RESUMO
The objective of this study was to evaluate the biocompatibility of trimethylsilane (TMS) plasma nanocoatings modified with NH3/O2 (2:1 molar ratio) plasma post-treatment onto cobalt chromium (CoCr) L605 alloy coupons and stents for cardiovascular stent applications. Biocompatibility of plasma nanocoatings was evaluated by coating adhesion, corrosion behavior, ion releasing, cytotoxicity, and cell proliferation. Surface chemistry and wettability were studied to understand effects of surface properties on biocompatibility. Results show that NH3/O2 post-treated TMS plasma nanocoatings are hydrophilic with water contact angle of 48.5° and have a typical surface composition of O (39.39 at.%), Si (31.92 at.%), C (24.12 at.%), and N (2.77 at.%). The plasma nanocoatings were conformal to substrate surface topography and had excellent adhesion to the alloy substrates, as assessed by tape test (ASTM D3359), and showed no cracking or peeling off L605 stent surfaces after dilation. The plasma nanocoatings also improve the corrosion resistance of CoCr L605 alloy by increasing corrosion potential and decreasing corrosion rates with no pitting corrosion and no mineral adsorption layer. Ion releasing test revealed that Co, Cr, and Ni ion concentrations were reduced by 64-79%, 67-69%, and 57-72%, respectively, in the plasma-nanocoated L605 samples as compared to uncoated L605 control samples. The plasma nanocoatings showed no sign of cytotoxicity from the test results according to ISO 10993-05 and 10993-12. Seven-day cell culture demonstrated that, in comparison with the uncoated L605 control surfaces, the plasma nanocoating surfaces showed 62 ± 7.3% decrease in porcine coronary artery smooth muscle cells (PCASMCs) density and had comparable density of porcine coronary artery endothelial cells (PCAECs). These results suggest that TMS plasma nanocoatings with NH3/O2 plasma post-treatment possess the desired biocompatibility for stent applications and support the hypothesis that nanocoated stents could be very effective for in-stent restenosis prevention.
RESUMO
The effects of oleanolic acid (OA) on the fertility of male mice were investigated using both invivo and invitro experimental models. The experimental group (n=12) was treated with a daily dose of 30mgOAkg-1 bodyweight (i.p.), while the control group (n=6) received a daily dose of 10% ethanol solution (1mLkg-1 bodyweight). The effect of OA on the permeability status of TM4 Sertoli monolayers was investigated by measuring the transepithelial electrical resistance (TER), intracellular electrical resistance and semiquantitative RT-PCR. After 45 days, OA-treated males produced no pregnancies but in the control group, all 12 females were impregnated (69 offspring). Male mice, which demonstrated sterility when exposed to OA, recovered their fertility after 30 days (78 offspring). Testicular histological observations of OA-treated mice showed detachment of adjacent Sertoli-Sertoli cells. A control monolayer developed TER of 300-400 Ω.cm2, but OA (50, 100, 200µgL-1) treated monolayers developed TER of approximately 100Ω.cm2. Intracellular electrophysiological and RT-PCR data supported the premise that OA compromised tight junctional permeability. The study demonstrated reversible contraception in male mice by increasing the permeability of the germinal epithelium and further postulates that contraceptive reversibility is brought about by the reconstitution of the paracellular junctions between adjacent Sertoli cells.
