We developed a noble carbon nanotube (CNT) deposition method using a layer-by-layer technique, in which the deposition of a thin layer of CNTs and a CF4 plasma exposure on its surface were carried ...out alternatively. Owing to the difference in the etch rate between amorphous carbon, graphite and CNTs by CF4 plasma, we can selectively etch out some of the unwanted amorphous carbon and graphite phases from the CNTs. In addition, CF4 plasma treatment on the surface can open the ends of the deposited CNTs and results in the increase of emission currents. The new CNTs exhibited a turn-on field of 1.2 V/μm.
Surface properties of cellulosic fibers can be modified by Layer-by-Layer (LbL) technique. Cotton fibers are one of important non-wood and industrial cellulosic resources in the world. Cotton linters ...is produced as a by-product accompany with cotton fibers which is used as a significant cellulosic sources in paper industry for producing durable paper. In this research, the influence of alternate adsorption of cationic chitosan and anionic Nanosilica on modification of fiber surface of cotton linter was investigated. The adsorption of materials on cellulosic fibers was analyzed via electrolyte titration. Experiments were conducted at pH≈3-4 for formation of cationic layer and pH≈9-10 for formation of anionic layer applying stirring rate of about 750rpm, for15 minute deposition time to construct 1 to 3 layers. Hand sheets of about 60 g/ m2 basis weight were made form modified pulp fibers prepared by multilayering of chitosan and nanosilica, then their structural properties and bonding ability were evaluated. Bonding ability of fibers was improved by polyelectrolyte multilayering (PEM) on the surface of cotton linter fibers which was visualized by Field Emission Scanning Electron Microscopy (FESEM).The results showed that apparent density and also bonding ability was improved in the treated fibers because of the increased electrostatic attraction between polycation and anion sites existed on the fiber surface. Apparant density of paper was improved remarkably compared to the untreated fibers. Tensile index of the sheet was increased about 16% with consecutive adsorption onto the cotton linter fibers compared to untreated fibers. Formation index of paper was slightly deteriorated after polyelectrolytes multilayering.
We have successfully prepared the hetero-multilayered thin films composed of polydiacetylene microcrystals and gold and/or silver fine particles by means of electrostatic deposition technique, i.e., ...layer-by-layer deposition method, characterized the morphological structure of the thin films, and evaluated their optical properties.
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Deceased.
We have studied the improvement of electron emission by diamond-like carbon (DLC) coating on Mo field emitter arrays by a layer-by-layer technique using plasma enhanced chemical vapor deposition. The ...turn-on voltage was lowered from 55V to 30V by 20 nm DLC coating and maximum emission current was increased from 166μA to 831μA. Also the gate voltage required to get the anode current of 0.1 (μA/emitter) decreases from 77V to 48V. Furthermore, the emission current from DLC coated Mo FEAs is more stable than that of non-coated Mo FEAs.
Cell adhesion is a prerequisite for healing of implant materials and colonization of tissue engineering scaffolds. Hence, it is a crucial task to control adhesion of cells on biomaterials, which can ...be achieved by surface modification. Different techniques can be used to modify the surface of materials, which have the desired physical and chemical properties, but lack sufficient biocompatibility. Among the techniques of surface modification, a number of self assembly methods have the advantage to work in solutions, so that different shaped materials can be modified easily. Self assembly methods selected in this study were chemisorption and covalent binding of alkylsiloxanes on glass (i), photochemical binding of polyethylene glycol on hydrophobic polymers (ii) and alternating adsorption of polyanions and polycations to assemble nanostructured multilayers on charged surfaces (iii). These methods enable to obtain control on adhesion of cells on different classes of biomaterials, which eventually may promote subsequent processes like cell growth and differentiation.
Abstract Gradient shell cross-linked hollow polyelectrolyte nanocapsules composed of cysteamine conjugated chitosan and dextran sulfate were prepared by layer-by-layer adsorption on β-cyclodextrin ...(β-CD) functionalized silica spheres followed by cross-linking thiols and removal of silica core. This disulfide bond gradient cross-linked nanocapsules combined reduction and pH sensitive. Gradually increased from the inside to the outside of the cross-linking degree, one purpose is to ensure that cross-linking disulfide bond after reduction cleavage still has pH sensitive, on the other hand is to avoid cross-linked contraction of internal damage the crystal and bioactivity of protein drugs. Disulfide cross-linked nanocapsules were used to enhance the physical stability against acidic pH conditions compared to the un-cross-linked ones. Bovine serum albumin, as a model protein drug, was loaded inside nanocapsules. The disulfide bond cross-linked nanocapsules are intended to remain more stable in physiological pH and decrease the loss of protein drugs caused by the gastric cavity, and can release the drugs in the intracellular environment after glutathione reduction.
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