RESUMO
This article presents a study of the influence of the substrate bias on the microstructure, preferred orientation, and mechanical and electrical properties of nanotwinned Cu film. The formation of a nanotwinned structure and (111) surface orientation can be properly controlled by applied substrate bias. High density nanotwinned structures were introduced into Cu films sputtered on SiC substrates with over 90% of (111)-orientation at - 150 V. Densely packed Cu nanotwins were observed within the columnar grains stacked up on each other along the film growth direction, with an average twin spacing of 19.4 nm. The Cu films deposited on SiC substrate via bias sputtering had surface roughness of 8.6 to 15.8 nm. The resistivity of the copper nanotwinned films sputtered with various substrate biases varied. The optimal indentation, 2.3 GPa, was found in the nanotwinned Cu film sputtered with a bias voltage of - 150 V. The effects of Ar ion bombardment on microstructure, surface morphology and properties are further discussed.
RESUMO
BACKGROUND: 17alpha-hydroxylase/17, 20-lyase encoded by CYP17 is the key enzyme in androgen biosynthesis pathway. Previous studies demonstrated the accentuation of the enzyme in patients with polycystic ovary syndrome (PCOS) was the most important mechanism of androgen excess. We chose CYP17 as the therapeutic target, trying to suppress the activity of 17alpha-hydroxylase/17, 20-lyase and inhibit androgen biosynthesis by silencing the expression of CYP17 in the rat ovary. METHODS: Three CYP17-targeting and one negative control oligonucleotides were designed and used in the present study. The silence efficiency of lentivirus shRNA was assessed by qRT-PCR, Western blotting and hormone assay. After subcapsular injection of lentivirus shRNA in rat ovary, the delivery efficiency was evaluated by GFP fluorescence and qPCR. Total RNA was extracted from rat ovary for CYP17 mRNA determination and rat serum was collected for hormone measurement. RESULTS: In total, three CYP17-targeting lentivirus shRNAs were synthesized. The results showed that all of them had a silencing effect on CYP17 mRNA and protein. Moreover, androstenedione secreted by rat theca interstitial cells (TIC) in the RNAi group declined significantly compared with that in the control group. Two weeks after rat ovarian subcapsular injection of chosen CYP17 shRNA, the GFP fluorescence of frozen ovarian sections could be seen clearly under fluorescence microscope. It also showed that the GFP DNA level increased significantly, and its relative expression level was 7.42 times higher than that in the control group. Simultaneously, shRNA treatment significantly decreased CYP17 mRNA and protein levels at 61% and 54%, respectively. Hormone assay showed that all the levels of androstenedione, 17-hydroxyprogesterone and testosterone declined to a certain degree, but progesterone levels declined significantly. CONCLUSION: The present study proves for the first time that ovarian androgen biosynthesis can be inhibited by silencing CYP17 expression. It may provide a novel strategy for therapy of hyperandrogenism diseases, and also set an example for the use of RNAi technology in endocrine diseases.
