Topical application of hyaluronic acid-RGD peptide-coated gelatin/epigallocatechin-3 gallate (EGCG) nanoparticles inhibits corneal neovascularization via inhibition of VEGF production

Neovascularization (NV) of the cornea disrupts vision which leads to blindness. Investigation of antiangiogenic, slow-release and biocompatible approaches for treating corneal NV is of great importance. We designed an eye drop formulation containing gelatin/epigallocatechin-3-gallate (EGCG) nanoparticles (NPs) for targeted therapy in corneal NV. Gelatin-EGCG self-assembled NPs with hyaluronic acid (HA) coating on its surface (named GEH) and hyaluronic acid conjugated with arginine-glycine-aspartic acid (RGD) (GEH-RGD) were synthesized. Human umbilical vein endothelial cells (HUVECs) were used to evaluate the antiangiogenic effect of GEH-RGD NPs in vitro. Moreover, a mouse model of chemical corneal cauterization was employed to evaluate the antiangiogenic effects of GEH-RGD NPs in vivo. GEH-RGD NP treatment significantly reduced endothelial cell tube formation and inhibited metalloproteinase (MMP)-2 and MMP-9 activity in HUVECs in vitro. Topical application of GEH-RGD NPs (once daily for a week) significantly attenuated the formation of pathological vessels in the mouse cornea after chemical cauterization. Reduction in both vascular endothelial growth factor (VEGF) and MMP-9 protein in the GEH-RGD NP-treated cauterized corneas was observed. These results confirm the molecular mechanism of the antiangiogenic effect of GEH-RGD NPs in suppressing pathological corneal NV

Tailoring the atomic structure of graphene nanoribbons by STM lithography

The practical realization of nano-scale electronics faces two major challenges: the precise engineering of the building blocks and their assembly into functional circuits. In spite of the exceptional electronic properties of carbon nanotubes only basic demonstration-devices have been realized by time-consuming processes. This is mainly due to the lack of selective growth and reliable assembly processes for nanotubes. However, graphene offers an attractive alternative. Here we report the patterning of graphene nanoribbons (GNRs) and bent junctions with nanometer precision, well-defined widths and predetermined crystallographic orientations allowing us to fully engineer their electronic structure using scanning tunneling microscope (STM) lithography. The atomic structure and electronic properties of the ribbons have been investigated by STM and tunneling spectroscopy measurements. Opening of confinement gaps up to 0.5 eV, allowing room temperature operation of GNR-based devices, is reported. This method avoids the difficulties of assembling nano-scale components and allows the realization of complete integrated circuits, operating as room temperature ballistic electronic devices.Comment: 8 pages text, 5 figures, Nature Nanotechnology, in pres

Patterning graphene nanostripes in substrate-supported functionalized graphene: A promising route to integrated, robust, and superior transistors

It is promising to apply quantum-mechanically confined graphene systems in field-effect transistors. High stability, superior performance, and large-scale integration are the main challenges facing the practical application of graphene transistors. Our understandings of the adatom-graphene interaction combined with recent progress in the nanofabrication technology indicate that very stable and high-quality graphene nanostripes could be integrated in substrate-supported functionalized (hydrogenated or fluorinated) graphene using electron-beam lithography. We also propose that parallelizing a couple of graphene nanostripes in a transistor should be preferred for practical application, which is also very useful for transistors based on graphene nanoribbon.Comment: Frontiers of Physics (2012) to be publishe

Turbulent primary breakup of round and plane liquid jets in still air

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/76929/1/AIAA-2002-1115-390.pd

Upregulated sirtuin 1 by miRNA-34a is required for smooth muscle cell differentiation from pluripotent stem cells

© 2015 Macmillan Publishers Limited. All rights reserved. microRNA-34a (miR-34a) and sirtuin 1 (SirT1) have been extensively studied in tumour biology and longevityaging, but little is known about their functional roles in smooth muscle cell (SMC) differentiation from pluripotent stem cells. Using well-established SMC differentiation models, we have demonstrated that miR-34a has an important role in SMC differentiation from murine and human embryonic stem cells. Surprisingly, deacetylase sirtuin 1 (SirT1), one of the top predicted targets, was positively regulated by miR-34a during SMC differentiation. Mechanistically, we demonstrated that miR-34a promoted differentiating stem cells' arrest at G0G1 phase and observed a significantly decreased incorporation of miR-34a and SirT1 RNA into Ago2-RISC complex upon SMC differentiation. Importantly, we have identified SirT1 as a transcriptional activator in the regulation of SMC gene programme. Finally, our data showed that SirT1 modulated the enrichment of H3K9 tri-methylation around the SMC gene-promoter regions. Taken together, our data reveal a specific regulatory pathway that miR-34a positively regulates its target gene SirT1 in a cellular context-dependent and sequence-specific manner and suggest a functional role for this pathway in SMC differentiation from stem cells in vitro and in vivo

Health Effects of Exposure to Natural Arsenic in Groundwater and Coal in China: An Overview of Occurrence

Between 2001 and 2005, 21,155 of 445,638 wells in 20,517 villages in 292 counties in 16 provinces from China, or 5% of wells, were found to contain > 50 μg/L arsenic (As) by field testing with the Merck As kit. We achieved quality assurance of analysis of at least 10% of the wells containing > 50 μg/L As using hydride generation atomic fluorescence spectrometry and silver dithiodicarbomate spectrometry. Our best estimate of the population exposed to > 50 μg/L As in drinking water was 582,769. This is probably an underestimate for China because of the limited area surveyed. In a survey of 135,492 individuals in eight provinces, we used the National Diagnosis Standard for Endemic Arsenicosis and identified 10,096 cases of arsenicosis with various degrees of skin lesions. The arsenicosis occurrence rate of 7.5% is likely an overestimate, because the survey focused more on known and suspected endemic areas of arsenicosis. The occurrence of arsenicosis correlates positively with the percentage of wells containing > 50 μg/L As, or at a ratio of 1 to 5%. Based on both the amount of As in well water and the rate of occurrence of arsenicosis, Shanxi province, Inner Mongolia autonomous region, and Jilin province are the top three areas in China as of 2005 for exposure to endemic As from drinking water. Our survey also identified exposure to high levels of As from wells in several provinces and from the indoor burning of coal containing high levels of As in Shaanxi province. These areas, however, have not had any reports of previous arsenicosis endemics. In the endemic areas, the average rate of occurrence of arsenicosis at advanced stages was 1.2%, possibly because of a long exposure time of > 20 years; the rate of occurrence increased to 2.7% when we included a high dose of As exposure from the indoor burning of coal. Mitigation to reduce As exposure remains a challenge in rural China