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

Gnapareddy, Bramaramba,Ahn, Sang Jung,Dugasani, Sreekantha Reddy,Kim, Jang Ah,Amin, Rashid,Mitta, Sekhar Babu,Vellampatti, Srivithya,Kim, Byeonghoon,Kulkarni, Atul,Kim, Taesung,Yun, Kyusik,LaBean, Tho Elsevier 2015 Colloids and surfaces Biointerfaces Vol.135 No.-

<P><B>Abstract</B></P> <P>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 <I>via</I> free-solution annealing, and self-assembled SCT produces 2D nanolattices with periodic square cavities. All structures were observed <I>via</I> atomic force microscopy. Finally, we fabricated divalent nickel ion (Ni<SUP>2+</SUP>)- and trivalent dysprosium ion (Dy<SUP>3+</SUP>)-modified 2D nanolattices constructed with CT2 on a quartz substrate, and the ion coordinations were examined <I>via</I> Raman spectroscopy.</P> <P><B>Highlights</B></P> <P> <UL> <LI> We present free-solution annealed DNA nanotubes and DNA nanolattices consisting of cross-tiles (CT1 and CT2) and a scaffold cross-tile (SCT). </LI> <LI> When we perform mica-assisted growth annealing with CT1, a dimensional change occurs where the 1D nanotubes transform into 2D nanolattices. </LI> <LI> We assessed the coverage percentage of the 2D nanolattices grown on the mica substrate as a function of the DNA concentration. </LI> <LI> Finally, we fabricated divalent and trivalent ion-modified 2D nanolattices which were examined via Raman spectroscopy. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

DNA and DNA–CTMA composite thin films embedded with carboxyl group-modified multi-walled carbon nanotubes

Dugasani, Sreekantha Reddy,Gnapareddy, Bramaramba,Kesama, Mallikarjuna Reddy,Ha, Tai Hwan,Park, Sung Ha Elsevier 2018 Journal of industrial and engineering chemistry Vol.68 No.-

<P><B>Abstract</B></P> <P>Although the intrinsic characteristics of DNA molecules and carbon nanotubes (CNT) are well known, fabrication methods and physical characteristics of CNT-embedded DNA thin films are rarely investigated. We report the construction and characterization of carboxyl (–COOH) group-modified multi-walled carbon nanotube (MWCNT–COOH)-embedded DNA and cetyltrimethyl-ammonium chloride-modified DNA (DNA–CTMA) composite thin films. Here, we examine the structural, compositional, chemical, spectroscopic, and electrical characteristics of DNA and DNA–CTMA thin films consisting of various concentrations of MWCNT–COOH. The MWCNT–COOH-embedded DNA and DNA–CTMA composite thin films may offer a platform for developing novel optoelectronics, energy harvesting, and sensing applications in physical, chemical, and biological sciences.</P> <P><B>Graphical abstract</B></P> <P>A facile methodology is developed to construct MWCNT–COOH-embedded DNA and DNA–CTMA composite thin films and distinct optoelectronic characteristics of the thin films are discussed.</P> <P>[DISPLAY OMISSION]</P>

Tailoring chemical and physical properties of graphene-added DNA hybrid thin films

Dugasani, Sreekantha Reddy,Gnapareddy, Bramaramba,Mitta, Sekhar Babu,Park, Sung Ha ELSEVIER 2019 CURRENT APPLIED PHYSICS Vol.19 No.3

<P><B>Abstract</B></P> <P>While the characteristics of DNA and graphene are well studied, the chemical and physical properties of graphene-embedded DNA and cetyltrimethyl-ammonium chloride-modified DNA (CT-DNA) hybrid thin films (HTFs) have been rarely discussed due to the limited development of fabrication methodologies. Herein, we developed a simple drop-casting method for constructing DNA and CT-DNA HTFs added with graphene nanopowder (GNP). Additionally, we demonstrated their distinct characteristics, such as their structure, elemental composition, spin states and chemical functional groups, binding interactions, vibration/stretching modes by UV–Vis absorption, PL, and electrical measurements. The EDS spectra of GNP-added DNA HTFs showed C, N, O, Na, and P peaks at characteristic energies. Because of the physical adsorption of GNP on DNA, the peak shifts and suppression of the core spectra of O 1s and P 2p were observed by XPS. The intensity variation of Raman and FTIR bands indicated hybrid formation of GNP in DNA and CT-DNA through adsorption, electrostatic interaction, and π–π stacking. UV–Vis absorption and PL spectra showed the considerable influence of GNP in DNA and CT-DNA HTFs. DNA and CT-DNA HTFs with relatively higher [GNP] showed significant increases of current due to the formation of interconnected networks of GNP in the DNA and CT-DNA HTFs.</P> <P><B>Highlights</B></P> <P> <UL> <LI> DNA and CTMA-DNA thin films with graphene are constructed by a drop-casting. </LI> <LI> Distinct characteristics of DNA and CTMA-DNA thin films with graphene are studied. </LI> <LI> The significance of optical spectroscopy and PL characteristics are discussed. </LI> <LI> Applications of DNA and CTMA-DNA thin films are addressed. </LI> </UL> </P>

Tailoring chemical and physical properties of graphene-added DNA hybrid thin films

Sreekantha Reddy Dugasani,Bramaramba Gnapareddy,Sekhar Babu Mitta,박성하 한국물리학회 2019 Current Applied Physics Vol.19 No.3

While the characteristics of DNA and graphene are well studied, the chemical and physical properties of graphene- embedded DNA and cetyltrimethyl-ammonium chloride-modified DNA (CT-DNA) hybrid thin films (HTFs) have been rarely discussed due to the limited development of fabrication methodologies. Herein, we developed a simple drop-casting method for constructing DNA and CT-DNA HTFs added with graphene nanopowder (GNP). Additionally, we demonstrated their distinct characteristics, such as their structure, elemental composition, spin states and chemical functional groups, binding interactions, vibration/stretching modes by UV–Vis absorption, PL, and electrical measurements. The EDS spectra of GNP-added DNA HTFs showed C, N, O, Na, and P peaks at characteristic energies. Because of the physical adsorption of GNP on DNA, the peak shifts and suppression of the core spectra of O 1s and P 2p were observed by XPS. The intensity variation of Raman and FTIR bands indicated hybrid formation of GNP in DNA and CT-DNA through adsorption, electrostatic interaction, and π–π stacking. UV–Vis absorption and PL spectra showed the considerable influence of GNP in DNA and CT-DNA HTFs. DNA and CT-DNA HTFs with relatively higher [GNP] showed significant increases of current due to the formation of interconnected networks of GNP in the DNA and CT-DNA HTFs.

Thickness, morphology, and optoelectronic characteristics of pristine and surfactant-modified DNA thin films

Arasu, Velu,Reddy Dugasani, Sreekantha,Son, Junyoung,Gnapareddy, Bramaramba,Jeon, Sohee,Jeong, Jun-Ho,Ha Park, Sung IOP 2017 Journal of Physics. D, Applied Physics Vol.50 No.41

<P>Although the preparation of DNA thin films with well-defined thicknesses controlled by simple physical parameters is crucial for constructing efficient, stable, and reliable DNA-based optoelectronic devices and sensors, it has not been comprehensively studied yet. Here, we construct DNA and surfactant-modified DNA thin films by drop-casting and spin-coating techniques. The DNA thin films formed with different control parameters, such as drop-volume and spin-speed at given DNA concentrations, exhibit characteristic thickness, surface roughness, surface potential, and absorbance, which are measured by a field emission scanning electron microscope, a surface profilometer, an ellipsometer, an atomic force microscope, a Kelvin probe force microscope, and an UV–visible spectroscope. From the observations, we realized that thickness significantly affects the physical properties of DNA thin films. This comprehensive study of thickness-dependent characteristics of DNA and surfactant-modified DNA thin films provides insight into the choice of fabrication techniques in order for the DNA thin films to have desired physical characteristics in further applications, such as optoelectronic devices and sensors.</P>

Magnetic studies of Co²⁺, Ni²⁺, and Zn²⁺−modified DNA double−crossover lattices

Dugasani, Sreekantha Reddy,Oh, Young Hoon,Gnapareddy, Bramaramba,Park, Tuson,Kang, Won Nam,Park, Sung Ha Elsevier 2018 APPLIED SURFACE SCIENCE - Vol.427 No.1

<P><B>Abstract</B></P> <P>We fabricated divalent-metal-ion-modified DNA double-crossover (DX) lattices on a glass substrate and studied their magnetic characteristics as a function of ion concentrations [Co<SUP>2+</SUP>], [Ni<SUP>2+</SUP>] and [Zn<SUP>2+</SUP>]. Up to certain critical concentrations, the DNA DX lattices with ions revealed discrete S-shaped hysteresis, <I>i.e.</I> characteristics of strong ferromagnetism, with significant changes in the coercive field, remanent magnetization, and susceptibility. Induced magnetic dipoles formed by metal ions in DNA duplex in the presence of a magnetic field imparted ferromagnetic behaviour. By considering hysteresis and the magnitude of magnetization in a magnetization-magnetic field curve, Co<SUP>2+</SUP>-modified DNA DX lattices showed a relatively strong ferromagnetic nature with an increasing (decreasing) trend of coercive field and remanent magnetization when [Co<SUP>2+</SUP>]≤1mM ([Co<SUP>2+</SUP>]>1mM). In contrast, Ni<SUP>2+</SUP> and Zn<SUP>2+</SUP>-modified DNA DX lattices exhibited strong and weak ferromagnetic behaviours at lower (≤1mM for Ni<SUP>2+</SUP> and ≤0.5mM for Zn<SUP>2+</SUP>) and higher (>1mM for Ni<SUP>2+</SUP> and >0.5mM for Zn<SUP>2+</SUP>) concentrations of ions, respectively. About 1mM of [Co<SUP>2+</SUP>], [Ni<SUP>2+</SUP>] and [Zn<SUP>2+</SUP>] in DNA DX lattices was of special interest with regard to physical characteristics and was identified to be an optimum concentration of each ion. Finally, we measured the temperature-dependent magnetic characteristics of the metal-ion-modified DNA DX lattices. Nonzero magnetization and inverse susceptibility with almost constant values were observed between 25 and 300K, with no indication of a magnetic transition. This indicated that the magnetic Curie temperatures of Co<SUP>2+</SUP>, Ni<SUP>2+</SUP> and Zn<SUP>2+</SUP>-modified DNA DX lattices were above 300K.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Co<SUP>2+</SUP>, Ni<SUP>2+</SUP>, and Zn<SUP>2+</SUP>-modified DNA lattices are fabricated on a substrate. </LI> <LI> Magnetic characteristics of divalent-metal-ion-modified DNA lattices are studied. </LI> <LI> The magnetic measurement of the sample shows unique ferromagnetic characteristics. </LI> <LI> The magnetic hysteresis suggests potential feasibility of use in memory devices. </LI> </UL> </P>

Energy Band Gap and Optical Transition of Metal Ion Modified Double Crossover DNA Lattices

Dugasani, Sreekantha Reddy,Ha, Taewoo,Gnapareddy, Bramaramba,Choi, Kyujin,Lee, Junwye,Kim, Byeonghoon,Kim, Jae Hoon,Park, Sung Ha American Chemical Society 2014 ACS APPLIED MATERIALS & INTERFACES Vol.6 No.20

<P>We report on the energy band gap and optical transition of a series of divalent metal ion (Cu<SUP>2+</SUP>, Ni<SUP>2+</SUP>, Zn<SUP>2+</SUP>, and Co<SUP>2+</SUP>) 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<SUP>2+</SUP>, 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.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/aamick/2014/aamick.2014.6.issue-20/am503614x/production/images/medium/am-2014-03614x_0006.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/am503614x'>ACS Electronic Supporting Info</A></P>

Optical Band Gap and Hall Transport Characteristics of Lanthanide-Ion-Modified DNA Crystals

Dugasani, Sreekantha Reddy,Ha, Taewoo,Kim, Si Joon,Gnapareddy, Bramaramba,Yoo, Sanghyun,Lee, Keun Woo,Jung, Tae Soo,Kim, Hyun Jae,Park, Sung Ha,Kim, Jae Hoon American Chemical Society 2015 The Journal of Physical Chemistry Part C Vol.119 No.25

<P>Lanthanide-ion-modified DNA crystals are fabricated on quartz and silica substrates via surface-assisted growth, and the optical band gap and electrical Hall transport are measured at room temperature for these crystals. The optical band gap of these crystals shows an increasing behavior, and the second band onset showed the inverted V shape upon increasing the lanthanide ion concentration. At a particular concentration, each lanthanide ion into the DNA crystals exhibited low resistivity, low Hall mobility, high free carrier concentration, and a minimum magneto resistance. The experimental results show feasibility in controlling important physical parameters, such as the band gap energy and Hall parameters, by adjusting the concentration of the lanthanide ion. When combined with the existing structural versatility of DNA nanostructures, these functional tunabilities will be crucial for the future development of DNA-based nanoelectronic and biophotonic devices.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jpccck/2015/jpccck.2015.119.issue-25/acs.jpcc.5b03875/production/images/medium/jp-2015-03875a_0003.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/jp5b03875'>ACS Electronic Supporting Info</A></P>

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

Kesama, Mallikarjuna Reddy,Dugasani, Sreekantha Reddy,Yoo, Sanghyun,Chopade, Prathamesh,Gnapareddy, Bramaramba,Park, Sung Ha American Chemical Society 2016 ACS APPLIED MATERIALS & INTERFACES Vol.8 No.22

<P>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 (Tb3+-Tm3+, Tb3+-Eu3+, and Tm3+-Eu3+) and a triple Ln3+-dopant pair (Tb3+-Tm3+-Eu3+) with different types of Ln3+, (i.e., Tb3+ chosen for green emission, Tm3+ for blue, and Eu3+ for red), as well as various concentrations of Ln(3+) for enhancement of specific functionalities. We estimate the optimum concentration of Ln(3+) ([Ln3+]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.</P>

Fabrication and optoelectronic characterisation of lanthanide- and metal-ion-doped DNA thin films

Dugasani, Sreekantha Reddy,Paulson, Bjorn,Ha, Taewoo,Jung, Tae Soo,Gnapareddy, Bramaramba,Kim, Jang Ah,Kim, Taesung,Kim, Hyun Jae,Kim, Jae Hoon,Oh, Kyunghwan,Park, Sung Ha IOP 2018 Journal of Physics. D, Applied Physics Vol.51 No.28

<P>DNA molecules doped with lanthanide and metal ions possess distinct functionalities, providing a feasibility to be utilised in various applications in nano- and biotechnologies. In the present work, we fabricate DNA thin films doped with seven different lanthanide ions (Ce<SUP>3+</SUP>, Dy<SUP>3+</SUP>, Eu<SUP>3+</SUP>, Gd<SUP>3+</SUP>, Tb<SUP>3+</SUP>, Tm<SUP>3+</SUP>, and Sm<SUP>3+</SUP>) and four different metal ions (Cu<SUP>2+</SUP>, Ni<SUP>2+</SUP>, Zn<SUP>2+</SUP>, and Co<SUP>2+</SUP>) by the drop-casting method. In addition, we conduct current, Hall transport, optical transmittance, and Raman spectroscopic measurements to investigate their electrical properties, carrier concentrations and Hall mobilities, optical band gaps, and vibrational and stretching modes, respectively. By analysing the current–voltage characteristics of the doped thin films with varying dopant concentrations, characteristic critical concentrations are observed, which are related to the significant enhancement of the thin film’s physical properties, compared with the pristine DNA. The extrema of the carrier concentrations and Hall mobilities of the doped thin films were observed approximately at the same critical concentrations. The optical band gaps gradually decreased with an increasing dopant concentration, caused by the intrinsic characteristics of both the dopants and DNA. Because of the preference of ions binding to DNA backbones through an electrostatic attraction and to bases via intercalation, the Raman band intensities gradually increase (or decrease) until reaching [Ln]<SUB>C</SUB> (or [M]<SUB>C</SUB>), where their trend is reversed. Ln-DNA and M-DNA thin films provide significant, specific, and novel physical characteristics which can be used in various applications.</P>