Scaffold biomaterials with open pores and channels are favourable for cell growth and tissue regeneration, however the inherent poor mechanical strength and low surface activity limit their applications as load-bearing bone grafts with satisfactory osseointegration. In this study, macroporous graphene oxide (GO) modified titanate nanowire scaffolds with desirable surface chemistry and tunable mechanical properties were prepared through a simple hydrothermal process followed by electrochemical deposition of GO nanosheets. The interconnected and porous structure of the GO/titanate nanowire scaffolds provides a large surface area for cellular attachment and migration and displays a high compressive strength of approximately 81.1 MPa and a tunable Young's modulus over the range of 12.4-41.0 GPa, which satisfies site-specific requirements for implantation. Surface chemistry of the scaffolds was modulated by the introduction of GO, which endows the scaffolds flexibility in attaching and patterning bioactive groups (such as -OH, -COOH and -NH 2 ). In vitro cell culture tests suggest that the GO/titanate nanowire scaffolds act as a promising biomaterial candidate, in particular the one terminated with -OH groups, which demonstrates improved cell viability, and proliferation, differentiation and osteogenic activities.Considering the ageing population, and the giant number of osteoporosis and traffic accident victims, it is a pressing need to design, develop and commercialize synthetic materials for bone repair and replacement, in particular at heavy load bearing sites, such as hip and joints 1-2 . The gold criteria in terms of design of manmade biomaterial grafts, emphasize the compatibility with a high degree to those of natural bone tissues, including structure, morphology, topography, chemistry, mechanical properties and biological functionalities [3][4][5] . Of all existing and being developed biomaterials, scaffolds are the most favourable components for tissue regeneration and replacement, owing to their intriguing structural characteristics, which elicit resemble mechanical performances and functionalities to those of the human bones for satisfactory host-implant interactions, osteoconductivity, and integration [6][7] . The porous structure of tissue-engineering scaffolds provides cells with essential space as residence, facilitates exchange of nutrients with metabolic wastes between internal and external environments efficiently 8 , and promotes tissue ingrowth and regeneration [9][10] . Meanwhile, adequate mechanical strength is essential to establish a favourable stress environment for the growth of neo-tissues 11 , providing sustainable supports, resisting cell contractile forces and minimizing wear and shrinkage, both in vitro and in vivo 12 . Matching the mechanical properties well to the site-specific requirements of scaffolds will promote engineering techniques for high yields of robust tissues 13 . The high porosity (up to 95%) of the synthetic scaffolds gives rise to both enhanced cellular activities and...
