Hanqing Gu

In vitro comparison of the hemocompatibility of diamond-like carbon and carbon nitride coatings with different atomic percentages of N.

Carbon nitride (CNx) and diamond-like carbon (DLC) coatings were prepared by dc magnetron sputtering at room temperature. Different partial pressures of N2 were used to synthesize CNx to evaluate the relationship between the atomic percentage of nitrogen and hemocompatibility. Auger electron spectroscopy and atomic force microscopy indicated atomic percentages of N of 0.12 and 0.22 and that the CNx coatings were smooth. An in vitro study of the hemocompatibility of the coatings revealed that both CNx coatings had better anticoagulant properties and lower platelet adhesion than DLC. Compared with CN0.12, the CN0.22 coating showed longer dynamic clotting time (about 42 min), static clotting time (23.6 min) and recalcification time (45.6 s), as well as lower platelet adhesion (102 cells μm−2), aggregation, and activation. The presence of nitrogen in the CNx coatings induced their enhanced hemocompatibility compared with DLC.

Shape-Control of Three-Dimensional Self-Assembly Graphene by Hydrothermal Reaction Time and Its Biological Application

In this paper, three-dimensional self-assembly graphene (3D-G) was prepared by the hydrothermal synthesis method, and 3D-G was designed as a suitable biological scaffold for cell growth and adhesion. The shape of 3D-G was tuned by adjusting the hydrothermal reaction time (6 h, 12 h, 18 h and 24 h). Then the scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS) analyses were used to characterize the microstructure and component of 3D-G, which showed that the length, diameter, pore size and defects of 3D-G were all decreased as the reaction-time increased. In vitro cell culture experiment, the cytocompatibility of 3D-G prepared under different hydrothermal reaction time was assessed using mouse fibroblast cells (L929) via 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT). Meanwhile, the cell adhesion, growth and proliferation were also observed by SEM. These results showed that the 3D-G with the reaction time of 24 h (3D-G/24 h) had the best cytocompatibility, which could be used as tissue scaffolds for cell growth.

Enhanced cell growth on 3D graphene scaffolds implanted with nitrogen ions

One of the key challenges in engineering tissues for cell-based therapies is developing biocompatible scaffold materials to direct cell behavior. In this paper, the cytocompatibilities of a flexible three-dimensional graphene scaffold (3D-G) and the same scaffold implanted with nitrogen ions (N+/3D-G) are compared using an in vitro assay based on 3(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide. The N+/3D-G samples were prepared from low-temperature hydrothermally synthesized flexible 3D-G by ion implantation and were found to display improved adhesion and proliferation of rat osteoblast and mouse fibroblast cells. In particular, the N+/3D-G sample with a nitrogen content of ∼10% showed the highest levels of cell viability and proliferation. The flexible N+/3D-G has potential applications as a biocompatible scaffold material that provides improved surface area and hydrophilic groups for cell growth and proliferation.

Influence of Sputtering Power on the Structure and Mechanical Properties of Zr-Nb-N Nanocomposite Coatings Prepared by Multi-Target Magnetron Co-Sputtering

Ternary Zr-Nb-N nanocomposite coatings were synthesized on Si(100) substrates by Multi-target Magnetron Co-sputtering. The structure and chemical composition and binding energy of coatings were characterized by X-ray diffractometry (XRD) and Energy-dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS). The results of measurements of Nano Indenter indicated that the maximum hardness was up to 36 GPa and elastic modulus was close to 425 GPa at the 30 W of Zr power and 120 W of NbN power. The hardest coating also showed the modest residual stress. These Zr-Nb-N coatings appeared to be a promising composite coating system suitable for engineering applications.