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.
This paper focus on defining a research question while conducting action research among third-year students attending a course on Research Literacy at a teacher education college. This paper discusses the process of preparing for and conducting action research among third-year students attending a course on Research Literacy at a teacher education college. The students were asked to conduct an action research on their classroom activities. The aim of this article is to present the process and pinpointing the discomfort of the students in formulating a research question suited to action research thanks to two prerequisite conditions: the `safe space' and the `tender spot'. The research findings illustrate that the students had difficulty defining their ` tender spot'. It was necessary to create a `safe space'. Furthermore, the findings show that the `tender spot' issues were associated with disciplinary content far more than with generic lesson management or classroom management issues. The approach discussed here is leading to positive change and it may be that this professional development tool can facilitate the induction of novice teachers everywhere.
An appealing alternative approach to the conventional electro-chemical deposition is presented, which can be universally utilized to form nanomaterial coatings from their aqueous dispersions without involving their oxidation-reduction. It is based on altering the ionic strength by electrical potential in the vicinity of the electrode surface, which causes the nanomaterials to deposit. The concept has been demonstrated for four different systems.
We report the first attempt of using molecularly imprinted polymers (MIPs) in the shape of nanoparticles that were doped with gold nanoparticles (AuNPs) for surface enhanced Raman scattering (SERS)-based sensing of molecular species. Specifically, AuNPs doped molecularly imprinted nano-spheres (AuNPs@nanoMIPs) were synthesized by one-pot precipitation polymerization using Sudan IV as the template for the SERS sensing. The AuNPs@nanoMIPs were characterized by various modes of scanning transmission electron microscopy (STEM) that showed the exact location of the AuNPs inside the MIP particles. The effects of Au concentration and solution stirring on the shape and the polydispersity of the particles were studied. Significant enhancement of the Raman signals was observed only when the MIP particles were doped with the AuNPs. The SERS signal improved significantly with increase in the Au concentration inside the AuNPs@nanoMIPs. Selectivity measurements of the Sudan IV imprinted AuNPs@nanoMIPs carried out with different Sudan derivatives showed high selectivity of the AuNPs-doped MIP particles.
Calcium phosphate (CaP) ceramics have been prevalently used as coatings for implants because of their excellent osteoconductive and bioactive properties. Yet, bone regeneration procedures might have complications such as bacterial infection, local inflammation, bone destruction, and impaired bone healing. Here, we present a novel in situ electrodeposition of CaP with chitosan nanoparticles containing antibiotics. The deposition was shown to be fast and efficient. The deposited layer of octacalcium phosphate (OCP) and monotite contained a large amount of gentamicin, which was released gradually over a period of 15 days. These phases may be beneficial for bone growth, as OCP has higher solubility than the stoichiometric hydroxyapatite (HAp) and is commonly considered as a precursor to HAp, while monotite has even faster resorbability. In addition, both the cytotoxicity and biomineralization of the coating were studied, and the coating was proven to be noncytotoxic and highly biomimetic.