1,720,979 research outputs found
An investigation about thin films of Poly(2-methoxy-5-(2-ethyl-hexyloxy) phenylene vinylene] (MEH-PPV) prepared by Langmuir-Schaefer technique,
No full textLangmuir-Schaefer films of Nafion with incorporated TiO2 nanoparticles
No full textAn easy method of incorporating TiO2 nanoparticles into Nafion perfluorinated ionomer is proposed. Ultrathin films of Nafion were prepared by employing the Langmuir-Schaefer (LS) technique. The pressure-area isotherm study of a Langmuir monolayer of Nafion at the air-water interface on different concentrations of NaCl as the subphase allowed us to find the best experimental conditions for the deposition of stable Langmuir-Schaefer films. Incorporation of TiO2 nanoparticles was performed by dipping Nafion LS films in a solution of TiO2 nanoparticles. The uniformity of the TiO2 incorporation was detected by UV-visible spectroscopy. The morphology of the Nafion, Nafion/TiO2 nanoparticles thin films, and the changes due to the annealing procedure were investigated by atomic force microscopy. Interestingly, the AFM investigation showed that Nafion and Nafion/TiO2 LS films have thermal stability up to 600°
Functionalization and photoelectrochemical characterization of Poly[3-3(vinylcarbazole)]-Multi-Walled Carbon Nanotubes (PVK-MWNTs) Langmuir-Schaefer Films
No full textMulti-walled carbon nanotubes (MWNTs) were functionalized via oxidative polymerization of 3-3_(vinylcarbazole) (PVK). Thin films of PVK-functionalized MWNTs (PVK-MWNTs) were fabricated by the LangmuirSchaefer (LS) technique and characterized by spectroscopic, microscopic, electrical and electrochemical techniques before and after doping with iodine. I/V characterization showed an increase in the conductivity of the PVK-MWNTs and I2-doped PVK-MWNTs compared with the PVK and I2-doped PVK, respectively. The electrochemical characterization showed the formation of an I2-doped PVK-MWNT complex. These nanostructured PVK-MWNT films revealed an increase in the current density under illumination of about 500 nA cm−2
Synthesis, fabrication and characterizatoin of poly[3-3'(vinylcarbazole)] (PVK) Langmuir-Schaefer films
No full textPoly[3-3’(vinylcarbazole)] (PVK) was synthetized with N-vinylcarbazole as monomer by oxidative polymerization with ferric chloride. The resulting polymer was then deposited on various solid supports by using Langmuir–Schaefer (LS) method. The pressure–area isotherm of PVK revealed the possibility of compact monolayer formation at air–water interface. Different layers of PVK were doped with iodine vapours. Both scanning probe microscopy and optical microscopy images indicated a good uniformity of the films. The morphology and the thickness of PVK films were investigated using atomic force microscopy. The voltammetric investigation of I2 doped PVK showed a distinctive electrochemical behaviour. The photoinduced charge transfer across a donor/acceptor (D/A) hybrid interface provided an effective method to study the photoelectrochemical properties of the composite LS films
Functionalization and photoelectrochemical characterization of poly[3-3'(vinylcarbazole)] multi-walled carbon nanotube (PVK-MWNT) Langmuir–Schaefer films
No full textEnzymes Encapsulated within Alginate Hydrogels: Bioelectrocatalysis and Electrochemiluminescence Applications
No full textA simple procedure to incorporate enzymes (horseradish peroxidase, HRP, and lactate oxidase, LOx) within alginate hydrogels is reported with electrochemiluminescence (ECL) used to detect the enzymatic reactions with the corresponding substrates. First, HRP and LOx were successfully immobilized into CaCO3 microspheres, followed by the electrostatic layer-by-layer deposition of a nanoshell onto the microspheres, and finally by their dispersion into alginate solution. The as-prepared dispersion was drop cast onto the glassy carbon electrodes and cross-linked by the external and internal gelation methods using Ca2+ cations. The enzymes encapsulated within the alginate hydrogels were characterized using cyclic voltammetry and kinetic studies performed using ECL. The results showed that the enzymatic activity was significantly maintained as a result of the immobilization, with values of the apparent Michaelis-Menten constants estimated as 7.71 ± 0.62 and 8.41 ± 0.43 μM, for HRP and LOx, respectively. The proposed biosensors showed good stability and repeatability with an estimated limit of detection of 5.38 ± 0.05 and 0.50 ± 0.03 μM for hydrogen peroxide and lactic acid, respectively. The as-prepared enzymes encapsulated within the alginate hydrogels showed good stability up to 28 days from their preparation. The sensitivity and selectivity of the enzymes encapsulated within the alginate hydrogels were tested in real matrices (HRP, hydrogen peroxide, in contact lens solution; LOx, lactic acid in artificial sweat) showing the sensitivity of the ECL detection methods for the detection of hydrogen peroxide and lactic acid in real samples
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