Solid State Phenomena Vols. 121-123

Abstract: Amphiphilic hyperbranched polyamidoamine (PAMAM) and poly(sulfone-amine) (HPSA) were prepared and their dye-encapsulation properties were investigated. Both of them can carry water-soluble dyes from aqueous solution into chloroform. The selectivity of host to guests and the influence of interaction between different dyes on loading capacity were also investigated by performing comparable experiments. Encapsulation capacities are considered to have relationship with the water-solubility of the hyperbranched polymer core, the polarity difference between the hydrophilic core and the hydrophobic shell, the molecular structure of dyes, and the interactions between dyes.

Abstract: Microcontact printing (μCP) is a newly developed bioresearch technique applied in many fields such as absorption of proteins, adjunction and growth of cells and so forth, because of the controllable structure of its patterned materials. Further experiments showed that the microcontact printed proteins and cells can keep their bioactivity, which provides a feasibility of bio-molecule or cell analysis. The self-assembled molecules of μCP make molecule-scaled reactions possible, which have much higher accuracy compared with large amount reactions in solutions. In this article we first modified the chemical treated slide with APTES (3-aminopropyltriethoxysilane) to form AP-glass substrate, then with GA (glutaraldehyde) to form a GA-AP-glass substrate, and at last used XPS (X-ray Photoelectron Spectroscopy) technique to show the chemical structure changes of the surface molecules. Next, using μCP，we patterned chicken IgG (Ag1) and rabbit IgG (Ag2) onto the GA-APTES-glass substrate in vertical directions. After incubating the substrate with BSA (bovine serum albumin, a kind of protein) to block the blank place, we exposed the substrate to Anti-Chicken-IgG-FITC (Ab1) and Anti-Rabbit-IgG-TRITC (Ab2). Because of the specific binding between Ab and Ag, through fluorescence microscopy we could see the two-colored fluorescence images on the GA-AP-glass substrate, in which the different colored strands were vertical patterned.

Abstract: We developed a simple method for the tensile properties of electrospun nanofibers by using a computerized spring-balance/step-motor setup. Calculation of total cross-sectional areas for each sample with vertically aligned nanofibers was readily done by SEM images and optical micrograph. The detailed setup and feasibility were described in the text. The tensile stress-strain curves of carbon nanotube incorporated polystyrene nanofibers were determined through this method, and characteristically consistent data, which was collected from each different sample, were successfully obtained.

Abstract: Molecular assembly technology has attracted much research attention due to its flexible applications in modulation of surface property and construction of nanostructures and devices. Herein, a well-defined surface metallization technique has been achieved via anchoring electroless catalysts onto substrates’ surfaces with the pendant active groups of self-assembled monolayers. This method affords a means to control surface functionality at molecular level and has advantages over the conventional Sn-Pd methods, such as convenient operation, good reproducibility, increased longevity of the activated initiator and improved adhesion of metal deposition to substrates. Therefore, it has great significance in the fields of developing bottom-up combined micro/nano-fabrication technique. This metallization process has been successfully performed on hollow ceramic particles to fabricate light-weighted core-shell functional materials.

Abstract: Iron oxide and its hydrate nanoparticles were synthesized by hydrothermal method and confirmed by infrared and SEM (Scanning Electron Microscope) et al. The dimensions of the nanoparticles are about 50-120 nm. The crystalline form of iron oxide nanoparticles is like globosity while its hydrate rod. Amino acids intermingling with the synthesized nanoparticles were crystallized to investigate the space effect of the nanoparticles. The crystalline forms of crystal are different to that of pure amino acid. The positions and width of the nanoparticles’ peaks in the infrared spectrum are changed too. Microscope observation and infrared spectrum results indicated the nanoparticles had changed the internal structure of amino acids crystal. To considerate the toxicity of the synthesized nanoparticles, MTT (3-(4,5-dimethylthiazol 2-yl)-2,5 diphenyltetrazolium bromide) assay was used to determine their cytotoxicity. The OD value (Optical Density) was used to calculated RGR% (Relative Generation Rate) of cells, which determined the grade of cytotoxicity. The RGR of nanoparticles of iron oxide and its hydrate are about 1 to 2, which indicate they have just low toxicity.

Abstract: Weng`an fauna in Guizhou, China provides a unique window for the evolution of the early life especially since the animal embryos and sponge is found there. Phosphatization makes the fossils preserve in details including cells and subcellular structure. Here we use atomic force microscope observing the surface of some three dimensional preserved embryo fossils and the ultra membrane-like structure is found under atomic force microscope (AFM) while such structure can`t be found under scanning electron microscope (SEM). The membrane-like structure is approximately 10nm in thickness which maybe one part of the fossil embryos or belong to another nano scale microfossils. Therefore, AFM provides a new method for the study of the ultra structure of the microfossils from Weng`an fauna.

Abstract: Nanoscale magnetic materials have been receiving increasing interest for their potential applications. One-dimensional magnetic particles chain of polycrystalline nickel was prepared by a simple template-free method under magnetic field. Based on solution reduction reaction of Ni2+, metallic nickel was deposited and synchronously self-assembled into chains under magnetic field. The results show that the chain of polycrystalline nickel was several micrometer in length and several hundreds nanometer in diameter. VSM measurements indicate the magnetic properties of chains formed can be modulated by the reaction time and the solution concentration. It is suggested that the magnetic field be an effective and tunable way to the fabrication one-dimensional chains of magnetic materials.

Abstract: Amino-modified tetrapod-like ZnO nanostructures were tried as novel carriers for mammalian cell transfections. The nanostructures consisted of four needle-shaped tetrahedrally arranged legs connected at the center. After silica coating and amino modification, ZnO nanostructures complexes bound plasmid DNA through electrostatic interactions in aqueous solution. When mixed with cells, DNA-nanostructures attached easily onto cell membranes and entered the cells for gene expressions. Due to high positive charge densities on surfaces and needle-shaped tetrahedral structures, functionalized ZnO used as carriers for cell transfections with both high transfection efficiency and little cytotoxicity. And a possible transfection machamism was proposed in this report.

Abstract: The purpose of this study was to prepare chitosan nanoparticles (CS NP) for controlled protein delivery. Two techniques, simple ionotropic gelation (method [I]) and w/o/w emulsion solvent evaporation containing ionotropic gelation (method [II]), were used to prepare CS NP. Tripolyphosphate (TPP) and Eudragit L100-55 (Eud) were used as anionic agents to form complex with cationic chitosan. Bovine serum albumin (BSA) was encapsulated into NP. The morphological characteristics, particle size and size distribution, protein entrapment efficiency, zeta potential, in vitro release, protein secondary structure and its integrity were investigated. The results showed that CS NP could be prepared by appropriate cationic and anionic ratios in both methods. Excess anionic agents resulted in particle aggregation of micron size. The median sizes of particles were between 0.127-0.273 mcm with method [I] provided the smallest size. The 0.02-0.10% BSA loaded preparations showed the same particle sizes and size distributions as blank preparations. SEM photomicrographs revealed that the obtained NP were spherical. Protein entrapment efficiency was between 47-84% and increased when decreasing the percentage of drug loading. The method [II] with TPP exhibited the highest protein entrapment efficiency, following by the method [II] with Eud and method [I] with TPP, respectively. The zeta potentials were positive. Prolonged in vitro protein release profiles were observed from all preparations of CS NP. After 10 days, the release was between 53-72%. Circular dichroism and SDS-polyaceylamide gel electrophoresis techniques confirmed that these processes did not have any destructive effect on the protein structure. Therefore these preparation techniques could be used to encapsulate water-soluble drugs, proteins, DNA, or antigens into CS NP as effective delivery carriers.

Abstract: A dumbbell-liked organ-metal composite was prepared with wet chemistry. Then the solution was subjected to AC e-field. Herein, three types of electrodes configuration were adopted to align the colloids. Theoretically, quasi one-dimensional structures should be observed, and it was the case in the third configuration. SEM, AFM and TEM were utilized to characterize the resultant morphology. The mechanism was described with dielectrophoresis theory.