The nuclear disasters of Chernobyl and Fukushima presented an urgent need for finding solutions to treatment of radioactive wastes. Among the by-products of nuclear fission is radioactive Cs-137, which evokes an environmental hazard due to its long half-life (> 30 years) and high solubility in water. In this work, a water-soluble organic ligand, readily obtained from alloxan and 1,3,5-benzenetriol, has been found to selectively bind and precipitate Cs+ ions from aqueous solutions. The special rigid structure of the ligand, which consists of a ``tripodal'' carbonyl base above and below an aromatic plane, contributes to the size-driven selectivity towards the large Cs+ ions and the formation of a giant, insoluble supramolecular complex. In addition to the low costs of the ligand, high yields and effectiveness in precipitating Cs+ ions, the Cs- complex revealed a high endurance to continuous doses of gamma-radiation, increasing its potential to act as a precipitating agent for Cs-137.
Controlling the permeability and porosity of an inorganic layer using biomolecule building blocks has raised interest for nanotechnological applications. The challenge lies mostly in the fabrication, usually a long, expensive and tedious process, involving many steps. Using biomaterials for this purpose is highly appealing; due to both ease of fabrication and the final output, that contains a bioelement. The biomolecule, specifically, stable protein 1 (SP1), serving as the scaffold for our pattern, is of great stability and durability, and presents size, charge and structural selectivity towards electroactive species. Here, we demonstrate the ability of SP1 to form a rigid template within a sol-gel matrix, allowing selective electron transfer to the gold electrode. Specifically, a thiolated SP1 was first adsorbed on a gold surface followed by filling the non-occupied areas by sol-gel. The latter was electrochemically deposited. The various steps were carefully characterized. Finally, we studied the electrochemistry of numerous redox couple at the Au/SP1/sol-gel interface and found that the nanochannel array shows charge and structural selectivity, which is based on the interactions between the redox species and the functionalities of SP1. The resulted surface shows promise towards electrochemical sensing applications.
The development of printed electronics has gained much attention as an alternative for conventional metal-based electronics, mainly due to the ability to print electronic circuits on plastics and by much cheaper means as compared with conventional microelectronics. Here we report on a single stage formation of a highly corrosion resistance coating with hydrophobic properties on printed-Cu nanoparticles. Our method is based on the synergistic effect of benzotriazole (BTA) as corrosion inhibitor and trimethylsiloxysilicate (TMS) as hydrophobic component. Printed-Cu coated with such TMS/BTA layer exhibited excellent corrosion resistance in 3.5% NaCl solution, reducing the dissolution of Cu into soluble species by one order of magnitude.
More than 50% of solar energy comes from the infrared region (as radiant heat) of the solar spectrum. Electrochromic (EC) materials, which can dynamically modulate the transmittance of infrared (IR) radiation, can be effectively applied in smart windows for thermal management in buildings. In this work, a core-shell TiO2-WO3 inverse opal (IO) structure was fabricated through the electrodeposition of WO3 onto TiO2 IO templates. The TiO2 IO templates were synthesized by introducing TiO2 into the voids of a polystyrene (PS) colloidal crystal template, followed by calcination to remove the PS microspheres. It was found that the TiO2-WO3 IO core-shell structure can modulate NIR transmittance at wavelengths from 700 to 1600 nm in the NIR range when potential is applied in LiClO4/PC electrolyte. When -0.3 V is applied, up to 60% of NIR radiation in this range can be blocked. The NIR transmittance can be modulated by tuning the applied potential. This study focuses on comparing the novel TiO2-WO3 IO structure with electrodeposited WO3 thin film to fully elucidate the effect of the inverse opal morphology and the TiO2-WO3 hybrid system on the optical properties. Results show that the NIR blockage can be sustained up to 90% after 1200 reversible cycles for TiO2-WO3 IO structure. The greater surface area of the IO structure increases the number of active sites available for the redox reactions by providing a larger contact area with the electrolyte. The more electroactive area with improved charge transfer enhances the overall NIR transmittance contrast as compared to bulk WO3 thin film. Furthermore, the addition of WO3 to TiO2 to form a composite has been shown to enhance cycling performance and device lifespan.
We present a novel gas phase detection prototype based on assembling core-shell nanospheres made of a silver core and coated with a molecularly imprinted polymer (MIP) adsorbed onto an interdigitated array (IDA) electrode chemiresistor (CR). The core-shell nanospheres, AgNP@MIPs, were imprinted with linalool, a volatile terpene alcohol, as a model system. The thickness of the MIP layer was tuned to a few nanometers to enable the facile ingress and egress of the linalool, as well as to enhance the electrical transduction through the Ag core. The AgNP@MIPs were spread onto the IDA-CR modified with various positively charged polymers, by drop casting and dip-coating. The AgNP@MIPs were characterized by various techniques such as extra high-resolution scanning and tunnelling electron microscopy and X-ray diffraction. The MIP recognition event was transduced into a measurable increase in the resistance. The response to linalool exposure and removal was fast and the device was fully recovered and could be reused. Finally, the difference in the resistance change between imprinted and non-imprinted nanospheres was substantial.
The sensing performance of a Langmuir-Blodgett monolayer was significantly improved by controlling the film organization at the air-water interface. Cellulose acetate (CA) and 4-tert-butylcalix  arene (calix) were co-spread and formed a Langmuir film, which was efficiently transferred onto a preoxidized gold electrode, Au-ox. The modified gold electrode was applied as a fast, highly sensitive electrochemical sensing platform for the quantitative determination of a model molecule, dopamine (DA). The modified gold electrode, CA-calix/Au-ox, demonstrated better recognition and sensing ability towards dopamine as compared with electrodes modified by a single component. Under the optimized conditions, the reduction peak currents at the CA-calix/Au-ox increased linearly within the concentration range of dopamine from 5 to 100 and 100-7500 nM, and exhibited a very low limit of detection (LOD) of 2.54 nM (S/N = 3). These results suggest a simple, superior and efficient approach for the controllable rearrangement of Langmuir-Blodgett monolayers on a molecular level. The electroanalytical performance was optimized from the perspective of the electrode-electrolyte interface. (C 2018 Elsevier B.V. All rights reserved.
Nanoparticles imprinted matrices (NAIMs) is a new approach, in which nanoparticles (NPs) are imprinted in a matrix followed by their removal to form highly selective voids that can recognize the original NPs. In this study, the effect of a sol-gel matrix on the imprinting and reuptake of gold nanoparticles (AuNPs) is examined. Specifically, indium tin oxide (ITO) films were modified with a positively charged polymer, on which the negatively charged AuNPs stabilized with citrate (AuNPs-cit) were adsorbed. This was followed by the electrochemical deposition of sol-gel matrices with different thicknesses and functional groups onto the ITO/AuNPs-cit. Electrochemical oxidation dissolved the AuNPs-cit and formed cavities in the sol-gel films, which fit both the size and shape of the AuNPs-cit. Reuptake of these NPs from an aqueous solution was successful using the imprinted films, whereas the non-imprinted films did not re-uptake the AuNPs-cit. Furthermore, the thickness of the sol-gel layers as well as the type of the silanes that were deposited play an important role on the recognition ability of the NAIM. Finally, we found that the NAIMs are selective, and larger AuNPs-cit were not recognized by the imprinted matrix.
Understanding the nature of interactions between inorganic surfaces and biomolecules, such as amino acids and peptides, can enhance the development of new materials. Here, we present single molecule force spectroscopy (SMFS) measurements of the interactions between an atomic force microscopy (AFM) probe, modified with various amino acids, and a titanium dioxide surface. Specifically, we study the affinity of amino acids toward a titanium dioxide surface bearing hydrophobic (Leu), aromatic (Phe) and hydrophilic (Orn) residues. We find that aromatic interactions dominate over aliphatic in their affinity to the titanium dioxide surface. In addition, we show that by combining aromatic and hydrophilic moieties in a single amino acid (NH2-Phe), the adhesion of the latter to the surface increases. Furthermore, the affinity of positively charged amino acids to the titanium dioxide surface is higher than that of uncharged, and can be increased more, with elevating the pH of the buffer above the pK(a) of the basic residues. The kinetic and thermodynamic parameters imply that the dynamics of the surface-amino acid interface are mostly governed by hydrophobic interactions.
A fast, ultrasensitive electrochemical sensing platform based on graphitic carbon nitride-electrochemically deposited-poly(3,4-ethylenedioxythiophene) (g-C3N4-E-PEDOT) composite was constructed by in-situ electropolymerization and applied for the quantitative determination of acetaminophen (AP). E-PEDOT was introduced as the conducting matrix for developing g-C3N4 composite to complement the poor conductivity disadvantage of g-C3N4. The strong affinity and synergetic effect between g-C3N4 and E-PEDOT, which were analyzed by PM6 computational calculation, highly improved the electron transfer property and remarkably enhanced the electrochemical catalytic activity of the composite. The g-C3N4-E-PEDOT modified glassy carbon electrode (GCE) demonstrated better electrocatalytic activity towards the oxidation of AP than bare, g-C3N4 and E-PEDOT modified ones. Under the optimized conditions, the oxidation peak currents at the g-C3N4-E-PEDOT/GCE increased linearly in the concentration range of AP from 0.01 to 2 mu M and 2-100 mu M, and an ultra-low limit of detection (LOD) of 34.28 nM was obtained (S/N = 3). In addition, the g-C3N4-E-PEDOT/GCE was successfully applied for the AP determination in the clinical human serum, and also exhibited excellent selectivity, reproducibility and stability. Except the novel AP determination approach, moreover, this work provided a new electrochemical application angle of graphitic carbon nitride theoretically as well as experimentally. (C) 2017 Elsevier Ltd. All rights reserved.
Vanadium dioxide (VO2) nanoparticles with reversible semiconductor-metal phase transition holds the tremendous potential as a thermochromic material for the energy-saving smart glazing. However, the trade-off between improving the luminous transmittance (T-lum) while sacrificing the solar modulation ability (Delta T-sol) hampers its bench-to-market translation. Previous studies of anti-reflection coatings (ARCs) focused primarily on increasing Tlum while neglecting DTsol, which is a key energy-saving determinant. The intrinsically low Delta T-sol (< 16%) is due to the fact that VO2 has a higher refractive index (RI) from 500 nm to 2200 nm wavelength (lambda) below its critical transition temperature (tau(c)), which causes excessive reflection at a lower temperature. This study aims to investigate ARCs with tunable RI (1.47-1.92 at lambda = 550 nm) to improve the antireflection effect at a lower temperature, thereby maximizing Delta T-sol for various VO2 nanosubstrates, e.g. continuous thin films, nanocomposites, and periodic micro-patterning films. We showed that the best performing coatings could maximize Delta T-sol (from 15.7% to 18.9%) and increase T-lum(avg) (from 39% to 44%) simultaneously, which surpasses the current benchmark specifications ever reported for ARC-coated VO2 smart glazing. In addition, the cytotoxicity analyses evidence that ARCs are feasible to improve the cyto-compatibility of VO2 nanoparticles-based nanocomposites. The presented RI-tunable ARC, which circumvents the complex materials selection and optical design, not only paves the way for practical applications of VO2-based smart windows but also has extensive applications in the field of solar cells, optical lenses, smart display, etc. (C) 2017 Elsevier B.V. All rights reserved.