ABSTRACT. Monomethoxypolyethylene glycol-chitosan (mPEG-CS) nanoparticles were used as interfering RNA carriers to transfect human prostate cancer PC-3M cells to evaluate the effects of livin and survivin gene silencing on the proliferation and apoptosis. mPEG-CS nanoparticles with sizes of approximately 60 nm were first synthesized by ionic crosslinking. Through electrostatic adsorption, mPEG-CS-livin short hairpin RNA (shRNA), mPEG-CS-survivin shRNA, and mPEG-CS-(livin shRNA + survivin shRNA) nanoparticles were then prepared to transfect PC-3M cells. The mRNA and protein expression levels of livin and survivin were measured by reverse transcription-PCR and western blotting, respectively. The inhibitory effects of down-regulated livin and survivin gene expression on the cell proliferation were evaluated by MTT assay. Cell apoptosis was assessed visually using Hoechst staining. Livin and survivin expression levels in all shRNA interference groups were effectively down-regulated at both the mRNA and protein levels. Dual silencing of livin and survivin genes markedly inhibited cell proliferation and facilitated apoptosis, with better outcomes than those of individual shRNA treatments. mPEG-CS nanoparticle-mediated dual shRNA interference of livin and survivin genes significantly reduced the expression levels in PC-3M cells, inhibited proliferation, and promoted apoptosis. As these effects were superior to single interference, this method may have synergistic effects.
A large quantity of uniform ZnO nanoneedles has been synthesized by thermal evaporation method. Both single and double tip ZnO nanoneedles were found coexistence in the as-synthesized products. The single tip nanoneedles are major products in the synthesis and a few double tip nanoneedles were also observed. The polarity of the nanoneedles was characterized by convergent beam electron diffraction (CBED) and the simulation results reveal that the polarity of the ZnO (0001) surface directs the preferential growth of the nanoneedles. It is also found that most of the double tip nanoneedles are originated from the joint growth of two single tip nanoneedles with a kink in the middle and smooth ones might be generated from forming thin layer of cubic structures in the double nanoneedle tips. A large quantity of ZnO nanorod building blocks without tips was also achieved by fast cooling. The formation of the nanoneedles and nanorods can be attributed to different cooling speeds in our experiments. The sharp single nanoneedle tip can be potentially used as scanning probe microscope or field-emission tips.
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