Enhanced spreading, migration and osteodifferentiation of HBMSCs on macroporous CS-Ta - A biocompatible macroporous coating for hard tissue repair.

Macroporous tantalum (Ta) coating was produced on titanium alloy implant for bone repair by cold spray (CS) technology, which is a promising technology for oxygen sensitive materials. The surface characteristics as well as in vitro cytocompatibility were systematically evaluated. The results showed that a rough and macroporous CS-Ta coating was formed on the Ti6Al4V (TC4) alloy surfaces. The surface roughness showed a significant enhancement from 17.06 µm (CS-Ta-S), 27.48 µm (CS-Ta-M) to 39.21 µm (CS-Ta-L) with the increase of the average pore diameter of CS-Ta coatings from 138.25 µm, 198.25 µm to 355.56 µm. In vitro results showed that macroporous CS-Ta structure with tantalum pentoxide (Ta2O5) was more favorable to induce human bone marrow derived mesenchymal stem cells (HBMSCs) spreading, migration and osteodifferentiation than TC4. Compared with the micro-scaled structure outside the macropores, the surface micro-nano structure inside the macropores was more favorable to promote osteodifferentiation with enhanced alkaline phosphatase (ALP) activity and extracellular matrix (ECM) mineralization. In particular, CS-Ta-L with the largest pore size showed significantly enhanced integrin-α5 expression, cell migration, ALP activity, ECM mineralization as well as osteogenic-related genes including ALP, osteopontin (OPN) and osteocalcin (OCN) expression. Our results indicated that macroporous Ta coatings by CS, especially CS-Ta-L, may be promising for hard tissue repairs.

Study on P, N, and Mo Tri-Doped TiO2--Preparation and Photocatalytic Activities Under Visible Light.

Phosphorous (P), nitrogen (N), and molybdenum (Mo) tri-doped titanium dioxide ((P, N, Mo)-TiO2) were fabricated by hydrothermal method with titanyl sulfate (TiOSO4) and ammonium phosphomolybdate ((NH4)3H4[P4(Mo207)6]) as precursors. (P, N, Mo)-TiO2 was characterized by XRD, Raman, XPS and other advanced analysis devices. And the photocatalytic activites of (P, N, Mo)-TiO2 were evaluated using methylene blue (MB) and sulfosalicylic acid (SSA). Improved visible light response and photocatalytic properties were observed. The mechanism of photodegradation of MB and SSA under visible light by (P, N, Mo)-TiO2 was also proposed.

Study on (P, N, Mo)-TiO2 Photocatalytic Coating and Its Photocatalytic Activities Under Visible Light.

Phosphorous (P), nitrogen (N) and molybdenum (Mo) ternary co-doped titania (TiO2) photocatalytic coatings were fabricated by Cold Gas Dynamic Spraying (CGDS) with (P, N, Mo)-TiO2 nano powders as feedshock. (P, N, Mo)-TiO2 nano powders and cold sprayed (P, N, Mo)-TiO2 coatings were characterized by SEM, Raman, XRD, XPS and UV-Vis spectra. Experiment results show that the characteristics of (P, N, Mo)-TiO2 nano powders can be remained in the coatings as more as possible by CGDS. Cold sprayed (P, N, Mo)-TiO2 coatings exhibited good photocatalytic activity under visible light. In addition, the mechanism of (P, N, Mo)-TiO2 photocatalysts was also proposed.

Effect of hot water and heat treatment on the apatite-forming ability of titania films formed on titanium metal via anodic oxidation in acetic acid solutions.

Titanium and its alloys have been widely used for orthopedic implants because of their good biocompatibility. We have previously shown that the crystalline titania layers formed on the surface of titanium metal via anodic oxidation can induce apatite formation in simulated body fluid, whereas amorphous titania layers do not possess apatite-forming ability. In this study, hot water and heat treatments were applied to transform the titania layers from an amorphous structure into a crystalline structure after titanium metal had been anodized in acetic acid solution. The apatite-forming ability of titania layers subjected to the above treatments in simulated body fluid was investigated. The XRD and SEM results indicated hot water and/or heat treatment could greatly transform the crystal structure of titania layers from an amorphous structure into anatase, or a mixture of anatase and rutile. The abundance of Ti-OH groups formed by hot water treatment could contribute to apatite formation on the surface of titanium metals, and subsequent heat treatment would enhance the bond strength between the apatite layers and the titanium substrates. Thus, bioactive titanium metals could be prepared via anodic oxidation and subsequent hot water and heat treatment that would be suitable for applications under load-bearing conditions.