Surface engineering of titania nanotubes incorporated with double-layered extracellular vesicles to modulate inflammation and osteogenesis

Titania nanotubes(TNT)generated on titanium implant are emerged as important modification technique to facilitate bone regeneration.Mesenchymal stem cells(MSCs)-derived exosomes are membrane bound extracellular vesicles(EVs),which play an important role in tissue regeneration.The objective of this study was to generate an EVs hybrid TNT aiming at regulating inflammation,MSCs recruitment and osteogenesis.We isolated EVs from MSCs(MSCs EVs)and 3-day osteogenically differentiated MSCs(3d EVs).MSC EVs and 3d EVs exhibited round morphology under TEM,which also showed robust internalization by human bone marrow derived MSCs(hBMSCs).Next,we fabricated 3d EVs/MSC EVs hybrid TNT.When inflammatory macrophages were co-cultured with EVs hybrid TNT,the gene and protein expression of inflammatory cytokine were significantly reduced.Macrophage morphology was also examined by confocal laser scanning microscopy(CLSM)and scanning electron microscopy(SEM).Further migratory ability study using hBMSCs indicated significant enhancement of MSCs migration in EVs hybrid TNT.In addition,we further demonstrated significant increase of osteogenic differentiation of hBMSCs in EVs hybrid TNT.This study suggests that EVs hybrid TNT may serve as a viable therapeutic approach to enhance osteogenesis and bone regeneration.

Optical observations of LIGO source GW 170817 by the Antarctic Survey Telescopes at Dome A,Antarctica

The LIGO detection of gravitational waves(GW) from merging black holes in 2015 marked the beginning of a new era in observational astronomy. The detection of an electromagnetic signal from a GW source is the critical next step to explore in detail the physics involved. The Antarctic Survey Telescopes(AST3),located at Dome A, Antarctica, is uniquely situated for rapid response time-domain astronomy with its continuous night-time coverage during the austral winter. We report optical observations of the GW source(GW 170817) in the nearby galaxy NGC 4993 using AST3. The data show a rapidly fading transient at around 1 day after the GW trigger, with the i-band magnitude declining from 17:23 ± 0:13 magnitude to 17:72 ± 0:09 magnitude in ~1:8 h. The brightness and time evolution of the optical transient associated with GW 170817 are broadly consistent with the predictions of models involving merging binary neutron stars. We infer from our data that the merging process ejected about ~10^(-2) solar mass of radioactive material at a speed of up to 30% the speed of light.

The bright star survey telescope for the planetary transit survey in Antarctica

Transiting extrasolar planets(exoplanets),especially those orbiting bright stars, are desired for study of the diversity of planetary compositions, internal structures and atmospheres beyond our solar system. Dome A at Antarctica is a promising site for planetary transit surveys,where the continuous darkness and the large clear-sky fraction in the winter months greatly enhance the detection efficiency. The Chinese Small Telescope ARray and the Antarctic Survey Telescopes are the first facilities that have been operated at Dome A for use in exoplanet surveys. To increase the sky coverage, a low-temperature-resistant wide-field robotic telescope, named the bright star survey telescope(BSST), has been developed to join the ongoing planetary transit survey in Antarctica. The BSST has an aperture size of 300 mm and is equipped with a largeframe 4K×4K CCD camera to receive starlight from a 3.°4×3.°4 field of view. The BSST was operated at Lijiang observatory in April and May 2015 for a test run.Photometric precision of 3.5 mmag was achieved for stars with V～11 mag using 75 s exposures. The transiting events of two Jupiter-size exoplanets, HAT-P-3b and HATP-12 b, were observed on May 10 and May 20, 2015,respectively.