Stem cell therapies have been attracted much attention for the last few decades in the field of regenerative medicine and tissue engineering. 3-dimensional (3D) microenvironment surrounding the transplanted stem cells plays essential roles that influence the cell fate and behaviors. Thus advanced functional biomaterials and extracellular matrix (ECM) replacements with adjustable chemical, mechanical and bioactive properties are requisite in this field. In this study, PEG-based hyperbranched multifunctional homopolymers were developed via RAFT homopolymerization of the divinyl monomer of poly(ethylene glycol) diacrylate (PEGDA). Due to its high degree of multi-acrylate functionality, the hyperbranched polyPEGDA can rapidly crosslink with a thiolated hyaluronic acid at physiological condition and form an injectable hydrogel for cell delivery. In addition, by simply varying the synthesis recipe such as the reaction time and the ratio of the monomer to chain transfer agent (CTA), tunable polymer molecular weight, acrylate functionality degree and the cyclized/hyperbranched polymeric architecture can be finely controlled in one-step reaction. The gelation speed and the mechanical properties of this hydrogel can be easily adjusted by altering the crosslinking conditions. Rat adipose-derived stem cells (rASC) were embedded into the in situ crosslinked hydrogels, and their cellular behavior such as the morphology, viability, metabolic activity and proliferation were fully evaluated. The results suggested the hydrogel maintained good cell viability and be able to easily modify with other bioactive signals, which provide this injectable hydrogel delivery system a decent potential for polymeric biomaterial and tissue regeneration applications.

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In this paper, an organic/inorganic molybdenum series Cr-free coating was formed on galvanized steel by simple immersion and its corrosion behavior was compared to that of a typical chromate coating. Molybdate and 1-Hydroxy-ethylidene-1, 1-diphosphonic acid (HEDP) were used as corrosion inhibitor, as well as acrylic resin and silane were used as film-former and coupling agents, respectively. The corrosion behavior of the coatings was evaluated by Neutral salt spray (NSS), Electrochemical impedance spectroscopy (EIS) and Tafel polarization. The surface topography of the samples was observed by Scanning Electron Microscopy (SEM). The results indicated that the corroded area of the Mo-HEDP treatment was only corroded 2% after 72 h spraying, while the corrosion behaviour of Mo-HEDP was closed to that of Cr pretreatment due to the synergistic reaction of molybdate and HEDP. Compared with the film of Cr treatment, Mo-HEDP passivating coating was more environmentally friendly.

Al2O3ceramic coating was successfully prepared on GH132 super alloy by cathodic plasma electrolytic oxidation in (NO3)3·9H2O electrolyte. The structure and chemical composition of the coatings were characterized. The results showed that the as prepared coating was composed of Al2O3crystal, including much α-Al2O3andsomeγ-Al2O3two types of Al2O3.A few Fe elements entered into in the substrate and nearly no other elements were found in the coating surface. The Al2O3.coating showed coarse surface and there were some small pits on the surface. The diameters of pits were not more than 20 um. The thickness of coating was about 50μm.

TiO2 composite photocatalytic film was prepared on steel by plasma electrolytic oxidation in aluminate electrolyte. The microstructure of the composite film was investigated by XRD and SEM. The photocatalytic properties of the films treated with different time were studied by photocatalytic degradation of Rhodamine B with various irradiation time. The results revealed that the as prepared film was composed of crystal phase of much A-TiO2 and a little γ-Al2O3. The film surface was rough and porous. The pores are in the dimensions of 2-8 μm. The photocatalytic experimental results showed that for the same irradiation time, the removal ratio of Rhodamine B of the films gradually increased with increasing the treating time. For each film, the removal ratio of Rhodamine B of the film also gradually increased when increase the irradiation time. The 30 min treated sample exhibited a removal ratio of 80% in 2h irradiation of ultraviolet light.