spectroscopy (XPS) and near-edge X-ray fine structure (NEXAFS) around the phosphorus (P) and sulfur (S) K-edges. To induce the damage to the OGN molecules, the sample was irradiated with synchrotron soft X-rays. The chemical state of the OGN molecules before and after irradiation was examined by NEXAFS around the nitrogen (N) K-edge region.Results: The thickness of the MPTS-OGN layer was approximately 7.7 nm. The S atom of the OGN molecules was located at the bottom of the OGN layer. The peak shape of the N K-edge NEXAFS spectra of the MPTS-OGN layers clearly changed following irradiation.Conclusions: The MPTS-OGN layer formed on the sapphire surface. The chemical states and the structure of the interface were elucidated using synchrotron soft X-rays. The OGN molecules adsorbed on the MPTS films decomposed upon exposure to soft X-ray irradiation.

DNA-based nanocomposite biocoatings for fire-retarding polyurethane foam

Layer-by-layer (LbL)-assembled multilayer thin films of deoxyribonucleic acid (DNA), chitosan (CHI) and montmorillonite (MMT) were studied in an effort to produce fully renewable, bio-based, fire-retardant coatings for flexible polyurethane foam. The polyurethane foam (PUF) biocoatings constructed of ten bilayers (BLs) of CHI/DNA+MMT (16·2 % mass), ten trilayers of CHI/MMT/DNA (8·1 % mass) and five quadlayers of CHI/DNA/CHI/MMT (4·9 % mass) all resulted in a significant reduction in critical flammability metrics, peak heat release rate (pHRR) and average HRR (aHRR). The mix BL, CHI/DNA+MMT, is the best formulation as it resulted in the greatest flammability reduction (51% pHRR and 81% aHRR) with the fastest biocoating growth and the least amount of preparation and waste. This DNA- and MMT-based biocoating is the greatest flammability reduction of PUF reported to date using the LbL process. Constructed of bio-based and non-toxic materials combined with the fast-growing BL approach, which has minimal waste, this is presumably the most environmental and bio-friendly fire-retardant LbL coating on flexible polyurethane foam reported. This article contains supporting information that will be made available online once the issue is published.

Green solid films with tunable mechanical properties made from deoxyribonucleic acid

Promoting green innovation to establish a worldwide low-carbon society is an urgent priority. Effective utilization of natural resources excluding fossil fuels is one of the efforts that will contribute to the resolution of this issue. Here, we show that solid-state films made from deoxyribonucleic acid (DNA) can be used as a structural material. The great advantage of the DNA films over the ones made from synthetic polymers is that the mechanical properties are controllable, from glassy to rubbery, via semicrystalline by simply regulating the water content in the film. Why and how such unique mechanical properties can be manifested by the DNA films is determined from detail structural analyses using Fourier-transform infrared spectroscopy and wide-angle X-ray diffraction measurements. With an increasing water content, the conformation of double-stranded DNA (dsDNA) was changed from the A-form in an amorphous state to the B-form in a partially packed one. dsDNA in the B-form became densely packed as the film was stretched. Solid-state films made from deoxyribonucleic acid where the mechanical properties are controllable, from glassy to rubbery, via semicrystalline by simply regulating the water content in the film. In recent years, DNA has proven to be a versatile material not only for applications in biomedicine but also – further from its natural function – as a reliable building block in materials engineering. Yet, little is known about its properties in the solid state. Hisao Matsuno, Keiji Tanaka and co-workers have now shown that DNA films make for structural materials with mechanical properties that can be tuned simply by varying the amount of water they contain. Drier films behave like glassy polymers; on wetting, the films become semi-crystalline and then rubber-like. By characterizing the films through infrared spectroscopy and X-ray diffraction, the Japan-based team revealed that the tensile response arises from a structural change: with little water, the DNA double helices adopt the compact, right-handed A-form. With increasing water content, these convert to the more well-known B-form. Furthermore, they pack more densely under stretching.

DNA – novel nanomaterial for applications in photonics and in electronics

Abstract Functionalization with surfactants and with active molecules of deoxyribonucleic acid (DNA), thin film processing as well as their nonlinear optical and electrical properties are reviewed and discussed. On the basis of a quantum three level model, we show that the anomalous concentration variation of cubic susceptibility χ ( 3 ) ( − 3 ω ; ω , ω , ω ) in thin films of DNA–CTMA complexes doped with Disperse Red 1 chromophore can be explained by the concentration variation of two-photon resonance contribution. We show also that the DNA complexes, plasticized with glycerol and adequately doped can be processed into self standing conducting membranes with a high electrical conductivity. The measured ionic conductivity at room temperature, depending on dopant used and its concentration, is in the range of 3.5 × 10 − 4 – 10 − 5 S / cm and increases linearly as a function of temperature, reaching 10 − 3 S / cm at 358 K for the most conducting sample, obeying predominantly the Arrhenius law. Practical applications of DNA complexes are also described and discussed.

Characterization of flexible DNA films

Polymer electrolytes (PEs) are currently the focus of much attention as potential electrolytes in electrochemical devices such as batteries, display devices and sensors. Deoxyribonucleic acid (DNA) as an important biological macromolecule has electric conducting electrochemical properties and unique three dimensional structures. With the goal of developing a new family of environmentally friendly multifunctional biohybrid materials displaying simultaneously high ionic conductivity we have produced in the present work, flexible films based on DNA, incorporating ionic liquids (ILs). Over the last decade ILs have been employed as a new media in electrochemistry and electroanalysis.The materials studied here have been characterized by means of Differential Scanning Calorimetry, Complex Impedance Spectroscopy and Cyclic Voltammetry.

Optical Properties of Thin Films of DNA-CTMA and DNA-CTMA Doped with Nile Blue

Refractive index dispersion of thin films of deoxyribonucleic acid (DNA)-surfactant (CTMA) and doped DNA-CTMA-Nile Blue (NB) (5 w%) complexes are reported and discussed. The thermal variation of the thin film thickness was measured by ellipsometry. The DNA-CTMA complex exhibits a rarely observed negative thermal expansion between room temperature and ca. 85°C. Doping with NB decreases the temperature range of negative thermal expansion to between room temperature and ca. 70°C. The dopping by 5 w% of NB lowers the absolute value of negative thermal expansion of DNA-CTMA system from 5% to 2% within this temperature range.

Formation of Complex Langmuir and Langmuir-Blodgett Films of DNA with a Dichain Cationic Surfactant

Formation of complex monolayers between a dichain cationic surfactant, namely, dihexadecyldimethylammonium bromide (DHDAB) and deoxyribonucleic acid (DNA) at the air-water interface was first time systematically investigated here. The adsorption of DNA onto DHDAB monolayer was monitored by observing the surface pressure vs. time graph. The polyion-complex monolayers formed in situ through the electrostatic attraction between cationic DHDAB and the phosphate groups of anionic DNA. The organization of the DNA-DHDAB complex at the air-water interface deduced from surface pressure-area (π-A) isotherms was compared with the spectroscopic data in Langmuir-Blodgett films. Study of UV-Vis absorption spectra of pure DNA solution and DNA adsorbed DHDAB complex Langmuir-Blodgett films confirms the successful transfer of the films onto quartz substrates.