An innovative heterojunction is fabricated between two sides of afreestanding thin film of HCl-doped polyaniline (PANI) derivativecontaining azobenzene side-chain, which is synthesized through anN-alkyl-substituted reaction. Of the film, the side with beingirradiated by UV light during preparation is represented as `Aside'; the other side without being irradiated is represented as`N side'. The electrical properties of the heterojunction aremeasured and the rectifying effect is observed in the{current--voltage} characteristic curves with the values ofrectifying ratio (γ) being 20 at ±0.06 V at T= 77Kand 4 at ±0.02V at T=300 K separately. 相似文献
Hepatitis B virus core antigen (HBcAg) gene (C gene) was expressed in Saccharomyces cerevisiae and the products (rHBcAg or core particles) were purified from a crude lysate of the yeast by three steps: Sephrose CL-4B chromatography, Sucrose step-gradient ultracentrifugation and CsCl-isopycnic ultracentrifugation. It has been observed that HBcAg was synthesized in yeast cells as a particle consisting of polypeptides with a molecular weight of 21.5 kDa (p21.5). Results of ELISA test and density analysis of CsCl-isopycnic ultracentrifugation indicated that the purified products (rHBcAg particles) with HBcAg antigenicity mainly located at the densities of 1.27 and 1.40 g ml(-1), respectively. Observation and analysis of the purified rHBcAg products by TEM indicated that rHBcAg peptides could mainly self-assemble into two size classes of core particles. The larger particles were approximately 30.1 nm and the smaller were approximately 21.5 nm in mean diameter. Further observation and analysis of the same rHBcAg (core) particles by AFM also indicated that rHBcAg (core) particles were similar to the native HBcAg (core) particles from infected human hepatocytes and mainly composed of two size classes of partides core. The larger particles were approximately 31.3 nm and the smaller were approximately 22.5 nm in mean diameter which was similar to the results obtained by TEM. All results from both TEM and AFM suggested that core particles (capsids) produced in S. cerevisiae possessed dimorphism. 相似文献
Periodic measurements of positron lifetime and X-ray line broadening were made at various times during the plastic fatigue cycling of pure Ni and Ni–66.5% Co alloy. Observations of the sub-structure at fracture were made by transmission electron microscopy. The positron lifetime increases rapidly during the early part of the fatigue life and remains almost constant thereafter. The mean positron lifetime changes from about 140 to about 230 ps during fatigue. This early saturation of positron lifetime far precedes the saturation of the change in X-ray particle size. 相似文献
Mononuclear [Ce(pztza)2(H2O)6](pztza)·H2O (1) (pztza = 5-(2-pyrazinyl)tetrazole-2-acetato) has been prepared and characterized by IR, elemental analysis and single-crystal X-ray diffraction. PEG-5000 (poly(ethyleneglycol-5000)) coated [Ce(pztza)2(H2O)6](pztza)·H2O nanoparticles (NPs) can disperse into distilled water. In vitro study on Hela cells shows that Hpztza is nontoxic while [Ce(pztza)2(H2O)6](pztza)·H2O NPs show high toxicity with half-maximal inhibitory concentration (IC50) of 17 μg/mL (1.93 × 10?5 M). In addition, such NPs can inhibit the migration of Hela cells effectively. 相似文献
A study is presented on the binding kinetics and mechanism of the adsorption of dsDNA on citrate-capped gold nanoparticles (AuNPs). Methods include fluorescence titration, isothermal calorimetry (ITC) titration, dynamic light scattering and gel electrophoresis. It is found that the fluorescence of probe DNA (labeled with Rhodamine Green and measured at excitation/emission peaks of 498/531 nm) is quenched by addition of AuNPs. The Stern-Volmer quenching constant (Ksv) is 1.67?×?10^9 L·mol?1 at 308 K and drops with increasing temperature. The quenching mechanism is mainly static. The results of both fluorescence titrations and ITC show negative values for ΔH and ΔS values. This shows ion-induced dipole-dipole interaction to be the main attractive forces between dsDNA and AuNPs, while electrostatic interactions result in repulsion. The repulsive forces lead to a lower affinity between dsDNA and AuNPs (compared to single-strand DNA). It is also found that dsDNA can prevent the aggregation of AuNPs which is accompanied by a color change from red into blue. The visual detection limit with bare eyes for dsDNA1 is 36 pM. Based on these findings, a colorimetric method was developed to detect the proto-oncogene of serine/threonine-protein kinase B-Raf V600E point mutation in HT29, Ec109, A549, Huh-7 and SW480 cell lines.
Graphical abstract Schematic of the salt-induced aggregation of uncapped gold nanoparticles (AuNPs) which leads to a color change from red to blue. If the AuNPs are coated with dsDNA, aggregation is suppressed.
