In the present study, two zinc(II) complexes containing bis-benzimidazole derivatives, Zn(bpbp)Cl₂ (1) and [Zn(bpbp)₂](ClO₄)₂·CH₃CH₂OH·H₂O (2) (bpbp = 2,6-bis(1-phenyl-1H-benzo[d]imidazol-2-yl)pyridine), have been designed, synthesized and evaluated for their in vitro anticancer activities. The underlying molecular mechanisms through which they caused the cancer cell death were also elucidated. The complexes were identified as potent antiproliferative agents against a panel of five human cancer cell lines by comparing with cisplatin. Complex 2 demonstrated dose-dependent growth inhibition on MCF-7 human breast carcinoma cells with IC₅₀ at 2.9 μM. Despite this potency, the complexes possessed great selectivity between human cancer cells and normal cells. Induction of apoptosis in MCF-7 cells by complex 2 was evidenced by accumulation of sub-G1 cell population, DNA fragmentation and nuclear condensation. Further investigation on intracellular mechanisms revealed that complex 2 was able to induce p53-dependent apoptosis in cancer cells by triggering DNA damage. On the basis of this evidence, we suggest that Zn(II) complexes containing bis-benzimidazole derivatives may be candidates for further evaluation as chemotherapeutic agents for human cancers.

Silicon nitride <mml:math display="inline"><mml:mrow><mml:mrow><mml:mo>(</mml:mo><mml:mrow><mml:msub><mml:mrow><mml:mtext>SiN</mml:mtext></mml:mrow><mml:mi>x</mml:mi></mml:msub></mml:mrow><mml:mo>)</mml:mo></mml:mrow></mml:mrow></mml:math>(SiNx) and parylene thin films were deposited onto flexible polyimide (PI) substrates using plasma-enhanced chemical vapor deposition and a parylene reactor for transparent barrier applications. The PI substrates from the Industry Technology Research Institute with high optical transmittance and high glass transition temperature were used. A relatively high growth temperature of <mml:math display="inline"><mml:mrow><mml:mn>200</mml:mn><mml:mo>°</mml:mo><mml:mi mathvariant="normal">C</mml:mi></mml:mrow></mml:math>200°C was chosen to deposit the <mml:math display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mtext>SiN</mml:mtext></mml:mrow><mml:mi>x</mml:mi></mml:msub></mml:mrow></mml:math>SiNx films. To characterize the <mml:math display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mtext>SiN</mml:mtext></mml:mrow><mml:mi>x</mml:mi></mml:msub></mml:mrow></mml:math>SiNx films deposited under different growth temperatures, a wet-etching process was performed to visualize the defect distribution in the barrier films. After 120 min of etching, the etching area ratio decreased from 44.9 to 6.7%, while the average defect spacing increased from 125 to <mml:math display="inline"><mml:mrow><mml:mn>450</mml:mn><mml:mspace width="0.5em"></mml:mspace><mml:mi>μ</mml:mi><mml:mi mathvariant="normal">m</mml:mi></mml:mrow></mml:math>450μm with increasing growth temperature. Under room temperature and relative humidity of 50%, four <mml:math display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mtext>SiN</mml:mtext></mml:mrow><mml:mi>x</mml:mi></mml:msub><mml:mo>/</mml:mo><mml:mtext>parylene</mml:mtext></mml:mrow></mml:math>SiNx/parylene stacks with the <mml:math display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mtext>SiN</mml:mtext></mml:mrow><mml:mi>x</mml:mi></mml:msub></mml:mrow></mml:math>SiNx films deposited at 80 and <mml:math display="inline"><mml:mrow><mml:mn>200</mml:mn><mml:mo>°</mml:mo><mml:mi mathvariant="normal">C</mml:mi></mml:mrow></mml:math>200°C were demonstrated to decrease the water vapor transmission rate to <mml:math display="inline"><mml:mrow><mml:mn>7.9</mml:mn><mml:mo>×</mml:mo><mml:msup><mml:mrow><mml:mn>10</mml:mn></mml:mrow><mml:mrow><mml:mo>−</mml:mo><mml:mn>4</mml:mn></mml:mrow></mml:msup></mml:mrow></mml:math>7.9×10−4 and <mml:math display="inline"><mml:mrow><mml:mn>7.41</mml:mn><mml:mo>×</mml:mo><mml:msup><mml:mrow><mml:mn>10</mml:mn></mml:mrow><mml:mrow><mml:mo>−</mml:mo><mml:mn>6</mml:mn></mml:mrow></mml:msup><mml:mspace width="0.5em"></mml:mspace><mml:mi mathvariant="normal">g</mml:mi><mml:mo>/</mml:mo><mml:msup><mml:mi mathvariant="normal">m</mml:mi><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msup><mml:mo>/</mml:mo><mml:mtext>day</mml:mtext></mml:mrow></mml:math>7.41×10−6g/m2/day , respectively. As a result, ultralow permeation can be achieved with less repeating barrier stacks by using high temperature deposited <mml:math display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mtext>SiN</mml:mtext></mml:mrow><mml:mi>x</mml:mi></mml:msub></mml:mrow></mml:math>SiNx films in the barrier structures.