No abstract

Au nanoparticles modified with 21-base thiolated-oligonucleotides have been evaluated as delivery vehicles for the development of a nonviral transfection platform. The electromigration combined with electroporation for DNA delivery in an osteoblast like cell was employed to test on microchips. Electroporation introduces foreign materials into cells by applying impulses of electric field to induce multiple transient pores on the cell membrane through dielectric breakdown of the cell membrane. On the basis of the characteristic surface plasmon of the Au particles, UV-vis absorption was utilized to qualitatively judge the efficiency of delivery. Transmission electron microscopy images and atomic absorption measurements (quantitative analysis) provided evidence of the bare Au and Au/oligonucleotide nanoparticles before and after electroporation and electromigration function. The experiments demonstrated that electrophoretic migration followed by electroporation significantly enhanced the transportation efficiency of the nanoparticle-oligonucleotide complexes as compared with electroporation alone. Most interestingly, Au capped with oligonucleotides led to optimal performance. On the other hand, the bare Au colloidal suspensions resulted in aggregation, which might be an obstacle to the internalization process. In addition, analytical results demonstrated an increase in the local particle concentrations on the cell surface that provided additional support for the mechanism underlying the improved Au nanoparticle transportation into cells in the presence of electromigration function.

The paper proposed novel designs to pinch the transverse diffusion of the sample in the injection mode using microelectrodes to generate the potential difference at the channel intersection in the capillary electrophoresis (CE) microchip. A pair of microelectrodes was used to conduct the injection channel and the separation channel, which directly provided the potential to pinch the sample without using a power supply. These new designs of the CE microchip simplify the electric circuitry and improve performance. Simulations were performed using the CFD-ACE[trade mark sign] software. The mechanisms of diffusion and electrophoresis were employed in the numerical simulation. The injection and separation processes of the sample were simulated and the parameters of the present design were investigated numerically.

Powder X-ray diffraction (XRD) is one of the primary techniques used to characterize solid state materials. But there is not a sample holder which can be fit into the sample carrier of the Bruker D8-Advance x-ray powder diffractometer for flakiness and block samples test. In this article, we will design, manufacture and evaluate a sample holder for flakiness and block samples. Materials of the holder are steel, glass and plasticine etc. The holder is low cost, easy to be processed, convenience to prepare the samples, and accurately obtain the best analytical results.