Fiber Optic Humidity Sensor Based on Self-Assembled Polyelectrolyte Multilayers

Polyelectrolyte multilayers were self-assembled onto planar glass substrates and multimode optic fibers. The multilayer thin films deposited on glass substrates were characterized by using UV-vis spectroscopy and X-ray photoelectron spectroscope. The multilayer thin films containing hydrophilic side-groups possessed are affinity for uwer molecules. The adsorption and desorption of free water vapor gave rise to the changes in the refractive index and in the reflectance of the thin films. A multilayer thin film based fiber optic humidity sensor with an LED light source of 0.85 mum was designed. Under certain conditions, the rejected light intensity of the thin film sensor was a function of the humidity of air. About 30 bilayers was optimal for the multilayer thin film sensor working at wavelength of 0.85 mum. This sensor can work over almost the whole relative humidity range with very good sensitivity.

Substrate stiffness differentially impacts autophagy of endothelial cells and smooth muscle cells

Stiffening of blood vessels is one of the most important characteristics in the process of many cardiovascular pathologies such as atherosclerosis,angiosteosis,and vascular aging.Increased stiffness of the vascular extracellular matrix drives artery pathology and alters phenotypes of vascular cell.Understanding how substrate stiffness impacts vascular cell behaviors is of great importance to the biomaterial design in tissue engineering,regenerative medicine,and medical devices.Here we report that changing substrate stiffness has a significant impact on the autophagy of vascular endothelial cells(VECs)and smooth muscle cells(VSMCs).Interestingly,our findings demonstrate that,with the increase of substrate stiffness,the autophagy level of VECs and VSMCs showed differential changes:endothelial autophagy levels reduced,leading to the reductions in a range of gene expression associated with endothelial function;while,autophagy levels of VSMCs increased,showing a transition from contractile to the synthetic phenotype.We further demonstrate that,by inhibiting cell autophagy,the expressions of endothelial functional gene were further reduced and the expression of VSMC calponin increased,suggesting an important role of autophagy in response of the cells to the challenge of microenvironment stiffness changing.Although the underlying mechanism requires further study,this work highlights the relationship of substrate stiffness,autophagy,and vascular cell behaviors,and enlightening the design principles of surface stiffness of biomaterials in cardiovascular practical applications.

3D porous acellular cartilage matrix scaffold with surface mediated sustainable release of TGF-β3 for cartilage engineering

Acellular tissue matrix scaffolds are much closer to tissue’s complex natural structure and biological characteristics,thus assess great advantages in cartilage engineering.We used rabbit costal cartilage to prepare acellular microfilaments and further 3D porous acellular cartilage scaffold via crosslinking.Poly(_L-lysine)/hyaluronic acid(PLL/HA)multilayer film was then built up onto the surface of the resulting porous scaffold.Furthermore,TGF-β3 was loaded into the PLL/HA multilayer film coated scaffold to obtain a 3D porous acellular cartilage scaffold with sustained releasing of TGF-β3 up to 60 days.The success of this project will provide a new way for the treatment of articular cartilage defects.Meanwhile,the anchoring and on-site sustained releasing of growth factors mediated by polyelectrolyte multilayered film can also provide a new method for improving the biocompatibility and the biofunctionality for other implanted biomaterials.