Papers by Keyword: Surface Nanostructure

Abstract: The micro-structure of the surface of Hevea brasiliensis latex particles has been found by the means of atomic force microscopy (AFM), confocal laser scanning microscopy (CLSM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), cryogenic transmission electron microscopy (cryo-TEM), and electrokinetics over a broad range of KNO₃ electrolyte concentrations (4-300 mM) and pH values (1-8). Based on the atomic force microscopy analysis of the fresh natural rubber latex, it could be estimated that the protein-lipid layer is covered with the rubber particles. The molecules in the particle were labeled with fluorescent Rhodamine (RB), and were monitored by CLSM. SEM and TEM were used to observe the surface of fresh natural rubber particles and were dyed by osmium tetroxide. Fourier Transform Infrared Spectroscopy (FTIR) has been used to characterize the nitrogenous groups in natural rubber and deproteinized natural rubber (DPNR). The FTIR and ¹H-NMR analysis of phosphatase-treated DPNR confirmed that the presence of mono- and diphosphate terminations without phospholipids was also unlikely owing to the presence of a methylene proton signal of an isoprene unit linked to mono- and diphosphate groups. The , [η] and Higgins’ k’ of DPNR decreased after being treated with lipase.

Abstract: The investigation was carried out to study the effect of a novel process of surface modification, surface nanocrystallization by high energy shot peening (HESP), on osteoblast proliferation and differentiation. A disc of pure titanium was processed to HESP in a commercial shot peening equipment, to create nanostructure at the surface. The surface microstructure was characterized by SEM and osteoblasts were co-cultured with the surface nanostructured titanium and unreceived titanium surface to evaluate their biocompatibility. The nanostructured surface layer on titanium was successfully processed by HESP, and the nanosized grains were about 60 nm in diameter and inhomogeneous distributed on the surface of n-Ti. The results also confirmed the proliferation and differentiation of osteoblasts were highly improved on surface nanostructured titanium. This finding suggests that there is high potential of this novel surface modification process which could enhance bone tissue growth of dental implant.

Abstract: The fabrication of large area nanoscale periodic structures on material surfaces for hydrophobicity engineering has been difficult due to the complex processes. Here we propose a two-step fabrication method for periodic nanostructures by combining laser interference lithography (LIL) and reactive ion etching (RIE). Sub-micron periodic nanotip patterns are fabricated in the photoresist by LIL, and then transferred into the silicon substrate using RIE. By measuring the contact angle (CA) of a water droplet on the substrate surface, the wettability of the surface with nanotip structures of various periods is studied. Our experiments show that the nanotip structures fabricated by the combined LIL and RIE process deliver satisfactory hydrophobic tendencies when the periods fall into the submicron scale. When the period of the structure is small enough, the hydrophilicity of the surface can be altered into hydrophobicity. The hydrophobicity achieved by this method is reusable and sustainable with low cost and no composition alteration comparing to chemical methods. The process developed in this work provides potential applications in biosensingand digital fluidics.

Abstract: Titanium with surface nanostructure has superior mechanical and biological properties, which benefits titanium implants. To further improve the bioactivity of Ti surfaces, Ca/P-containing porous titania coatings were prepared on Ti with surface nanostructure by ultrasonic shot peening (USP) and micro-arc oxidation (MAO). The phase identification, composition, morphology and microstructure of the coatings of Ti with surface nanostructure during MAO were investigated subsequently. The amounts of Ca, P and the Ca/P ratio of the coatings formed on Ti with surface nanostructure were greater than those on coarse-grained Ti. Incubated in a simulated body fluid, bone-like apatite was completely formed on the surface of Ti, thus evidencing preferable bioactivity.

Abstract: A new approach to obtain Si nanostructures on insulating layer is proposed by laser irradiation on ultra-thin hydrogenated amorphous silicon (a-Si:H) films with subsequently thermal annealing. It was found that the surface nanostructuring was occurred when the laser fluence exceeded the threshold value as revealed by AFM images. The size and area density of formed Si nanostructures were depended on the laser fluence and film thickness while thermal annealing played an important role in the size and its distribution. The results showed that a high density (>1011cm-2) Si nanostructures with average lateral size of 10-20nm can be achieved by the present technology.