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Biomedical Materials


Graphene-reinforced calcium silicate coatings for load-bearing implants

Youtao Xie1, Hongqing Li1, Chi Zhang2, Xin Gu3, Xuebin Zheng1 and Liping Huang1

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Paper

Owing to the superior mechanical properties and low coefficient of thermal expansion, graphene has been widely used in the reinforcement of ceramics. In the present study, various ratios of graphene (0.5 wt%, 1.5 wt% and 4 wt%) were reinforced into calcium silicate (CS) coatings for load-bearing implant surface modification. Surface characteristics of the graphene/calcium silicate (GC) composite coatings were characterized by scanning electron microscopy. Results show that the graphene plates (less than 4 wt% in the coatings) were embedded in the CS matrix homogeneously. The surfaces of the coatings showed a hierarchical hybrid nano-/microstructure, which is believed to be beneficial to the behaviors of the cell and early bone fixation of the implants. Wear resistance measured by a pin-on-disc model exhibited an obvious enhancement with the adoption of graphene plates. The weight losses of the GC coatings decreased with the increase of graphene content. However, too high graphene content (4 wt% or more) made the composite coatings porous and the wear resistance decreased dramatically. The weight loss was only 1.3 ± 0.2 mg for the GC coating containing 1.5 wt% graphene (denoted as GC1.5) with a load of 10 N and sliding distance of 500 m, while that of the pure CS coating reached up to 28.6 ± 0.5 mg. In vitro cytocompatibility of the GC1.5 coating was evaluated using a human marrow stem cell (hMSC) culture system. The proliferation and alkaline phosphatase, osteopontin and osteocalcin (OC) osteogenesis-related gene expression of the cells on the GC1.5 coating did not deteriorate with the adoption of graphene. Conversely, even better adhesion of the hMSCs was observed on the GC1.5 coating than on the pure CS coating. All of the results indicate that the GC1.5 coating is a good candidate for load-bearing implants.


PACS

87.85.J- Biomaterials

87.19.R- Mechanical and electrical properties of tissues and organs

87.85.Lf Tissue engineering

87.64.Ee Electron microscopy

81.40.Pq Friction, lubrication, and wear

87.19.rs Movement

Subjects

Medical physics

Biological physics

Condensed matter: structural, mechanical & thermal

Dates

Issue 2 (April 2014)

Received 9 August 2013, revised 9 October 2013, accepted for publication 21 November 2013

Published 11 February 2014

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