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.

Large-Scale Fabrication of Copper-Ion-Coated Deoxyribonucleic Acid Hybrid Fibers by Ion Exchange and Self-Metallization.

It has been a challenge to achieve deoxyribonucleic acid (DNA) metallization and mass production with a high quality. The main aim of this study was to develop a large-scale production method of metal-ion-coated DNA hybrid fibers, which can be useful for the development of physical devices and sensors. Cetyltrimethylammonium-chloride-modified DNA molecules (CDNA) coated with metal ions through self-metallization exhibit enhanced optical and magnetic properties and thermal stability. In this paper, we present a simple synthesis route for Cu2+-coated CDNA hybrid fibers through ion exchange followed by self-metallization and analyze their structural and chemical composition (by X-ray diffraction (XRD), high-resolution field emission transmission electron microscopy (FETEM), and energy-dispersive X-ray spectroscopy (EDS)) and optical (by ultraviolet (UV)-visible absorption, Fourier transform infrared (FTIR), and X-ray photoelectron spectroscopies (XPS)), magnetic (by vibrating-sample magnetometry), and thermal (by a thermogravimetric analysis) characteristics. The XRD patterns, high-resolution FETEM images, and selected-area electron diffraction patterns confirmed the triclinic structure of Cu2+ in CDNA. The EDS results revealed the formation of Cu2+-coated CDNA fibers with a homogeneous distribution of Cu2+. The UV-vis, FTIR, and XPS spectra showed the electronic transition, interaction, and energy transfer between CDNA and Cu2+, respectively. The Cu2+-coated CDNA fibers exhibited a ferromagnetic nature owing to the presence of Cu2+. The magnetization of the Cu2+-coated CDNA fibers increased with the concentration of Cu2+ and decreased with the increase in temperature. Endothermic (absorbed heat) and exothermic (released heat) peaks in the differential thermal analysis curve were observed owing to the interaction of Cu2+ with the phosphate backbone.

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+.

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.

High performance UV photodetectors using Nd3+ and Er3+ single- and co-doped DNA thin films.

Even though lanthanide ion (Ln3+)-doped DNA nanostructures have been utilized in various applications, they are rarely employed for photovoltage generating devices because of difficulties in designing DNA-based devices that generate voltages under light illumination. Here, we constructed DNA lattices made of synthetic strands and DNA thin films extracted from salmon (SDNA) with single-doping of Nd3+ or Er3+ and co-doping of Nd3+/Er3+ for high performance UV detection. The topological change of the DNA double-crossover (DX) lattices during the course of annealing was estimated from atomic force microscope (AFM) images to find the optimum concentration of Ln3+ ([Ln3+]O). No topological disturbance in DNA DX lattices were observed up to [Ln3+]O, and significant enhancement in the physical properties was obtained at [Ln3+]O. The interactions between Ln3+ and SDNA were examined using spectroscopic methods of UV-visible, Raman, and X-ray photoelectron spectroscopy (XPS). Current and photovoltage measurements for Ln3+-doped SDNA thin films under UV illumination with varying power intensities were conducted. Under UV illumination, the photocurrent and photovoltage of Ln3+-doped SDNA thin films increased with increasing applied external voltages and input power intensities, respectively. In addition, we observed considerable increases in photovoltage responses, i.e., 5-fold increase for Nd3+, 10-fold for Er3+, and 13-fold for Nd3+/ Er3+, compared to the pristine SDNA due to the additional charge carriers generated in Ln3+-doped SDNA thin films. Device performance was measured in terms of photovoltage responsivity and retention characteristics. These phenomena indicate the high stability and substantial endurance characteristics of Ln3+-doped SDNA thin films.

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.

Topological, chemical and electro-optical characteristics of riboflavin-doped artificial and natural DNA thin films.

DNA is considered as a useful building bio-material, and it serves as an efficient template to align functionalized nanomaterials. Riboflavin (RF)-doped synthetic double-crossover DNA (DX-DNA) lattices and natural salmon DNA (SDNA) thin films were constructed using substrate-assisted growth and drop-casting methods, respectively, and their topological, chemical and electro-optical characteristics were evaluated. The critical doping concentrations of RF ([RF]C, approx. 5 mM) at given concentrations of DX-DNA and SDNA were obtained by observing the phase transition (from crystalline to amorphous structures) of DX-DNA and precipitation of SDNA in solution above [RF]C. [RF]C are verified by analysing the atomic force microscopy images for DX-DNA and current, absorbance and photoluminescence (PL) for SDNA. We study the physical characteristics of RF-embedded SDNA thin films, using the Fourier transform infrared spectrum to understand the interaction between the RF and DNA molecules, current to evaluate the conductance, absorption to understand the RF binding to the DNA and PL to analyse the energy transfer between the RF and DNA. The current and UV absorption band of SDNA thin films decrease up to [RF]C followed by an increase above [RF]C. By contrast, the PL intensity illustrates the reverse trend, as compared to the current and UV absorption behaviour as a function of the varying [RF]. Owing to the intense PL characteristic of RF, the DNA lattices and thin films with RF might offer immense potential to develop efficient bio-sensors and useful bio-photonic devices.

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.

Nature-Inspired Construction of Two-Dimensionally Self-Assembled Peptide on Pristine Graphene.

Peptide assemblies have received significant attention because of their important role in biology and applications in bionanotechnology. Despite recent efforts to elucidate the principles of peptide self-assembly for developing novel functional devices, peptide self-assembly on two-dimensional nanomaterials has remained challenging. Here, we report nature-inspired two-dimensional peptide self-assembly on pristine graphene via optimization of peptide-peptide and peptide-graphene interactions. Two-dimensional peptide self-assembly was designed based on statistical analyses of >104 protein structures existing in nature and atomistic simulation-based structure predictions. We characterized the structures and surface properties of the self-assembled peptide formed on pristine graphene. Our study provides insights into the formation of peptide assemblies coupled with two-dimensional nanomaterials for further development of nanobiocomposite devices.

M-DNA/Transition Metal Dichalcogenide Hybrid Structure-based Bio-FET sensor with Ultra-high Sensitivity.

Here, we report a high performance biosensor based on (i) a Cu2+-DNA/MoS2 hybrid structure and (ii) a field effect transistor, which we refer to as a bio-FET, presenting a high sensitivity of 1.7 × 103 A/A. This high sensitivity was achieved by using a DNA nanostructure with copper ions (Cu2+) that induced a positive polarity in the DNA (receptor). This strategy improved the detecting ability for doxorubicin-like molecules (target) that have a negative polarity. Very short distance between the biomolecules and the sensor surface was obtained without using a dielectric layer, contributing to the high sensitivity. We first investigated the effect of doxorubicin on DNA/MoS2 and Cu2+-DNA/MoS2 nanostructures using Raman spectroscopy and Kelvin force probe microscopy. Then, we analyzed the sensing mechanism and performance in DNA/MoS2- and Cu2+-DNA/MoS2-based bio-FETs by electrical measurements (ID-VG at various VD) for various concentrations of doxorubicin. Finally, successful operation of the Cu2+-DNA/MoS2 bio-FET was demonstrated for six cycles (each cycle consisted of four steps: 2 preparation steps, a sensing step, and an erasing step) with different doxorubicin concentrations. The bio-FET showed excellent reusability, which has not been achieved previously in 2D biosensors.

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.

Ultra-low Doping on Two-Dimensional Transition Metal Dichalcogenides using DNA Nanostructure Doped by a Combination of Lanthanide and Metal Ions.

Here, we propose a novel DNA-based doping method on MoS2 and WSe2 films, which enables ultra-low n- and p-doping control and allows for proper adjustments in device performance. This is achieved by selecting and/or combining different types of divalent metal and trivalent lanthanide (Ln) ions on DNA nanostructures, using the newly proposed concept of Co-DNA (DNA functionalized by both divalent metal and trivalent Ln ions). The available n-doping range on the MoS2 by Ln-DNA is between 6 × 10(9) and 2.6 × 10(10 ) cm(-2). The p-doping change on WSe2 by Ln-DNA is adjusted between -1.0 × 10(10) and -2.4 × 10(10 ) cm(-2). In Eu(3+) or Gd(3+)-Co-DNA doping, a light p-doping is observed on MoS2 and WSe2 (~10(10 ) cm(-2)). However, in the devices doped by Tb(3+) or Er(3+)-Co-DNA, a light n-doping (~10(10 ) cm(-2)) occurs. A significant increase in on-current is also observed on the MoS2 and WSe2 devices, which are, respectively, doped by Tb(3+)- and Gd(3+)-Co-DNA, due to the reduction of effective barrier heights by the doping. In terms of optoelectronic device performance, the Tb(3+) or Er(3+)-Co-DNA (n-doping) and the Eu(3+) or Gd(3+)-Co-DNA (p-doping) improve the MoS2 and WSe2 photodetectors, respectively. We also show an excellent absorbing property by Tb(3+) ions on the TMD photodetectors.

Coverage percentage and raman measurement of cross-tile and scaffold cross-tile based DNA nanostructures.

We present two free-solution annealed DNA nanostructures consisting of either cross-tile CT1 or CT2. The proposed nanostructures exhibit two distinct structural morphologies, with one-dimensional (1D) nanotubes for CT1 and 2D nanolattices for CT2. When we perform mica-assisted growth annealing with CT1, a dramatic dimensional change occurs where the 1D nanotubes transform into 2D nanolattices due to the presence of the substrate. We assessed the coverage percentage of the 2D nanolattices grown on the mica substrate with CT1 and CT2 as a function of the concentration of the DNA monomer. Furthermore, we fabricated a scaffold cross-tile (SCT), which is a new design of a modified cross-tile that consists of four four-arm junctions with a square aspect ratio. For SCT, eight oligonucleotides are designed in such a way that adjacent strands with sticky ends can produce continuous arms in both the horizontal and vertical directions. The SCT was fabricated via free-solution annealing, and self-assembled SCT produces 2D nanolattices with periodic square cavities. All structures were observed via atomic force microscopy. Finally, we fabricated divalent nickel ion (Ni(2+))- and trivalent dysprosium ion (Dy(3+))-modified 2D nanolattices constructed with CT2 on a quartz substrate, and the ion coordinations were examined via Raman spectroscopy.

Chemical and Physical Characteristics of Doxorubicin Hydrochloride Drug-Doped Salmon DNA Thin Films.

Double-stranded salmon DNA (SDNA) was doped with doxorubicin hydrochloride drug molecules (DOX) to determine the binding between DOX and SDNA, and DOX optimum doping concentration in SDNA. SDNA thin films were prepared with various concentrations of DOX by drop-casting on oxygen plasma treated glass and quartz substrates. Fourier transform infrared (FTIR) spectroscopy was employed to investigate the binding sites for DOX in SDNA, and electrical and photoluminescence (PL) analyses were used to determine the optimum doping concentration of DOX. The FTIR spectra showed that up to a concentration of 30 µM of DOX, there was a tendency for binding with a periodic orientation via intercalation between nucleosides. The current and PL intensity increased as the DOX concentration increased up to 30 µM, and then as the concentration of DOX further increased, we observed a decrease in current as well as PL quenching. Finally, the optical band gap and second band onset of the transmittance spectra were analyzed to further verify the DOX binding and optimum doping concentration into SDNA thin films as a function of the DOX concentration.

Construction and characterization of Cu²âº, Ni²âº, Zn²âº, and Co²âº modified-DNA crystals.

We studied the physical characteristics of modified-DNA (M-DNA) double crossover crystals fabricated via substrate-assisted growth with various concentrations of four different divalent metallic ions, Cu(2+), Ni(2+), Zn(2+), and Co(2+). Atomic force microscopy (AFM) was used to test the stability of the M-DNA crystals with different metal ion concentrations. The AFM images show that M-DNA crystals formed without deformation at up to the critical concentrations of 6 mM of [Cu(2+)], 1.5 mM of [Ni(2+)], 1 mM of [Zn(2+)], and 1 mM of [Co(2+)]. Above these critical concentrations, the M-DNA crystals exhibited deformed, amorphous structures. Raman spectroscopy was then used to identify the preference of the metal ion coordinate sites. The intensities of the Raman bands gradually decreased as the concentration of the metal ions increased, and when the metal ion concentrations increased beyond the critical values, the Raman band of the amorphous M-DNA was significantly suppressed. The metal ions had a preferential binding order in the DNA molecules with G-C and A-T base pairs followed by the phosphate backbone. A two-probe station was used to measure the electrical current-voltage properties of the crystals which indicated that the maximum currents of the M-DNA complexes could be achieved at around the critical concentration of each ion. We expect that the functionalized ion-doped M-DNA crystals will allow for efficient devices and sensors to be fabricated in the near future.

Energy band gap and optical transition of metal ion modified double crossover DNA lattices.

We report on the energy band gap and optical transition of a series of divalent metal ion (Cu(2+), Ni(2+), Zn(2+), and Co(2+)) modified DNA (M-DNA) double crossover (DX) lattices fabricated on fused silica by the substrate-assisted growth (SAG) method. We demonstrate how the degree of coverage of the DX lattices is influenced by the DX monomer concentration and also analyze the band gaps of the M-DNA lattices. The energy band gap of the M-DNA, between the lowest unoccupied molecular orbital (LUMO) and the highest occupied molecular orbital (HOMO), ranges from 4.67 to 4.98 eV as judged by optical transitions. Relative to the band gap of a pristine DNA molecule (4.69 eV), the band gap of the M-DNA lattices increases with metal ion doping up to a critical concentration and then decreases with further doping. Interestingly, except for the case of Ni(2+), the onset of the second absorption band shifts to a lower energy until a critical concentration and then shifts to a higher energy with further increasing the metal ion concentration, which is consistent with the evolution of electrical transport characteristics. Our results show that controllable metal ion doping is an effective method to tune the band gap energy of DNA-based nanostructures.

A 2D DNA lattice as an ultrasensitive detector for beta radiations.

There is growing demand for the development of efficient ultrasensitive radiation detectors to monitor the doses administered to individuals during therapeutic nuclear medicine which is often based on radiopharmaceuticals, especially those involving beta emitters. Recently biological materials are used in sensors in the nanobio disciplines due to their abilities to detect specific target materials or sites. Artificially designed two-dimensional (2D) DNA lattices grown on a substrate were analyzed after exposure to pure beta emitters, (90)Sr-(90)Y. We studied the Raman spectra and reflected intensities of DNA lattices at various distances from the source with different exposure times. Although beta particles have very low linear energy transfer values, the significant physical and chemical changes observed throughout the extremely thin, ∼0.6 nm, DNA lattices suggested the feasibility of using them to develop ultrasensitive detectors of beta radiations.