Molecular Deposition Technique Research Articles

Thermally Controlled Bonding of Adenine to Cerium Oxide: Effect of Substrate Stoichiometry, Morphology, Composition, and Molecular Deposition Technique

The adsorption of adenine, one of the structural units of DNA and RNA, on nanostructured cerium oxide was studied using synchrotron radiation based techniques: photoelectron and X-ray absorption spectroscopies. Using a systematic approach, we studied this biomolecule’s bonding to the inorganic surface and examined the effects of different stoichiometry, morphology and composition of cerium oxide films, as well as two methods of molecular deposition (evaporation in vacuum and deposition from aqueous solution). The adenine molecule chemisorbs on the stoichiometric (IV) cerium oxide intact via nitrogen atoms, independent of the oxide morphology and deposition technique. Annealing of the adenine adlayer at 250 °C causes CeO2 surface partial reduction, along with the partial deprotonation of the nitrogen. The reaction of adenine with ex situ prepared CeO2 films (nanostructured compact and porous) activates Ce4+ cation reduction not only on the surface but also in the subsurface layers accompanied by water deso...

Photochromic Inorganic/Organic Self-Assembled Superlattice Films

Phosphotungstic acid (PW12) and 1,10-diaminodecane (1,10-DAD) molecules have been alternatively assembled on 3-aminopropyltriethyoxysilane modified quartz or silicon substrate to form multicomposite mutilayer thin films by the molecular deposition technique. Thus-obtained films were characterized by UV-visible, XRD, X-ray reflection (XRR), and XPS spectra. Results show that the layer-by-layer self-assembly of PW12 and 1,10-DAD leads to a well-ordered superlattice-layered structure with a d-spacing of 3.19 nm, which exhibits extremely exciting photochromic properties. Based on the experimental data, a presumable interlayer structural model has also been suggested.

Coimmobilization of glucoamylase and glucose isomerase by molecular deposition technique for one-step conversion of dextrin to fructose

Glucose isomerase was immobilized by itself with adsorption and coimmobilized with glucoamylase by molecular deposition technique using macroporous trimethylamine polystyrene beads. Approximately 77.5% of the enzyme added was immobilized. The pH-activity curve of the immobilized glucose isomerase was broadened, resulting in 75% retention of its maximum activity at pH 6.2. The K m of the immobilized glucose isomerase was 1.28-fold that of the soluble one. When the two enzymes were immobilized together, the system was found capable of functioning at pH 6.0 to produce fructose from starch and dextrin. At this pH, the total fructose output of the coimmobilized enzyme system after 24 h was 1.9 times that of the free enzyme system.

Fabrication of a multilayer film electrode containing porphyrin and its application as a potentiometric sensor of iodide ion

A novel iodide ion-selective electrode has been produced based on a molecular deposition technique in which water-soluble porphyrin was alternatively deposited with water-soluble polypyrrole on a 2-aminoethanethiol modified silver electrode. The potentiometric response is independent of pH of the solution between pH 1 and 7, while it is dependent on the nature of the medium. The electrode has a linear dynamic range between 1.6×10 −6 and 0.1 M with a Nernstian slope of 59 mV/decade and a detection limit of 1.0×10 −6 M in acetate buffer (0.1 M, pH 4.6). The electrode has the advantages of low resistance, short conditioning time and fast response.

Immobilization of glucose isomerase and its application in continuous production of high fructose syrup

Bilayer glucose isomerase was immobilized in porousp-trimethylaminepolystyrene (TMPS) beads through a molecular deposition technique. Some of the factors that influence the activity of immobilized glucose isomerase were optimized, with the enzyme concentration of 308 IU/mL, enzyme-to-matrix ratio of 924 IU/g wet carrier, and hexamethylene bis(trimethylammonium iodine) concentration of 15 mg/mL giving the maximum catalytic activity (2238 IU/g dry gel) of the immobilized bilayer glucose isomerase, retaining 68.5% of the initially added activity. The half-life of the immobilized bilayer glucose isomerase was approx 45 d at pH 8.5, 60°C, with 50% (w/v) glucose as substrate. The specific productivity of the immobilized bilayer glucose isomerase was 223 g dry D-glucose/g dry immobilized enzyme per d.

Co-immobilization of cellulase and glucose isomerase by molecular deposition technique

Cellulase was immobilized and co-immobilized with glucose isomerase within p-trimethylamine polystyrene beads using a molecular deposition technique. The co-immobilized enzyme system directly converted insoluble cellulose to glucose and fructose in 60:40 molar ratio. The co-immobilized enzyme still retained 50% of its initial activity at 50°C after 4 recycles of 5 hours for each time.

Atomic probes: a search for conduction through a single molecule

We present a novel approach in an effort to perform electrical measurements at the level of a single molecule. A mechanical controllable break junction is utilized in combination with a molecular deposition technique in fluid to obtain the system: metal-molecule-metal. The I - V curve of this system shows pronounced features over a large voltage scale.

Co-immobilization of glucoamylase and glucose oxidase based on molecular deposition

Glucoamylase and glucose oxidase were co-immobilized within p-trimethylamine polystyrene beads by a molecular deposition technique. The velocity of the co-immobilized enzyme system was 4 and 2 times that of the separately immobilized and the free enzyme systems, respectively.

Electrocatalytic oxidation of carbohydrates at a molecular deposition film electrode based on water-soluble cobalt phthalocyanine and its application to flow-through detection

A novel chemically-modified electrode was achieved based on a molecular deposition technique in which water-soluble cobalt phthalocyanine tetrasulfonate (CoTsPc) was alternately deposited with a bipolar pyridine salt (PyC 6BPC 6Py) on a 3-mercaptopropionic acid-modified Au electrode. The modified electrode was shown to exhibit an electrocatalytic response for the oxidation of carbohydrates. Carbohydrates were detected by flow-injection analysis at the modified electrode with high sensitivity. Detection limits obtained in this manner range from 150 pmol injected for glucose and fructose to 600 pmol injected for maltose and sucrose.

Effect of arterial PO 2 on microheterogeneity of myocardial blood flow evaluated by a molecular deposition technique

Effect of arterial PO 2 on microheterogeneity of myocardial blood flow evaluated by a molecular deposition technique

Selective potentiometric determination of copper(II) ions by use of a molecular deposition film electrode based on water-soluble copper phthalocyanine

A novel copper(II)-selective electrode was produced based on a molecular deposition technique in which water-soluble copper phthalocyanine tetrasulfonate was alternatively deposited with a bipolar pyridine salt (PyC 6BPC 6Py) on a 3-mercaptopropionic acid modified Au electrode. The potentiometric response is independent on pH of the solution between pH 1 and 5, while it is dependent on the nature of the medium. The electrode has a linear dynamic range between 1 × 10 −5 and 0.1 mol 1 −1 with a Nernstian slope of 29 mV/decade concentration and a detection limit of 7 × 10 −6 mol 1 −1 in acetate buffer (0.2 mol 1 −1, pH 4.5). Except for Fe 2+, Fe 3+ and Co 2+, other common inorganic cations do not interfere in the determination of copper(II). The electrode has the advantages of low resistance, short conditioning time and fast response.