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Thermogravimetric analysis (TGA) and differential thermal analysis (DTA) of the TiO 2 nanomaterials in DNA. Curve A and B show the TGA and DTA curve of TiO 2 nanomaterials having wire-like structure, respectively.
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A new route for the formation of wire-like clusters of TiO2 nanomaterials self-assembled in DNA scaffold within an hour of reaction time is reported. TiO2 nanomaterials are synthesized by the reaction of titanium-isopropoxide with ethanol and water in the presence of DNA under continuous stirring and heating at 60 °C. The individual size of the TiO...
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Context 1
... Raman spectra of the wire-like TiO 2 nanomaterials obtained aer annealing the sample above 550-600 C is presented in Fig. S-4 À1 , which are absent in our prepared sample, indicating that the synthesized DNA-TiO 2 nanomaterials only belong to the anatase ...
Context 2
... thermogravimetric analysis (TGA) and differential thermal analysis (DTA) were carried out to examine the thermal stability and the crystalline condition of the DNA-TiO 2 nanomaterials. The as-prepared TiO 2 nanomaterials were heated from RT to 1000 C with an increment of 10 C min À1 in air. Curves A and B in Fig. 4 show the TGA and DTA curves of TiO 2 nanomaterials having a wire-like structure. From the TGA curve, we can see that the rst weight loss occurs near 100 C, indicating that the excess ethanol and water molecules started to evaporate from the sample. Another weight loss occurs above 100 C to below 400 C, which could be attributed to the ...
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Hierarchical porous β-MnO2 nanoflowers self-assembled by ultrathin (thickness less than 10 nm) nanoplates have been successfully fabricated at room temperature. Because of its high specific surface area (267 m2 g−1) and proper pore size distributions (average pore size, ca. 5.9 nm), the obtained 3D nanomaterials achieve enhanced capacitance as high...
A new approach is developed for the aqueous phase formation of flake-like and wire-like β-MnO2 nanomaterials on a DNA scaffold at room temperature (RT) within a shorter time scale. The β-MnO2 nanomaterials having a band gap energy ∼3.54 eV are synthesized by the reaction of Mn(ii) salt with NaOH in the presence of DNA under continuous stirring. The...
Citations
... In 1998, Braun et al. reported DNA-templated Ag nanowires. [55] After this pioneering study, DNA-templated metal nanowires have been produced using a variety of metals, including Ag, [56,57] Au, [58,59] Cd, [60,61] Co, [62] Cu, [63] Fe, [64] Ni, [65] Pd, [66,67] Pt, [68,69] Rh, [70] Te, [71] Ti, [72] and MoGe alloys. [73] DNA nanotechnology has advanced the fabrication of various DNA nanostructures, which allows metal nanostructures to have sophisticated 2D and 3D geometries. ...
... [61] Kundu et al. also synthesized DNA-templated TiO 2 nanowires by microwave heating. [72] Nithiyanantham et al. used a microwave heating approach to synthesize DNA-templated Os nanowires by microwave irradiation on a mixture of DNA templates and Os ions in the presence of ethanol functioning as reducing agents as shown in Figure 8A. [121] The metal growth of Au by microwave heating is fast and simple as shown in Figure 8B; [59] however, it is important to maintain the stability of the DNA templates under microwave irradiation. ...
Electron microscopy‐based DNA imaging is a powerful tool that provides a high resolution for observing genomic structures involved in biochemical processes. The first method, heavy metal shadow casting, was developed in 1948. Uranyl acetate has been widely used for DNA electron microscopic imaging since the 1960s. However, for this method, scientists must deal with government regulations for the safety and disposal. Additionally, sample preparation is often complicated and time‐consuming. Recently, nanoparticles and nanowires have emerged as a new way of imaging DNA molecules under both transmission and scanning electron microscopes. However, as this technology is still in its early stages, there is room for further development. In this review, heavy metal staining, nanoparticle staining, and nanowire growth for DNA visualization are introduced. The applications of shadow casting and uranyl acetate staining in the visualization of DNA structures and protein–DNA complexes are discussed. Then, nanomaterial‐based DNA staining methods are covered, including electrostatic interactions, DNA chain modification, reducing‐group‐modified DNA ligands and DNA–peptide/protein interactions. This review provides up‐to‐date information on different DNA staining approaches and their applications in DNA studies. Ultimately, it offers a new direction for genome analysis through DNA visualization. This review provides a summary of the various methods for visualizing DNA using electron microscopy, including heavy metal staining, nanoparticle staining, and nanowire growth. They offer high‐resolution imaging of DNA structures, DNA conformation, and protein‐DNA interactions. The aim is to provide a comprehensive overview of the DNA staining methods for further research and development in this field.
... Metal and metal oxide nanoparticles (NPs) have emerged as functional materials of high scientific interest for diverse applications in health, energy, and environmental domains. 1 The functional properties of metal and metal oxide NPs stemming from their optical and electronic characteristics can be tuned by controlling their physicochemical properties. 2 NPs with desired physicochemical properties of NPs, including size, morphology, bulk, and surface chemistry, can be produced by employing suitable NP fabrication methods. [3][4][5][6][7][8][9][10][11][12][13][14] Among all the available NPs fabrication methods, the chemical reduction method involving the reduction of metal salts in the presence of a stabilizing agent is the most commonly used method. [15][16][17][18] During the chemical reduction method, high surface energy can lead to the agglomeration of particles. ...
We report the synthesis and electrocatalytic activity of poly(3‐hexylthiophene) stabilized nickel oxide nanoparticles (P3HT@NiO NPs). Employing semiconducting P3HT as a stabilizing agent produced well dispersed P3HT@NiO NPs with uniform size distribution (2.5 ± 1.2 nm). For comparison, NiO NPs stabilized with the small molecule 3‐hexylthiophene (3HT@NiO NPs) were also synthesized and characterized as reference material. The physiochemical properties of the developed hybrid P3HT@NiO were fully characterized using UV/Vis absorption spectroscopy, fluorescence spectroscopy, high resolution transmission electron microscopy (HRTEM) and X‐ray photoelectron spectroscopy (XPS). The electrocatalytic activities of the developed semiconducting polymer‐stabilized NPs were evaluated for the oxygen evolution reaction (OER) of water splitting. Our work reveals the electronic communication between P3HT and NiO NPs and demonstrates that P3HT@NiO NPs exhibit superior catalytic activity with an overpotential of 310 mV when compared to the reference 3HT@NiO NPs which exhibited an overpotential 560 mV. These results suggest that the heteroatom‐containing π‐conjugated semiconducting polymers can be employed as electrocatalytic performance enhancing and stabilizing ligands for the synthesis of ultrafine metal‐based NPs as efficient electrocatalytic platforms.
... The development of promising photovoltaic system depends on synthesis of high light absorbing materials [34], formulation of electrolyte with efficient iodine/triiodide redox couple, and preparation of photoanode using various semiconductor nanomaterials [5,6]. Accordingly, several semiconductors have been utilized to produce novel nanostructures comprising TiO2, ZnO, Nb2O5, SrTiO3, Zn2SnO4, etc. [7][8][9][10][11][12]. Among them, strontium titanate (SrTiO3), a n-type perovskite material with an indirect bandgap energy of ~3.2 eV to 3.4 eV, has been broadly examined, due to its superior photocorrosion resistibility, thermal stability, electrical properties [13][14], and structural similarities with anatase titanium dioxide (TiO2). ...
Plasmonic silver nanoparticles loaded strontium titanate nanocomposites (Ag-SrTiO3 NC) with diverse weight percentages (0.5, 1.5, 2.5 and 5 wt%) of Ag nanoparticles (Ag NPs) are synthesized by a facile chemical reduction method. The prepared nanocomposites are characterized using diffuse reflectance spectroscopy, X-ray diffractometry, photoluminescence spectroscopy, scanning electronic microscopy and transmission electron microscopy. The photovoltaic performance of dye-sensitized solar cells (DSSCs) integrated with Ag-SrTiO3 NC photoanodes has been assessed under simulated sun light intensity of 100 mW cm–2. The Ag-SrTiO3 NC photoanode loaded with 2.5 wt% Ag NPs exhibited higher power conversion efficiency of 4.39% with short-circuit photocurrent density of 11.54 mA cm⁻², open circuit voltage of 0.77 V and fill factor of 0.49 in DSSC. This enhanced photovoltaic performance can be credited to high dye loading, improvement in visible light harvesting property and fast photo-induced electron transfer caused by the plasmonic Ag NPs.
... Peptides have been used as templates for the development of dye-sensitized solar cells [271,272]. Hollow TiO 2 nanoribbons are produced by depositing a TiO 2 layer on self-assembled aromatic dipeptide nanoribbons followed by pyrolysis (Fig. 22b) [272]. These nanoribbons may be used as photoanodes to improve the power conversion efficacy of dye-sensitized solar cells. ...
... Peptides have been used as templates for the development of dye-sensitized solar cells [271,272]. Hollow TiO 2 nanoribbons are produced by depositing a TiO 2 layer on self-assembled aromatic dipeptide nanoribbons followed by pyrolysis (Fig. 22b) [272]. These nanoribbons may be used as photoanodes to improve the power conversion efficacy of dye-sensitized solar cells. ...
... [269], copyright 2014, with permission from Wiley-VCH Verlag. Image (b) was reproduced from Ref. [272], copyright 2010, with permission from IOP Publishing. Image (c) was reproduced from Ref. [274], copyright 2011, with permission from Nature. ...
Throughout the course of evolution, organisms have produced biominerals with hierarchical structures derived from organic templates. Over the last couple of decades, scientists have adopted sophisticated structures as templates for preparing pure or hybrid inorganic materials that bear the same morphologies as their biological counterparts. The present review provides a broad overview on the state-of-the-art research in the field of mineralized inorganic and hybrid materials, using functional biological or synthetic templates that have been adopted for biomedical, physical, chemical and environment applications. The synthesis, properties, and progress of these bio-inspired materials are reviewed to provide a backdrop for future research in various arenas.
... In the first region, the weight loss observed between room temperature and 150 °C become around 1.70%; it is due to the elimination of excess solvents and physisorbed water molecules on the surface of TiO 2 . In the second region, weight loss of 0.56% was observed within the temperature range 150-350 °C, which could be attributed to the removal of chemisorbed water molecules and unhydrolyzed isopropoxide [54,55]. In fact, in the TGA curve at the third region 350-750 °C, no significant weight loss is observed (0.043%). ...
Herein, we report the collection of TiO2 nanopowder after successful thin film deposition. The obtained TiO2 nanopowder was utilized for photodegradation of 4-nitrophenol (4-NP). The structural, optical, morphological, thermal and photocatalytic properties of TiO2 photocatalyst were systematically studied using XRD, Raman, HR-TEM, FT-IR, FE-SEM, EDS, UV–Vis, DRS, PL, BET and TGA. From XRD, we correlate crystallinity parameters like crystallite domain size, lattice cell parameters, unit cell volume, microstrain, stacking fault and dislocation density. TiO2 nanopowder annealed at 400 °C shows the anatase phase which is confirmed by Raman and XRD analyses. In addition, optical results indicate that the absorption band edge is positioned in the UV region with bandgap energy of 3.03 eV. The FE-SEM and TEM images of TiO2 nanopowder show irregular spherical morphology which results in the aggregation of nanoparticles with a mean diameter of 27 nm. From Brunauer–Emmett–Teller (BET) adsorption isotherm, the surface area was obtained to be 38 m²/g. The TGA curve demonstrates the thermodynamically stable anatase phase of TiO2 photocatalyst appeared in the 350–750 °C. Under UV light irradiation, photodegradation of 4-NP over 1.5 g/dm³ TiO2 photocatalyst dose achieved an excellent degradation efficiency and COD removal efficiency around 99.51 and 82% within 80 min, respectively. From trapping experiments, it indicates that OH· and O 2· radicals are major reactive oxygen species involved in the photodegradation of 4-NP.
... The particles in diluted TiBALDH of 5.2 nm disappeared aer the mixture with DNA, indicating that all TiO 2 particles condensed in a hybrid structure DNA-TiO 2 . Nithiyanantham et al. 46 reported the synthesis of similar structures using DNA and Ti alkoxide in a mixture of water/ ethanol. Ti alkoxides are very reactive in that conditions forming hydroxy(oxo)titanium aggregates, however in presence of DNA and further annealing result in TiO 2 wire-like structures, showing the scaffolding role of the DNA. ...
Titanium(IV) bis(ammonium lactate)dihydroxide (TiBALDH) is a commercially available reagent frequently used to synthesize TiO2. Particularly, for the biomimetic synthesis of TiO2, TiBALDH is the preferred precursor because it can be mixed in aqueous solutions with no apparent hydrolysis or condensation reactions. Thus, proteins or other biomolecules can be used as a template in aqueous systems for the synthesis of TiO2 from TiBALDH. Nevertheless, there is evidence that TiBALDH is in equilibrium with TiO2, and even, the principal structure of the complex has been suggested as [Ti4O4(lactate)8]⁸⁻. Since that chemical equilibrium depends on the polarity of the solvent, in this work we explored a diversity of media to test the chemical stability of TiBALDH and its equilibrium with TiO2 at room temperature. TiBALDH (2.078 M) contains particles of 18.6 ± 7.3 nm in size, if it is diluted with deionized water, the particles reach a size of 5.2 ± 1.7 nm, which suggest that intermolecular interactions form polymers of titanium lactate complexes reversibly, reaching equilibrium after 10 hours. Typical buffer systems were tested; TiBALDH reacted rapidly only with phosphate groups, even if the source came from DNA. Therefore, phosphate buffer must be avoided in biomineralization TiO2 synthesis. In solutions of TiBALDH at basic pH, condensation reactions are promoted to form a gel containing anatase nanoparticles, but if the solutions are acidic, monodisperse anatase nanoparticles of ∼5 nm were observed. The results show that the commercial reagent TiBALDH contains many species of titanium lactate complexes in equilibrium with TiO2, and it is affected by the concentration, time, pH, and several ions. This peculiar behavior must be taken into account when this precursor is used and it could be useful to develop novel synthesis routes of macrostructures with biomolecules in aqueous systems.
... TiO 2 NPs were selfassembled on a DNA template to form a linear structure through simple electrostatic interaction and covalent modifications. 208 The obtained DNA-TiO 2 1D nanowires were proved to be good anode materials for solar cells with a high cycle life. In addition, TiO 2 can combine with CNTs to form composite nanomaterials by using viruses as templates. ...
... Nithiyanantham et al. designed a novel route to assemble TiO 2 into wire-like clusters on a DNA template for supercapacitor applications. 208 DNA was combined with TiO 2 through a simple electrostatic interaction between DNA and a Ti salt and subsequent heating (Fig. 22a). DNA as an electronegative structural template attracted metal cations to bind along the DNA scaffold. ...
Bioinspired synthesis offers potential green strategies to build highly complex nanomaterials by utilizing the unique nanostructures, functions, and properties of biomolecules, in which the biomolecular recognition and self-assembly processes play important roles for tailoring the structures and functions of bioinspired materials. Further understanding of biomolecular self-assembly for inspiring the formation and assembly of nanoparticles would promote the design and fabrication of functional nanomaterials for various applications. In this review, we focus on recent advances in bioinspired synthesis and applications of hierarchical nanomaterials based on biomolecular self-assembly. We first discuss the biomolecular self-assembly towards biological nanomaterials, in which the mechanisms and ways of biomolecular self-assembly as well as various self-assembled biomolecular nanostructures are demonstrated. Secondly, the bioinspired synthesis strategies including molecule-molecule interaction, molecule-material recognition, molecule-mediated nucleation and growth, and molecule-mediated reduction/oxidization are introduced and discussed. Meanwhile, typical examples and discussions on how the biomolecular self-assembly inspires the formation of hierarchical hybrid nanomaterials are given. Finally, the applications of bioinspired nanomaterials in biofuel cells, light-harvesting systems, batteries, supercapacitors, catalysis, water/air purification, and environmental monitoring are presented and discussed. We believe that this review will be very helpful for readers to understand the self-assembly of biomolecules and the biomimetic/bioinspired strategies for synthesizing functional bionanomaterials in one way, and in another way it is valuable to design novel materials for extended applications in nanotechnology, materials science, analytical science, and biomedical engineering.
... The EDS experiments showed that atomic percent of Au reached from zero at bare PGE to 0.88 at PMET-AuNPs/PGE and to 0.99 at DNA/PMET-AuNPs/PGE which it confirms deposition of Au. On the other hand, atomic percent of P from zero at bare PGE and PMET-AuNPs/PGE, increased to 0.2 at DNA/PMET-AuNPs/PGE which it is attributed to the presence of DNA (Nithiyanantham et al., 2014). ...
The present work describes an ultrasensitive electrochemical sensor for determination of mercury(II) using deoxyribonucleic acid/poly-L-methionine-gold nanoparticles/pencil graphite electrode (DNA/PMET-AuNPs/PGE). To fabricate this biosensor, L-methionine (L-MET) was electropolymerized on the PGE surface followed by simultaneous electrochemical entrapment of AuNPs. Next, DNA was immobilized on the PMET-AuNPs/PGE by applying a 0.5 V potential. The surface area of modified and unmodified electrodes was determined by chronocoulometric technique. Hg²⁺ was detected in the linear dynamic range of 0.1 aM to 0.1 nM, and the detection limit was determined as 0.004 aM using square wave anodic stripping voltammetry (SWASV) under optimized conditions. The DNA/PMET-AuNPs/PGE demonstrated good selectivity toward Hg²⁺ against other metal ions such as V⁴⁺, Pb²⁺, Cr³⁺, Cd²⁺, Cu²⁺, Zn²⁺, Sn²⁺, In³⁺, Ge⁴⁺, and Fe³⁺. Real samples studies were carried out in sea water and fish samples.
... Moreover, the inaccessibility of all PAM signals in calcined porous NS TiO 2 beads sample may not just justify its removal, but a highly intense signal at 494 cm À1 is considered as the signature of the characteristic Ti-O-Ti bonds. 53,54 The PXRD patterns were recorded to determine the structural properties of PAM, PAM-TiO 2 NC and porous TiO 2 beads. The at lines with small humps were appeared in PAM and PAM-TiO 2 NC beads due to the absence and presence of amorphous TiO 2 respectively. ...
Nano/microscale TiO2 materials and their composites have reached the pinnacle of their photocatalytic performances to destroy persistent organic pollutants and waterborne microorganisms, but their practical applications are limited by the drawbacks associated with their stability, leaching, processing and separation. To overcome these shortcomings, we have prepared hierarchically porous nanostructured TiO2 macrobeads via an exotemplating or nanocasting strategy by infiltrating the TiO2 sol into the emulsion-templated porous polyacrylamide scaffold followed by its gelation, drying and calcination. The nanoscale TiO2 building units tailor the shape of the porous polymeric network after calcination thereby retaining the macroscale morphology of polymer beads after template removal. A novel combination of the hierarchical macroporosity, orderly crystalline anatase nature, nanoscale feature and good surface area revealed by the relevant characterization tools makes these TiO2 scaffolds particularly effective for superior degradation of methylene blue with the enhanced rate constant and efficient disinfection of E. coli and S. aureus under UV light. The macrosize and mechanical stability of these purely TiO2 beaded architectures have several potential advantages over conventional TiO2 nanocomposites and slurry systems to address the inherent bottlenecks of secondary contamination, difficult operation and energy-intensive post-recovery processes that are indeed deemed to be the barriers to develop practically useful water treatment technologies.
... Such embedded scatterers do not involve any further fabrication step without increasing the internal resistance of the device and hindering the charge injection from the sensitizer. 26 In this context, materials with various morphologies like larger particles, 27 spherical aggregates of nanocrystals, 28 hollow microspheres, 29 and spherical voids, 30 clusters of self-assembled nanomaterials, 31 as well as materials with different refractive indexes, e.g., SnO 2 , SiO 2 , CeO 2 , etc., have been explored as light scattering materials. 32−34 On the other hand, in the DSSC, intrinsically complex and competitive interfacial processes exist at semiconductor/redox couple interface, sensitizer/redox couple interface, and FTO/redox couple interface, where charge carriers in separate phases come across each other following physical interactions. ...
The light harvesting effects along with the energy barrier properties in dye sensitized solar cells (DSSCs) have been studied by utilizing an easily synthesizable and cost effective nanocube assembled micron sized SrTiO3 (STO NCMS) in a binary hybrid photoanode with ZnO nanoparticles. An optimized photoanode loaded with 3% STO NCMS yielded a ~ 2-fold increment in power conversion efficiency compared to pristine ZnO NP based device. Improved performance of photoanode with hybrid composite scaffold can be accredited to the boosted optical response in chorus with impeded reverse tunneling probability of STO NCMS containing photoanode. Micron sized STO NCMS provides a better light absorption in the photoanodes owing to optical confinement of incident light by multiple reflections generated from mirror like facets of SrTiO3 nanocubes as well as an enhanced light scattering effects from individual entity. IPCE analysis revealed a better absorption of low energy photons that in turn resulted in an enhanced solar to electricity generation for an optimized ratio of STO NCMS. An effective photoinduced charge separation has been achieved with a uniquely aligned band structure, resulting in an enhanced power conversion efficiency. Electrochemical Impedance analysis unveiled that incorporation of STO NCMS can effectively prolong life time of photo injected electron (τe) as well as a higher value of recombination resistance (Rrec) at semiconductor/dye/electrolyte hetero-interface indicating an impeded reverse tunneling probability of photo-injected electrons.
