Key Engineering Materials Vols. 562-565

Abstract: To get the detailed information of single cells and screen drugs effectively, especially to develop anti-cancer drugs in view of the cellular heterogeneity of tumors, biochips on single-cell level are necessary. Based on the fabrication techniques of MEMS, substrates with areas of hydrophilicity and hydrophobicity were fabricated to pattern single cells. The optimal process parameters for substrates fabrication are obtained through a series of experiments. MEMS substrates with clear binary surface patterns of hydrophilicity and hydrophobicity are achieved and a general streptavidin template with high bio-compatibility was prepared. In the experiment, biotin-BSA was employed as adhesive proteins Followed by streptavidin and biotinylated antibodies. An array of single HL-60 (Human Promyelocytic Leukemia Cells，HL-60) cells was obtained based on above protein adsorption substrate. The factors affecting the result of the single-cells patterning were investigated and optimized, by which a relatively high patterning rate is achieved. To keep cells characteristics and also for the future parallel patterning of different cells, specific antibodies are investigated for the cell HL-60, including CD45 and CD15. The result of antibodies immobilization and patterning are presented, which can well match the designed template.

Abstract: This work presents a novel analytical model for designing resonator-based MEMS filters, which eliminate the computing error caused by material parameters and generates more reliable theoretical model. This model is comfired by a composite-array filter in the work. Furthermore, this model can be applied for MEMS filters formed by any type of resonators, the geometries of the mechanical coupling beams are determined with high precision.

Abstract: The effects of different surface treatments on tribological and electrochemical properties of cast pure titanium were investigated. In this study two different surface treatments were performed which were TiN film deposition by arc ion plating, duplex treatment of plasma nitriding and TiN film deposition. Both surface treatment improved tribological and corrosion behavior of cast titanium. The duplex treated specimens exhibited higher surface hardness, better wear and corrosion resistance compared with TiN film deposited ones. All these results indicate that plasma nitriding and TiN film deposition duplex treatment can improve surface characteristics of cast titanium significantly.

Abstract: The surface microtopographies of the sea star Luidia quinaria were investigated and measured by 3D video microscope and scanning electron microscope. The antifouling effectiveness of biomimetic microtopographies based on sea star surface was evaluated using diatoms.

Abstract: To understand the capture of charged polymer in salt solution, we investigated the effect of the temperature, concentration of DNA molecules and electrical field to the polynucleotide capture rate by using a single graphene nanopore. From the result of the molecular dynamics simulations, it suggested that the capture rate becomes higher with increasing temperature and that it increases exponentially with the electrical field, and that low and high concentration of the polymer do not exhibit optimal capture rate. By analyzing the simulations results we predict that the capture rate is related to the aperture and the structure of the pore.

Abstract: This paper describes the fabrication, characterization and application of an environment-friendly tin film/gold nanoparticles (Sn/AuNPs) modified gold microelectrode for square wave stripping voltammetric (SWSV) determination of copper, lead and zinc. The microelectrode chips were fabricated by Micro Electro-Mechanical System (MEMS) technique. The sensitivity of the modified microelectrode was largely improved due to the large surface area of AuNPs and the formation of alloys between target metals and Sn. The influence of hydrogen overflow was reduced and the current response was enhanced because AuNPs made the stripping potential shift positively and Sn extended the stripping potential range. Combining AuNPs with Sn, the obtained microelectrode exhibited satisfied linearity ranges from 5 to 500 μg L-1 for copper and lead, from 10 to 500 μg L-1 for zinc, with a limit of detection of 2 μg L-1 for copper, 3 μg L-1 for lead and 5 μg L-1 for zinc. The Sn/AuNPs/gold microelectrode was successfully applied for simultaneous detection of copper, lead and zinc in tap water sample.

Abstract: In this paper, molecular dynamics method was used in researching the adsorption between single crystal aluminum and water, we built a molecular dynamics model of single crystal aluminum and water, researched the adsorption state of water on the surface of single crystal metal aluminum after nanofabrication, and gained the simulation value of the surface contact angle between aluminum and water. We also studied the impact of different orientations, different surface nanostructures, and different system temperatures on the surface contact angle. The simulation results show that: for single crystal aluminum of [10 crystal plane and water, when happen adsorption, the contact angle is approximately 61.5°, the same with the measured results; and for [11 single crystal aluminum, the contact angle is approximately 70.5 °, so different arrangement of crystal orientation has affect on surface contact angle, but does not change the hydrophilic nature. When the trench depth of the aluminum crystal surface increases, the surface contact angle is gradually increasing; and when the temperature rises, the surface contact angle increases to a certain extent.

Abstract: We have shown that various Zinc porphyrin-based nanostructures can be easily synthesized by a surfactant-assisted self-assembly method, where nonionic, anionic and cationic surfactants are employed. It was found that tuning the type of surfactant offered an alternative to promote the formation of Zinc porphyrin nanostructure with different morphologies in aqueous solutions. As-prepared nano-scale self-assemblies, including disc-shaped, ellipsoid, square and quadrangular pyramidal nanoparticles, were investigated in solution via UV/vis, fluorescence spectroscopy and SEM microscopy. The different UV/vis as well as fluorescent spectra between nano-porphyrin and its monomer further conformed that the nano-crystallization of porphyrin would result in novel optical properties differing from the single subunits.

Abstract: In this paper, two newly explored TiO₂ photocatalyst sensitized with commercial stable pigment (BYH3G and PR254) were prepared and characterized by FT–IR, UV–Vis, XRD and N₂ adsorption-desorption isotherms. The adsorption capacities and the photocatalytic activities of as-prepared photocatalysts were evaluated by photocatalytic degradation of Methyl Orange and Rhodamine B under visible light irradiation. The as-prepared photocatalysts displayed high visible light photocatalytic activity than pure TiO₂ under the same conditions. The photocatalytic activity can be reproduced commendably demonstrates that the as-prepared photocatalysts are stable and renewable, which are potentially important properties in the application of industrial wastewater treatment.

Abstract: Objective: To prepare and characterize the PEI-Fe3O4 nanosized magnetic complex and investigate the therapeutic effects of the PEI-Fe3O4 /survivin-siRNA magnetic complex combined with magnetic fluid hyperthermia (MFH) on human lung carcinoma cells . Methods: Fe3O4 magnetic nanoparticles (MNPs) were prepared by the technique of chemical co-precipitation and the surface of Fe3O4 MNPs was modified by PEI. Transmission electron microscope(TEM)，X-ray diffraction(XRD)and Fourier transform infrared spectroscopy(FTIR) were applied to characterize the PEI-Fe3O4 magnetic complex. Thermodynamic test was used to observe temperature change of various concentration of Fe3O4 suspension under alternating magnetic field(AMF). The DNA binding efficiency of PEI-Fe3O4 was observrd by electrophoresis experiment. Transfection efficiency was determined by delivering reporter gene(pEGFP-encoding luciferase)to GLC-82 cell lines using PEI-Fe3O4 as a vector. Inhibitory effect of the expression of survivin mRNA in GLC-82 cells was detected by RT-PCR after transfection with PEI-Fe3O4/survivin-siRNA. The therapeutic effects of PEI-Fe3O4/survivin-siRNA combined with MFH on GLC-82 cells was evaluated by MTT test. Results: The prepared Fe3O4 MNPs and PEI-Fe3O4 magnetic complex were approximately spherical，high electron dense，good dispersibility uniform in size observed by TEM, with an average diameter of about 20 nm.The XRD pattern of the sample showed the characteristic peaks of their cubic spinel structure,The observed diffraction lines were found to correspond to those of a standard ferrite(Fe3O4) pattern. The results of FTIR demonstrated the adsorption effect of PEI. The corresponding suspension with different concentrations of Fe3O4 MNPs could rise to a steady temperature ranging from 42°C～59°C under AMF within 40 minutes and keep stable from then on. The PEI-Fe3O4 magnetic complex had good binding ability with DNA which could efficiently deliver the foreign gene to GLC-82 cell.Inhibitory ratio of survivin mRNA expressions by survivin-siRNA was 35.6%and MTT test assay showed that the cell growth inhibition rate(IR) of the combination therapy(58.71%) is higher than that(31.87%,28.45%) of the single therapy. Conclusion: The experiment results suggested that PEI-Fe3O4 magnetic complex was an novel non-virus gene vector, which has multiple benefits in combination of thermotherapy and gene therapy on lung carcinoma.