Atomic layer deposition with rotary reactor for uniform hetero-junction photocatalyst, g-C3N4@TiO2 core-shell structures.

A heterojunction of TiO2 grown on g-C3N4 particles is demonstrated using atomic layer deposition (ALD), equipped with a specifically designed rotary reactor for maintaining stable mechanical dispersion of g-C3N4 particles during ALD. The photocatalytic activity of the g-C3N4@ALD-TiO2 core-shell composites was examined using the degradation of rhodamine B dye under visible light irradiation. The optimal composite with 5 ALD cycles of TiO2 exhibited the highest photocatalytic reaction rate constant among the composites with a range of ALD cycles from 2 to 200 cycles, which was observed to be 3 times higher than that of pristine g-C3N4 and 2 times higher than that of g-C3N4@TiO2 composite prepared using a simple impregnation method. The ALD-TiO2 were well-dispersed on the g-C3N4 surface, while TiO2 nanoparticles were agglomerated onto the g-C3N4 in the g-C3N4@TiO2 composite prepared by the impregnation method. This created uniform and stable heterojunctions between the g-C3N4 and TiO2, thus, enhancing the photocatalytic activity.

Pamidronate Down-regulates Tumor Necrosis Factor-alpha Induced Matrix Metalloproteinases Expression in Human Intervertebral Disc Cells.

BACKGROUND: N-containing bisphosphonates (BPs), such as pamidronate and risedronate, can inhibit osteoclastic function and reduce osteoclast number by inducing apoptotic cell death in osteoclasts. The aim of this study is to demonstrate the effect of pamidronate, second generation nitrogen-containing BPs and to elucidate matrix metallo-proteinases (MMPs) mRNA expression under serum starvation and/or tumor necrosis factor alpha (TNF-α) stimulation on metabolism of intervertebral disc (IVD) cells in vitro. METHODS: Firstly, to test the effect of pamidronate on IVD cells in vitro, various concentrations (10(-12), 10(-10), 10(-8), and 10(-6) M) of pamidronate were administered to IVD cells. Then DNA and proteoglycan synthesis were measured and messenger RNA (mRNA) expressions of type I collagen, type II collagen, and aggrecan were analyzed. Secondly, to elucidate the expression of MMPs mRNA in human IVD cells under the lower serum status, IVD cells were cultivated in full serum or 1% serum. Thirdly, to elucidate the expression of MMPs mRNA in IVD cells under the stimulation of 1% serum and TNF-α (10 ng/mL) In this study, IVD cells were cultivated in three dimensional alginate bead. RESULTS: Under the lower serum culture, IVD cells in alginate beads showed upregulation of MMP 2, 3, 9, 13 mRNA. The cells in lower serum and TNF-α also demonstrated upregulation of MMP-2, 3, 9, and 13 mRNA. The cells with various doses of pamidronate and lower serum and TNF-α were reveled partial down-regulation of MMPs. CONCLUSIONS: Pamidronate, N-containing second generation BPs, was safe in metabolism of IVD in vitro maintaining chondrogenic phenotype and matrix synthesis, and down-regulated TNF-α induced MMPs expression.